This file has been designed to help you to
find information about Laponite® products quickly and easily. Click on the
links or questions in the tables below to allow you to move around the page. For
any technical support requirement, or if you cannot find what you are looking
for on this page, please e-mail our Technical team at: firstname.lastname@example.org
Select from the following categories
General & Miscellaneous
When the word, “synergy” is
used in relation to an interaction between Laponite® and another raw
material, what does this word mean?
In which decade were
Laponite® products first sold commercially?
Are there technical
literature or information resources available on Laponite® in languages other
Is there an organo- version of
difference between RD/ XLG and RDS/XLS?
What is the usual delivery
form of Laponite® products?
Where is Laponite® made?
Where can I find information on
rheological additives are available from Rockwood?
What is “Liquid Laponite®”?
Where can I order Laponite®
samples or get formulation or handling recommendations?
Does high shear damage
Do I need to use high shear to
Do I have to wait for Laponite® RD
to gel before I add it to my formula?
What is the shelf life of
Can you give guidelines on the
best way to disperse Laponite?
Using Laponite® in
|Why have I got gel seeds in my
paint containing Laponite®?
Can I thicken alcohols or
glycols, or other polyols using Laponite®?
compatible with cationic surfactants?
I have a list of…e. g…5 to 10
chemicals…in a formula, will Laponite® work/ how can I make Laponite® work in
I’ve got hard water and
want to make clear gels of Laponite® in water. Is there an additive that I
can use to treat my water source?
Can I use Laponite® to make skincare
formulas at natural skin pH?
Why can’t I add Laponite®
powder directly to my formula?
Can I thicken acidic
products using Laponite®?
Do I need to neutralise
Laponite® to make it gel?
After I have made my formula,
I see a gradual reduction in viscosity. Why?
After I have made my formula,
I see a gradual increase in viscosity. Why?
Which CMC type gives best
synergy with Laponite®?
Can I use Laponite® to make
conductive/ antistatic paints?
What is the best pH range for
What level/type of
surfactants can be used with Laponite®?
& Rheological Properties
What is the specific density
What phrase best describes
the rheology of a Laponite® gel?
What is the cation exchange
capacity (CEC) of Laponite®?
If I prepare a dispersion of
Laponite® JS at 20% solids content, what would it look like after 1 day?
What is the benefit of using
Laponite® as thickener in my formulation over gums or polymers?
What is the highest level of
conductivity/resistivity that you can expect to obtain when making an
antistatic coating on paper using Laponite®?
What is the refractive index
What are the typical
dimensions of a single crystal of Laponite®?
What chemical is used to
convert a gel forming grade, e.g. Laponite® B to a sol forming grade, e.g.
What’s a sol grade?
What is the difference between a temporary
sol and a permanent sol?
In tap water, Laponite® RD
can form a strong gel at 2% concentration, but in deionised water, it is a
low viscosity liquid. What’s the explanation for this?
Status / Health & Safety
In what year were Laponite®
products last tested on animals?
What are the CAS/ Einecs
numbers/ INCI names for Laponite® products?
What is the German Water
Hazard Classification for Laponite®?
Has Laponite® ever been
tested on animals?
What would happen if I ate
What is the INCI name for
What toxicology and
regulatory information is available for Laponite® products?
1. Do I need to use high shear to disperse Laponite®?
High shear mixing is not required to disperse
Laponite®; however, high shear mixing will not damage Laponite®, as is the case
for some polymeric thickeners. A high-speed mixer is often recommended,
especially when making high solids concentration dispersions of Laponite® sol
2. Does high shear damage Laponite®? No. High shear mixing will not damage Laponite®, as is
the case for some polymeric thickeners
3. Do I need to neutralise Laponite® to make it gel? No. Laponite® will disperse into water with stirring.
Gel formation occurs as a result of interactions between the Laponite® and the
components in a formulation.
4. Has Laponite® ever been tested on animals? At the time of writing, in 2006, the last time that
Laponite® products were tested on animals was over 23 years ago. Laponite®
products were tested on animals several times during the period between 1969
and March 1983. It is Rockwood’s firm intention not to carry out animal testing
on Laponite® in the future, but to use in vitro and human testing procedures.
5. What would happen if I ate some Laponite®? Our first and strong recommendation would be to seek
professional medical advice immediately. Rinse the mouth thoroughly and drink
plenty of water. Show your medical officer technical literature relating to
Laponite® products. Safety Data Sheets can be downloaded from www.laponite.com. From the home page, click on the Technical Information button, select MSDS from
the list that opens and then click on the Laponite® grade.
Laponite® products are classed as Low Acute Toxicity
(LD50 oral rat > 8g/ kg body weight), but may cause gastric irritation.
6. What chemicals are used to convert a gel forming grade, e.g.
Laponite® B to a sol forming grade, e.g. Laponite® JS? Tetra-sodium pyrophosphate- trade name, tetron and often referred to as
TSPP, is the dispersant added to Laponite® in order to produce “temporary sol
grades”. This salt is milled to approximately the same particle size as the
Laponite® powder in order to improve physical stability of the blended powders
on storage. The large negatively charged pyrophosphate anion that is produced
when TSPP dissolves, acts to neutralise the positive charges on the edge of the
Laponite® crystal. This mechanism prevents the Laponite® sol grade from forming
a gel in water only.
The additive used in “permanent sol grades”
Laponite® S482 and Laponite® SL25 is a proprietary substance. For an
explanation of the differences between temporary and permanent sol grades,
a sol grade?
7. In tap water, Laponite® RD can form a strong gel at 2%
concentration, but in deionised water, it is a low viscosity liquid. What’s the
explanation for this?
gels, or builds viscosity in dispersion in water, by a mechanism of
interactions between the Laponite® nano-particles, water molecules and ions, or
other electrolytes in solution in the water. Put simply, it is necessary to
have some electrolyte present in a dispersion of Laponite® in water, in order
for it to gel efficiently. Most tap water sources contain enough dissolved
solids to allow gel formation to occur, but with a conductivity close to zero,
deionised water does not contain enough electrolyte or dissolved solids to
cause efficient gel formation. This effect is shown schematically in the graph
Effect of electrolyte concentration upon Gel Strength of
Laponite® at 2% concentration in water
Following on from
this, Laponite® can be used efficiently in formulated products that are based
upon deionised water, as the other components of the formulation will
automatically provide the electrolytes that trigger gel formation. In practical
terms, a clear gel of Laponite® RD in water of low electrolyte content can be
useful as a simple model for demonstrating the unique properties that can be
imparted when using the product as rheological additive in water based
The effects of
electrolyte upon Laponite® are described in detail on pages 18 to 20 of the
Laponite® Technical Brochure, “Laponite® performance additives”. This can be
downloaded as a pdf file from the following web link: http://www.laponite.com/pdfs/laponite.pdf
It should be noted that some hard tap water sources
may contain too much dissolved solids to allow gel formation to occur. This can
be overcome by use of a sol grade, e.g. Laponite® RDS, or by using Laponite® RD
in combination with a sequestering agent (a water-softener) as detailed in [Click here] I’ve got hard water and want to make clear gels of Laponite®
in water. Is there an additive that I can use to treat my water source?
8. Can I thicken alcohols or glycols, or other polyols using Laponite®?
It’s possible to thicken up to 40% solutions in water
of these chemicals with Laponite®. Many formulations, such as speciality
surface coatings, where Laponite® is commonly used contain up to 10% of glycol.
It is important that Laponite® is pre-dispersed in water, before a high
concentration of glycol or alcohol is added. However, at lower glycol addition
levels, say <5% in water, Laponite® powder will disperse into this more
dilute solution. Glycols have an important role in helping Laponite® be more
easily used in low free water (water-lean) formulations. If glycol is added
with Laponite® RD at a ratio of 1:1 in pre-mixes in water at 3% to 4% Laponite®
content, the glycol has a temporary dispersant effect on the Laponite®. This
allows the pre-mix to produced at lower viscosity and so can make it much
easier to combine with other formulation ingredients such as dispersion resins.
9. What are the advantages of using Laponite® as thickener in my
formulation compared with using gums or polymers? Laponite® develops an individual rheological property
in a formulation- it is highly thixotropic and shear thinning. Laponite® gives
very high, gel-like viscosity at low shear rates; this structure can break down
under shear to give very low viscosity that will allow a formulation to flow
easily. After shear is removed, the viscosity of the formulation will recover.
In many cases this can lead to better performance, e.g. for spraying, pumping
etc. It can also be valuable as a way of developing light, non-stick texture to
personal care products or surface coating. In other types of formulation, a gum
or polymer may give better or more cost-effective performance.
In many types of formulas, Laponite® is actually used
in combination with thickeners, such as gums or polymers. This can have
significant benefits, such as a synergistic increase in viscosity build or an
increase in tolerance to higher levels of surfactants or salts. It is also a
useful technique for…”rheological engineering”…i.e. taking different aspects
from the rheology of two or more thickeners to design a precise rheological
profile for a certain application.
10. I have a list of…e. g…5 to 10 chemicals…in a
formula, will Laponite® work/ how can I make Laponite® work in the formula?
In fact, this is
the most frequently asked question about Laponite®- but as every formulation chemist
working with Laponite® has a different set of 5 to 10 chemicals that they are
working with then it’s also the most difficult question to give a specific
answer to. General
guidelines, in the form of a trouble-shooting checklist (Page 8 of the
Laponite® Technical Brochure), are given in the table below. For additional
help with using Laponite® in your own formulation, you are requested to contact
by e-mail: email@example.com
trouble shooting checklist and how to achieve optimum
• Order of addition
Adding Laponite® powder directly to a finished
product, latex or electrolyte solution will result in flocculation or low
viscosity build. Laponite® products should always be premixed in water before
• Preparation of Laponite® premix
Laponite® powder should be added to water at room
temperature with rapid agitation. Slow agitation and short mixing times will
produce partially hydrated Laponite® particles, which may sink to the bottom
of the mixing vessel and produce a viscous gel coating that is difficult to
• The rate of hydration of Laponite® is temperature
• If water temperature is low, 10ºC or less, then
hydration time will be increased.
• If Laponite® powder is added to hot water, 35ºC or greater,
then the rate of hydration is so rapid that gel coated clumps of powder can
• After the powder has wetted out, the temperature of
the premix may be raised to increase the rate of hydration.
• Water quality
Calcium and magnesium ions present in very hard water
can reduce the rate of hydration in gel forming grades of Laponite®, leading
to reduced efficiency in viscosity build. This can readily be overcome by the
addition of a suitable sequestering agent such as EDTA or a sodium
polyphosphate salt – or by using the appropriate sol-forming grade.
• Formulation pH
Laponite® is most useful in the range pH6 to pH13.
However, when correctly stabilised, Laponite® can provide effective
anti-settling and thixotropic properties in neutral through to highly acidic
• Recommended agents for pH adjustment include:
To lower formulation pH:
• sodium citrate/citric acid buffer
To increase formulation pH:
• ammonia solution, sodium hydroxide, potassium
hydroxide, sodium silicate, AMP95, DMAMP80.
In certain cases tertiary amines such as TEA or DMEA
may be used to neutralise acidic resins, however,
neutralisation should always be completed before
addition of a Laponite® premix into the formulation.
• Compatibility with other components
Laponite® has one of the most extensive application
ranges of all water based rheological additives – clear evidence of its compatibility across a wide
spectrum of formulation additives. Laponite® products are anionic, and their
use in formulations containing cationic compounds is not recommended.
11. I’ve got hard water and want to make clear gels
of Laponite® in water. Is there an additive that I can use to treat my water
terms, the most appropriate way to deal with issues arising from use of
Laponite® products with hard water is to choose one of the sol forming grades,
e.g. Laponite® RDS, S482 or SL25 . However, a clear gel of Laponite® in water
can be useful for technical purposes as a simple model for demonstrating the
unique properties that can be imparted by using Laponite® as rheological
additive in water based formulated products.
proven additive for hard water as far as Laponite® and clear gels is concerned
is tetra-sodium pyrophosphate, the additive that is used to convert Laponite®
into sol forming grades. TSPP will produce insoluble Ca & Mg salts with
colloidal particle-size…i.e. the insoluble particles are very small and do not
cause haziness. The problem with TSPP is that it is also a dispersant for
Laponite® RD and if added in excess it may cause sol formation or reduction in
gel strength. Because of this, it is essential to just add the right amount of
polyphosphate to get rid of most of the hardness, but avoid having too much so
that gel strength is affected.
deal with the problem…is it possible to get a typical water analysis? Your
water supply company can sometimes give this. If we know the level of water
hardness, then we can make a calculation to estimate the amount of softening
salt to add in order to remove the Ca & Mg that is causing Laponite® to be
hazy. With this information, we do a calculation to suggest the required
softener addition level using the same chemical equation that we use to show
how Laponite® sol grades can be activated…
+ 2CaCO3= Ca2P2O7 (s) + 2Na2CO3
complicating factor in this is that water hardness is often expressed in
different ways in different regions; use the table below to estimate the TSPP
addition level that will be required for your own water source.
If water hardness is expressed as…
…multiply the water hardness figure by
the factor below to estimate the TSPP addition level (in ppm) required to
sequester all hardness in the water…
1 German Degree of hardness
1 English (Clarke) Degree of hardness
1 French Degree of hardness
12. Are there technical literature or information
resources available on Laponite® in languages other than English? The Laponite® Technical Brochure, “Laponite- performance
additives” is also available in French, German and Japanese. French and German
versions of this brochure are reproduced on the Laponite® Technical CD-ROM. A
further information resource is our worldwide network of distributors. The
contact details of your local or regional distributor for Laponite® products
can be found on the following web link… http://www.scprod.com/distributor_contact.asp
13. In which decade were Laponite® products first
sold commercially? 1960’s
14. In what year were Laponite® products last tested
on animals? 1983
15. What phrase best describes the rheology of a
Laponite® gel? Highly shear thinning and thixotropic.
16. Why can’t I add Laponite® powder directly to my
formula? In order to develop any functional properties, e.g.
rheology or surface conductivising, etc., Laponite® must be converted from the
highly agglomerated form in which it is supplied into a fully dispersed state
of separated, individual crystals. A typical grain of powder of the product as
supplied, contains in the region of 1013 individual nano-crystals of
Laponite®. In order for these nano-crystals to separate from each other,
Laponite® must undergo a chemical interaction with water- this process is
described in detail on pages 18-19 of the Laponite® Technical Brochure,
“Laponite® the performance enhancer”. If other chemicals are present when
Laponite® is dispersed, these chemicals can interfere with the dispersion
process and slow it down, or even halt it completely. The result of this would
be to reduce, or prevent the development of the desired functional properties.
We consistently recommend that Laponite® products should always be premixed in water before use.
17. Is there an organo- version of Laponite®? It is possible to make organo-modified versions of
Laponite® products; these are mainly used for research and development
purposes. Commercial organo-Laponite® products are not manufactured at the
18. What are the CAS/ Einecs numbers/ INCI names for
A summary of the
regulatory status of Laponite® products is given in the table below.
RD, XLG, D, DF
RDS, XLS, DS
silicic acid, lithium magnesium sodium
Hydrous sodium lithium magnesium silicate
Hydrous sodium lithium magnesium
INCI and CTFA name
Sodium magnesium silicate
Sodium magnesium silicate (and) tetra
Sodium magnesium fluorosilicate (and)
tetra sodium pyrophosphate
Canadian DSL no.
1-486, magnesium silicate
Drug Master File
Type 1 No. 9910
ASTM (Non-toxic Status for Arts and
California Proposition 65
Laponite® products do not contain
Laponite® products contain: lead < 3
mg/kg; mercury < 2 mg/kg;
arsenic < 1 mg/kg; nickel < 2 mg/kg;
lithium < 0.4 wt.%
19. What is the German Water Hazard Classification
for Laponite®? The German Water Hazard Classification is WGK 1- for
all Laponite® grades.
20. What is the INCI name for Laponite® XL21? The INCI name for XL21 is sodium magnesium
21. Can I use Laponite® to make skincare formulas at
natural skin pH? Yes, it is possible to make skin care formulas
containing Laponite® in the pH range 5 to 6. Rockwood has developed Laponite®
products and starting formulations that allow the preparation of a wide range
of different types of leave-on and rinse-off skin care products, such as facial
moisturisers, anti-ageing creams, hand and body lotions, sun care, baby care,
skin and hair wash etc. For more information, send an e-mail to firstname.lastname@example.org and ask for Laponite® Technical Bulletin L465,
“New developments with Laponite® in Personal care”. This bulletin can also be
downloaded at the following web link: http://www.laponite.com/application_bulletins.asp
22. Why have I got gel seeds in my paint containing
Laponite®? This problem could
have been caused by one of several reasons. If the suggestions below do not resolve the
problem, please contact us on email@example.com for assistance.
…and how to avoid
was added as a powder without pre-mixing in water
guidance is to ensure that Laponite® is always pre-dispersed in water before
other ingredients are added
pre-gel of Laponite® was combined with a low viscosity liquid component, such
as a binder. This leaves gel particles that do not easily break down during
high resin content speciality coatings it is often not possible to grind, or
mix a formulation at high shear. The solution is to avoid formation of a gel
structure in the Laponite® pre-mix, either by using a glycol to “de-gel” the
mixture and make a temporary sol dispersion, or use a sol forming grade, e.g.
mixing speed when the Laponite® dispersion was combined with other
components. When a Laponite® dispersion comes into contact with materials
such as emulsion resins, a rapid increase in viscosity can occur, which can
cause the formation of localised gelling. As mixing continues, the gel forms
into seeds that do not easily break down during mixing.
that rapid and efficient mixing is used during the combination of the
Laponite® pre-mix and the other components of the paint.
paint contains an ingredient, which is incompatible with Laponite®, such as
TEA or NMP
is a highly anionic material and will co-flocculate with materials that have
a strongly cationic nature, such as tertiary and quaternary amine compounds.
The problem can be avoided by using primary or secondary amines to neutralise
resins, or by ensuring that neutralisation is completed before combination of
Laponite® with the resin- containing part of the formula.
23. What’s the difference between RD/ XLG and
RDS/XLS? Laponite® RD & RDS are designed for use in
industrial applications. Laponite® XLG and XLS are designed for use in skin
contact applications. In chemical terms, RD and XLG are the same as each other,
as are RDS and XLS. The significant difference is that products that are
designated “XL” are manufactured on a dedicated manufacturing stream, designed
for making products suitable for supply to the personal care industry. This
ensures that “XL” products have minimum bacteriological content, very low heavy
metal content and are free from contamination with foreign material
24. Which CMC type gives best synergy with
Laponite®? Using Laponite® in combination with CMC can produce
large synergistic increases in viscosity development. A higher level of synergy
is seen with medium and high viscosity CMC grades.
25. I have made a dispersion of Laponite® RDS/ XLS/
S482 in water and it does not form a gel. Why? Laponite® RDS/ XLS/ S482 products are sol-forming
grades and have been designed not to gel, or thicken in water. These grades
contain a dispersant additive that prevents gel formation in water only and so
allows relatively concentrated (up to 10% solids content for RDS & XLS and
up to 25% solids content for S482) liquid pre-mixes to be prepared. When the
liquid pre-mix is added to a suitable formulation, such as paint or toothpaste,
the other ingredients in the formula will overcome the effects of the
dispersant and viscosity increase can occur. Sol grades are especially useful
in “water-lean” formulas that contain low amounts of free water. High solids
content liquid sol dispersions can be used to prepare coating mixtures to
produce antistatic treatments on paper and film.
26. Do I have to wait for Laponite® RD to gel before
I add it to my formula?
No. In fact, in some cases, it can be
difficult to incorporate Laponite® into a formula after if has become a gel.
For example, if a Laponite® pre-gel is combined with a low viscosity liquid,
such as an emulsion resin, it can be difficult to get a homogenous mixture
without very efficient or high shear mixing. Observing “gel-seeds” in the
formulation will often be a manifestation of this problem. For suggestions on
how to avoid this problem, click on: Why have I
got gel seeds in my paint containing Laponite®?
I thicken acidic products using Laponite®? Yes, with
care. Laponite® is a mildly alkaline material and is easiest to formulate at
neutral pH and the basic side of the pH range. However, when handled correctly,
it can be used to produce thixotropic rheology in, for example, skin creams at
pH 5.5, surface coatings at pH 3 and mineral acid based toilet cleaners at
pH<1. Guideline starting formulations are available on our web site www.laponite.com or request them directly from Rockwood by e-mail to firstname.lastname@example.org
is the highest level of conductivity/resistivity that you can expect to obtain
when making an antistatic coating on paper using Laponite®? At a coat
weight of 3 g/m-2, of Laponite® JS, with, e.g. an acrylic or SBR binder (100
parts Laponite® to 10-20 parts dry mass of binder), it is possible to obtain a
surface conductivity/ resistivity of 106ohms.cm-2
is the usual delivery form of Laponite® products? The usual
delivery forms for Laponite® are:
polyethylene lined cardboard cartons, shrink-wrapped 40 cartons to a pallet
and 1000kg woven polypropylene IBC (big bag), shrink-wrapped to a pallet
weights can be supplied to order in IBC’s
SL25 is supplied as a liquid dispersion…”Liquid Laponite”… 1000kg packed in an
is the best pH range for Laponite®? Laponite® is
a mildly alkaline material and is easiest to formulate at neutral pH and the
basic side of the pH range. However, when handled correctly, it can be used to
produce thixotropic rheology in, for example, skin creams at pH 5.5, surface
coatings at pH 3, mineral acid based toilet cleaners at pH<1. Guideline
starting formulations are available on www.laponite.com or request them directly from Rockwood by e-mail to email@example.com
is the effect of temperature on Laponite® viscosity? Laponite®
creates viscosity using a mechanism based upon electrostatic attraction of
particles; the strength of these attractions is not affected by changes in
temperature. As a result, the viscosity of the Laponite® structure does not
change with temperature. However, in a formulated product, the viscosity of
other components may change; usually viscosity is lowered as temperature
increases. The viscosity of gums and polymers does change significantly as temperature changes. These materials thicken using
forms of covalent bonding; such bonds reduce in strength as temperature
increases. As a result, the viscosity of systems based upon gums and polymers
will reduce as temperature increases.
are the typical dimensions of a single crystal of Laponite®? When it is
fully dispersed in water, Laponite® particles are in the form of disc-shaped
nano-sized crystals. Type 1 products, e.g. Laponite® B, JS, XL21 are typically
~40nm diameter and ~1nm thick. Type 2 products, e.g. Laponite® RD, RDS, S482,
SL25, XLG, XLS, are slightly smaller at ~25nm diameter and ~1nm thick.
the word, “synergy” is used in relation to an interaction between Laponite® and
another raw material, what does this word mean? Firstly, a
wider definition of synergy…the potential ability for two or more materials when
used together to develop an increase in one or more properties that is greater
than might be predicted from observing the behaviour of the materials when used
on their own.
demonstrate synergistic interactions with a wide range of co-thickeners. A
common occurrence of this is viscosity synergy, which
occurs in combinations of Laponite® with CMC (sodium carboxymethyl cellulose)
to produce cost savings as a result of higher levels of viscosity build in
formulations such as toothpaste. Another form is electrolyte tolerance
synergy that occurs in combinations of Laponite® with xanthan
gum. With this combination, it is possible to formulate products across the
entire pH range, hydrochloric acid based toilet cleaners at pH 0.1, rust
conversion coatings at pH 3, facial moisturisers at pH 5.5, emulsion paints at
pH 8, household detergents at pH 9-10, depilatories at pH 12 and caustic oven
cleaners at pH 14. Starting formulations for all of the above are available
from Rockwood. Contact us on firstname.lastname@example.org with your
is the specific density of Laponite®? The specific density of Laponite® is 2.53. The bulk, or packed density of
powder grades is typically 0.95- 1.00 kg.dm-3. The bulk density of Laponite®
SL25, which is supplied as a 25% solids content dispersion in water is
typically 1.15- 1.20 kg.dm-3.
a sol grade?
The group of gel forming grades,
e.g. Laponite® XL21, RD and XLG are based on 100% synthetic layered silicate in
composition. Sol grades are synthetic layered silicate modified with
addition of dispersants. These are chemicals that have the effect of preventing
formation of a gel structure in water; such a low viscosity (liquid) dispersion
of a colloidal material is defined as a sol. Dispersions of
sol grades can be activated by addition of the aqueous dispersion into a
formulated product such as paint or toothpaste. More information is given on
this on pages 20 & 21 of the Laponite® Technical Brochure. This is
available at the following web link: http://www.laponite.com/pdfs/laponite.pdf
are two types of Laponite® sol forming grades- “temporary” and “permanent”.
Temporary sol forming grades
(P2O7)4- + 2OH- " 2(PO4)3- +H2O
dispersant used in e.g. Laponite® RDS, XLS or JS is tetrasodium pyrophosphate
(Na4P2O7). Under manufacturing conditions,
dispersions of these grades should be regarded as a temporary intermediate. The length of time for which a sol can
be stored is known as its sol stability. The
pyrophosphate ions which stabilise the Laponite® sol dispersion are themselves
unstable in solution and slowly hydrolyse to produce simple phosphate:-
charge density on the phosphate ion is much higher than on the pyrophosphate
ion and does not produce a sol stabilising effect. As the edges of the crystals
are once more free then particle-particle interactions can occur between
positively charged edges and negatively charged faces. This reduces the
mobility of the particles within the dispersion resulting in an increase in
viscosity - when the process is complete a highly thixotropic gel is formed. The
length of time for which a sol remains stable, at low viscosity, depends upon a
number of factors:
Concentration• as concentration increases then Laponite® crystals are forced into closer
contact with each other and viscosity increase will occur
temperature• at elevated temperatures the rate of hydrolysis of
pyrophosphate ion is accelerated and sol stability can be significantly reduced
level/water hardness• concentrated sols show maximum sol stability when deionised or soft water
is used- in harder water, sol stability may be reduced
soluble compounds (such as surfactants, polyols, simple electrolytes) or
latexes are added, then in some cases sol stability may be reduced. The
addition of larger quantities of electrolyte such as would be caused by
addition of the sol to a toothpaste or paint formulation will cause almost
instantaneous viscosity increase.
Typical stability of temporary sol forming grades
% concentration of the sol in water
At the concentration shown the
grade will be a stable sol for…
Laponite® sol stability is
defined as the time in days for which the sol continues to have a viscosity
of <100cP (Brookfield LV, 60rpm, 25ºC)
Permanent sol forming grades
grades, Laponite® S482 (supplied as a power) and Laponite®
SL25 (supplied as a ready-to-use liquid dispersion at 25%
solids content), are modified with patented dispersant
additives. Under normal conditions, sol dispersions of up to 25% in water, of
these grades will remain stable for over 1 year and can be regarded as
“permanent” sols. The patented additives used in these grades form stable
complexes at the edges of the Laponite® crystal, ensuring that aqueous
dispersions remain at low viscosity for very long periods of time. On addition
to a wide range of formulated products, they behave in the same way as
temporary sol forming grades- a rapid increase in viscosity will occur.
is the cation exchange capacity (CEC) of Laponite®? For Type1 products, Laponite® B, XL21, JS, CEC is typically 90 to 100
For Type 2 products Laponite® RD, XLG, RDS, S482, XLS, CEC is typically
50 to 60 meq/100g.
Laponite® compatible with cationic surfactants? Laponite® products are anionic materials and will normally co-flocculate
with cationic surfactants.
I use Laponite® to make conductive/ antistatic paints? Laponite® particles are intrinsically conductive and the product is
widely used to make conductive/ antistatic treatments on surfaces such as paper
and polymer films. In order for Laponite® to be an effective conductivising
agent it must be present as the main component in the coating formulation. A
typical conductivising formulation would contain 100 parts Laponite® JS to 10 –
20 parts emulsion resin binder at a total solids content of ~20%. When such a
coating is applied onto a surface and dried, it ensures maximum and intimate
contact of Laponite® particles with each other. As a result of this, the film
is conductive. However, when Laponite® is included as an additive in a paint
formulation, at e.g. <1%, then the other particulate components in the
formulation, such as resins, fillers & extenders, will act as insulators
and prevent the Laponite® particles coming into close contact with each other.
As a result of this, combined insulation & dilution effect, Laponite® does
not cause the paint to be conductive.
I prepare a dispersion of Laponite® JS at 20% solids content, what would it
look like after 1 day? It would be a translucent, low viscosity liquid, <100cP.
I have made my formula, I see a gradual increase/ reduction in viscosity. Why? There are many reasons why the physical stability of a formulation may
show changes after preparation. Click on the following link for a trouble
shooting checklist, which will open up in this file:
Laponite®: A trouble shooting checklist and how to achieve optimum performance
This will help you to determine if the problem is related to the use of
Laponite® in the formula. If these suggestions do not resolve the problem,
please contact us for a more detailed discussion by e-mail at: email@example.com
Laponite® slow down rate of drying of a coating? Unlike many organic polymers, Laponite® does not have a mechanism to form
hydrogen bonds with water and so does not slow down rate of drying to the same
degree as many other thickeners. Laponite® does increase rate of drying when it
used as a “set-up” agent to control rheology in ceramic glazes. The very high
degree of shear thinning that is developed in systems that contain Laponite®
ensure the water in the glaze formulation is absorbed rapidly in a ceramic
piece as viscosity of the glaze is reduced by the shear stress created by
capillary action that is generated at the surface of the ceramic piece.
level/type of surfactants can be used with Laponite®? When handled in an appropriate manner, it is possible
to thicken some systems that contain >30% active surfactants using
Laponite®. However, in other systems, just a few per cent of surfactant may
cause loss of viscosity. The very large ranges of different types of
surfactants that are available make this a difficult question to answer other
than in very general terms.
Some guidelines are given below:
increases in surfactant tolerance/ compatibility can often be developed by
using Laponite® in combination with selected co-thickeners, such as some grades
of xanthan gum or polyacrylate additives. This can allow preparation of
relatively high surfactant content products, which can hold suspended actives,
or, which are sprayable.
is anionic in nature and will co-flocculate with cationic surfactants. It is
recommended that Laponite® products are not used for rheology control in
formulations that contain cationic components.
will behave differently with mixtures of surfactants and other formulation
additives than it will in simple combinations of Laponite®, water and
surfactants X or Y. In many cases, it can show better compatibility with
surfactants in complete formulations than it does in experiments to test
compatibility with a single surfactant at a range of concentrations.
For additional help with using Laponite® in your own formulation, you are
requested to contact us, by e-mail at: firstname.lastname@example.org
is the refractive index of Laponite®? The refractive index of Laponite® is 1.5.
is the shelf life of Laponite®? The shelf life of Laponite® products is a minimum of two years from date
of delivery, if stored as directed and in original packaging.
is Laponite® made? Laponite® products are made at Rockwood Additives Limited, Moorfield
Road, Widnes, Cheshire WA8 3AA, United Kingdom. Rockwood Additives Limited is
part of Rockwood Specialties Group Inc., a world class speciality chemical
company, headquartered in Princeton, New Jersey USA. For more information, go
to http://www.rockwoodadditives.com/ and http://www.rockwoodspecialties.com/index.htm.
you give guidelines on the best way to disperse Laponite?
How to disperse Laponite®: As with most speciality
additives it is critical that Laponite® is introduced into formulations in the
correct way. This will ensure that optimum performance and efficiency is
achieved. All Laponite® products both gel forming and sol forming, must be
added to water and allowed to disperse and hydrate fully before any other
components are added. The presence
of components such as surfactants, dispersing agents etc., already in solution
will interfere with the dispersion of Laponite® and in some cases may halt it
For gel forming grades and
temporary sol forming grades
Add the free flowing Laponite® powder
to deionised or tap water at room temperature (15-25°C) with rapid agitation.
Mixer speed should be sufficiently high to produce a vortex which will cause
all the powder to fully wet out without the formation of clumps. Suitable
laboratory mixing equipment could be a mechanical stirrer fitted with a propeller
blade revolving at 200rpm or a saw tooth (Cowles) blade revolving at 500rpm.
Mixing should be continued for at least 20 minutes. If required, dispersion
time may be reduced by increasing the temperature of the mixture up to 40-50°C
after the Laponite® powder is fully wetted out or by use of a high shear mixer
such as a Silverson. The viscosity of the Laponite® dispersion at this time
depends upon the concentration of the premix and the Laponite® grade in use.
The typical use level of Laponite® in a formulation may range from 0.05% up to
1%, or higher in some cases.
What’s a sol grade?- Click here for more information
For gel forming grades RD,
XLG, D, DF
When dispersion is complete these grades produce a clear, colourless
colloidal dispersion. Concentrations above 3% of gel forming grades can build
structure very quickly in the Laponite/water premix and will form a highly
viscous pregel which can make it difficult to incorporate with other raw
materials in a formulation. If insufficient free water is available to allow
the preparation of a premix with concentration below 3% then Laponite® may be
“de-gelled” by the addition of compounds such as tetrasodium pyrophosphate or
low molecular weight polyethylene glycols. This de-gelling effect is overcome
on addition of the premix to a formulation.
For temporary sol forming
grades RDS, XLS, DS, S, JS
Colourless, translucent and colloidal, low viscosity dispersions known as
sols are formed. This liquid premix may be stored and used in successive
batches of a formulation. High solids concentrations of sol grades should be
aged for up to one hour to allow the hydration process to complete.
For permanent sol forming grade S482 To produce a sol at 20% solids or higher, use similar mixing equipment to
that described above for gel and temporary sol forming grades…a mechanical
stirrer fitted with a propeller blade revolving at 200rpm or a saw tooth
(Cowles) blade revolving at 500rpm. Add the free flowing Laponite® powder
quickly to deionised or tap water with rapid agitation at room temperature.
Mixer speed should be sufficiently high to produce a vortex which will cause
all the powder to fully wet out without the formation of clumps.
At very high solids content with Laponite® S482, there will be a rapid
increase in viscosity of the mixture to produce a thick, paste-like texture within
a few minutes. At this time turn off the mixer and allow the dispersion to age
for up to one hour to allow the peptising effect of the patented additive to
develop. The viscosity will fall rapidly during this time. Turn the mixing
equipment back on and continue mixing for a further 30 minutes. Sols of Laponite®
prepared in this way may be stored for very long periods of time before use.
Laponite® SL25 is supplied as a ready-for-use liquid
47. What toxicology and regulatory
information is available for Laponite® products? Toxicology and regulatory information on Laponite® products
is summarised in Laponite® Technical Bulletin L246,
Summary of regulatory information, nomenclature and toxicity studies relating
to Laponite® products. This bulletin is produced as a supplement to the Safety Data Sheets and Product
Data Sheets that are available for the range of Laponite® products. The
bulletin may be used together with these Data Sheets to assist in carrying out
a safety assessment or to determine the suitability of using Laponite® in an
Technical Bulletin L246, Laponite® Safety Data Sheets and
Product Data Sheets can be downloaded from our web site: www.laponite.com. From the home
page, click on the Technical
Information button and then select MSDS or PRODUCT BULLETINS from the menu
can I find information on Optigel® products? Rockwood purchased the Optigel® range of products from
Süd-Chemie AG in January 2006. The so-called “Optigel S” series of synthetic layered silicates is now offered under the Laponite® brand name. Optigel® SH
has been replaced by Laponite® RD; Optigel® S482 is re-named Laponite® S482; a
liquid dispersion of Laponite® S482 at 25% solids content is offered under the
grade name, Laponite® SL25. Page 4 of the Laponite® Technical Brochure gives more
information on the range of Laponite® grades. This is
available at the following web link: http://www.laponite.com/pdfs/laponite.pdf
Other Optigel® grades, based upon natural layered silicates, such as Optigel® CK, Optigel® CG, Optigel® WX, Optigel® WA,
etc. continue to be offered by Rockwood. Visit www.optigel.com for more information on the range.
other rheological additives are available from Rockwood? Our range includes the following:
- Purified bentonites for water based systems: Bentolite®,
Gelwhite®, Mineral Colloid®, Optibent®, Optigel®
- Organoclays & castor derivatives for solvent based
systems: Claytone®, Garamite®, Tixogel®, Rheocin®
- Associative thickeners, non-ionic alkali swellable
polymers: Optiflo®, Pure Thix®
- Nano-structuring agents for use in polymers: Cloisite®
For more information visit www.scprod.com and click on OUR PRODUCTS.
is “Liquid Laponite®”? Laponite® SL25 is a ready-for-use low viscosity
aqueous dispersion of Laponite® at 25% solids content. Product development work
is underway to make Laponite® grades that remain stable as low viscosity
dispersions in water for longer periods of time and at higher solids content.
Such materials have often been described as “Liquid Laponite®”
can I order Laponite® samples/ get formulation or handling recommendations? The e-mail address email@example.com will connect you with our team of experienced technical specialists. Rockwood
can provide useful formulation advice and handling recommendations, which can
often assist our customers in shortening development times for their own new
products. You can also use this e-mail address to request samples, or to make
any commercial enquiries. Alternatively, contact us by telephone or fax at one
of the addresses below:
|Rockwood Additives LimitedMoorfield Road WidnesCheshire WA8 3AA United KingdomTel: +44 (0)151 495 2222Fax: +44 (0)151 420 4401
||Southern Clay Products, Inc.1212 Church StreetGonzales, Texas 78629 USATel: Toll Free 888-LAPONITEor dial 830-672-2891Fax: 830-672-1903
|Rockwood Clay Additives GmbHStadtwaldstrasse 4485368 MoosburgGermanyTel: +49 (0)8761 72150-0Fax: +49 (0)8761 72150-393
Specialties (Singapore) Pte. Limited171 Chin Swee Road Unit No: # 10-08
San Centre Singapore 169877Tel: +065 6532 0676 Fax:
+065 6532 0502
Laponite® is a registered trademark of Rockwood
Additives Limited. All
information here is given in good faith but without warranty or guarantee of
any kind whatsoever, whether implied or expressed. Freedom from patent rights
must not be assumed. This file does not form part of the conditions of sale, is
of a general nature and should not be used as the basis of a specification.