The role of rheology modifiers in texture coatings

THE ROLE OF
RHEOLOGY MODIFIERS
IN TEXTURE COATINGS
By Engr. Zenith F. Czora, ChE, ATSC

WHAT IS A TEXTURE COATING?
an important segment of surface coatings industry
for the domestic, commercial and industrial
markets.
They enhance or add specific character to a
decorative wall or ceiling. Aside from creating a
pleasing patterned finish, texture coatings
depending on its flexibility properties, are also
used to bridge cracks and hide imperfections on
the substrates.
Pigmented texture finishes, can be classified into
three types: trowelled finishes, spray on and
roller-applied finishes.

THREE CATEGORIES OF TEXTURE COATINGS
CATEGORIES DESCRIPTION
Ready Mix
Texture Coating
a paint of heavy consistency and fine to coarse grain consisting
usually of fillers, and varying sizes of aggregates, with water-
thinned binder and used for creating a rough patterned effect
on a wall
Cementitious
Texture Coating
can be a single pack dry mix or can be a two pack system. The
single pack acrylic/cement hybrid dry mix contains the
dispersible polymer, cement, sands, fillers, dispersible coloured
pigments, aggregates, rheology modifiers and some functional
additives. Two–pack cementitious texture coating consist of
dry powder which is the cement or cement/sand/fibres
/thickener mixture and the liquid part which contains the
polymer binder, pigments, fillers, quarts, marbles, rheology
modifiers and additives.
Acrylic Powder
Texture Coating
based on dispersible polymer powders with dispersible
coloured pigments, selected fillers, graded sands, marbles or
quartz for texture effect, specific additives and rheology
modifiers to achieve the desired look and ease of application

HOW THEY ARE APPLIED?
they are either trowelled onto the substrate and finished off using a
plastic float for an even packed flat render finish,
or using a polystyrene float, resulting in a “scratch” (or “scored”)
finish,
or rolled on using an open weave roller to produce a rippled or
peaked effect,
using sponge or lambswool mitt for bagged look,
 using tempering brush for distempered or swept effect,
Long nap roller to give a scattered sandy grainy effect can apply
some texture coatings.
Another method employed was to roll using a texture roller (type
of texture roller to be used is depending on the fineness and
coarseness of aggregates of the texture coating) onto the wall and
finish off with the polystyrene float.
Using a hopper gun for spray on application and can be flattened
using a polystyrene float.

TOOLS USED FOR TEXTURE APPLICATIONS
STEEL TROWEL PLASTIC FLOAT POLYSTYRENE FLOAT
BLACK TEXTURE ROLLERHAWK

SPAGHETTI
ROLLER
DISTEMPER BRUSH LAMBSWOOL MITT
HOPPER GUN SPONGE

HOW THE TEXTURE COATING IS
FORMULATED AND MADE?
CRITERIA OF TEXTURE COATINGS:
TOUGH, AND DURABLE FILM
WATER RESISTANCE
ATTRACTIVE DECORATIVE FINISHES
HIGH SOLIDS - TO MINIMIZE SHRINKAGE
FLEXIBLE

COMPONENTS OF A TEXTURE COATING:
 Binder - 100% acrylic resins and or styrenated acrylic polymer
 Dispersant - needs to be chosen carefully to maximise storage stability and
minimise water sensitivity
 Coalescing Solvent - level and type to be considered on the effect on drying and
surface cracking when applied on extreme temperature conditions
 Wet Edge extender – e.g.. Propylene glycol at minimal level to maintain wet-edge
and to prevent excessive through-fry times.
 Inorganic pigments and coloured stones - to colour the finishes and for ‘multi
colour’ granite finish
 Titanium dioxides - same type used in flat finishes
 Tinters – durable tinters excellent weather resistance and lightfastness, but in
minimal amount not to affect the application properties and water resistance of
the coating
 Fillers/Extenders - particle size distribution are optimized for well balance
pigment packing and to prevent film checking or microcracking
 Aggregates – graded sands, quartz, pebbles- to be chosen carefully to produce a
tightly packed coating , the size of the aggregates determines the application
thickness for “scratch finish”
 lightweight fillers and fibres - to minimize shrinkage and micro cracking

EQUIPMENTS & MANUFACTURING METHOD
MILLBASE PART:
 DISPERMAT & COWLES HI-SPEED DISPERSER
 BINDER/EMULSION, DILUENT, ADDITIVES, DISPERSANT
,PIGMENTS, & FILLERS
 OPTIMIZATION OF MILLBASE CONSISTENCY OR DILATANCY FOR
MAXIMUM GRINDING EFFICIENCY BY ADDING CLAY OR
CELLULOSIC THICKENER
LETDOWN PART:
 EDGE-RUNNERS OR RIBBON BLENDERS
 SLOWER MIXING SPEED
 CHARGING OF REMAINING BINDERS/EMULSION
 PUMPING OF THE DISPERSED MILLBASE INTO RIBBON BLENDER
 ADDITION OF ADDITIVES, THEN AGGREGATES ACCORDING TO
SIZES AND LIGHTNESS
 ADDITION OF RHEOLOGY MODIFIERS

CHOICES OF RHEOLOGY MODIFIERS:
FUNCTION OF RHEOLOGY MODIFIERS:
 RESTRICT THE MOBILITY OF A MATERIAL IN A LIQUID MEDIUM
 GIVE THE REQUIRE BALANCE OF APPLICATION PROPERTIES:
 ROLLER LOADING
 HOLD UP
 SPATTER RESISTANCE
 SAG RESISTANCE
 SLUMP RESISTANCE
 FLOW & LEVELING PROPERTIES
 FILM BUILD
 PROVIDE BALANCE OF IN-CAN VISCOSITY, CONSISTENCY,
APPLICATION VISCOSITY, ANTI-SETTLING PROPERTIES

•Slow viscosity recovery gives good levelling, and gloss
but the paint may sag on vertical application
•Fast Viscosity recovery reduces flow, provides high film
builds and peaky profile, prevents occurrence of sagging
but may cause brush marks
EFFECT OF VISCOSITY RECOVERY AFTER REMOVAL
OF SHEAR FORCE ON THE DESIRED PROFILE FINISH:

Type of Viscometer Type of Viscosity
Brookfield viscometer Low and medium shear
viscosity
Stormer viscometer Medium shear rate
viscosity ( in-can
viscosity)
ICI cone and plate High shear ( flow ,
levelling and film build)
Rheometer Low to high shear
viscometer
LIST OF DIFFERENT VISCOSITY MEASURING DEVICE AND
WHAT TYPE OF VISCOSITY THEY MEASURE:

PAINT FLOW PROPERTIES
INFLUENCED BY TYPE OF THICKENERS:
1. Levelling - The use of low molecular weight associative thickeners
& A high shear thickener
2. Brush drag and film build - HEUR, HEAT, Polyether urea
polyurethanes (PEUPU) and hydrophobically modified alkali
swellable emulsions (HASE)
3. Sagging and Slumping - ASE with pseudoplastic behavior,
Associative thickeners that increase the elastic modulus ,
Hectorite clays
4. Spattering characteristic – Associative thickener, HMHEC
5. Anti-settling and Syneresis - Clays and organoclays , Associative
thickeners
6. Colour Acceptance, Colour Float and Colour Stability - Polyether
polyol type thickeners and HEUR
7. Coating “Pick-up”/Loading – HEUR, Clays, HMHEC
8. Workability - Clays, Cellulosic

TYPES OF RHEOLOGY MODIFIERS, THEIR USES, BENEFITS AND LIMITATIONS THAT ARE
COMMONLY USED IN TEXTURE COATINGS
TYPES OF
THICKENER
DESCRIPTION BENEFITS LIMITATIONS
Cellulose
Ethers :
Hydroxyl ethyl
cellulose
(HEC), Methyl
cellulose
(MC),
Hydroxypropy
l methyl
cellulose
(HPM),
Sodium
carboxyl
methyl
cellulose
(SCMC)
Derived from
cellulose, a naturally
occurring
polysaccharide
found in cell walls of
plants and woody
species. Its
thickening effect is
mainly due to
rheological
immobilization of
significant amounts
of water, which
hydrate
macromolecules
and remain intact
but immobilized
(hydrodynamic
mechanism)
 Provide reasonable
properties for most type
of paints as a single
thickener.
 Provides good resistance
to sagging, and syneresis
 Retains water in partially
coalesced film better
than ASE/AT, leading to
reduced problems with
mud-cracking
 help to stabilize
pigments and extenders
 improve colour
development
 increase open time
 Offer a wide range of
application
 Shear thinning for easy
application
 Thickens the water phase only excluding the
disperse phase. This force the pigments
particles close together, increasing the
probability of flocculation and lowering
gloss.
 Decreases the water resistance of paints,
reducing the washability and scrub
resistance.
 Generally poor flow compared to associative
types
 Generally low film builds.
 Prone to bacterial growth in the can,
resulting to loss of viscosity and foul odours.
 poor spatter resistance and anti-settling
properties
 elevated hydrophilicity (resulting in
decreased scrub-resistance, wet adhesion
and film softening)
 relatively slow viscosity development
 Like any non-ionic polymer, the interaction
with water of HEC and the other non-ionic
cellulose thickeners decreases with
increasing temperature. For the majority of
grades, loss of efficiency occurs when the
temperature exceeds 30 -40 °C

TYPES OF
THICKENER
Modified
Alkali Soluble
Emulsion
(ASE)
By incorporating acid groups
onto the backbone of an acrylic
polymer chain, anions are
provided, creating a water-
soluble molecule, which provides
thickening due to hydrodynamic
expansion. Comprised of acid-
containing acrylic emulsion
copolymers that are supplied at
high solids and low viscosity.
When neutralized with an alkali,
these products become clear,
highly viscous solutions. This
neutralization can be
accomplished before or after
addition to the formulation.
these products can be easily
blended to obtain intermediate
rheologies
 Generally low
cost
 Low supplied
viscosity/high use
viscosity
 Biologically stable
 Good sag/slump/
settling/syneresis
resistance
 Excellent for
texture paints,
texture finishes
or sealants for its
profile build ups
 Sensitive to
electrolytes
 Generally poor flow
 Need to handle base
( ammonia)
 More porous film
compared to ATs
 pH sensitive and
dependence
 generally inefficient
at high shear rate
 generally poor water
and alkali resistance
 Moderate efficiency
 Limited film build

TYPES OF
THICKENER
Hydrophobical
ly-modified
Alkali Soluble
Emulsions
(HASE)
Refined version of
ASE thickeners by
incorporating
hydrophobic
monomers onto
some of the
branches of an
ASE thickener,
which provides an
association site
for interaction
with hydrophobes
on the latex
particles, or other
components of
the dispersed
phase.
 Generally low cost
 Low supplied
viscosity/high use
viscosity
 Viscosity stability in the
presence of electrolytes
 Biologically stable
 Improved film
build/flow and levelling
versus HEC/ASE
 Spatter resistance
versus HEC/ASE
 They can be used with
high adhesion paint
grade latexes that are
relatively hydrophobic,
or more hydrophilic-
larger particle size
latexes, to obtain a very
good balance of cost
and performance.
 Strong shear thinning
 Relatively poor water/alkali
resistance due to its alkali
sensitivity by nature
 Surfactant sensitive
 Less effective with larger
particle-size emulsions or at
lower volume solids.
 pH sensitive or significant pH
dependence. Their maximum
thickening efficiency is in the
pH range of 7.5 -8.5.
 need to handle base
 May interact with some
dispersants causing pigment
flocculation or loss of gloss or
viscosity.
 Some types causes colour
acceptance problems with
colourants
 Greater skill and care necessary
for selecting the proper
modifier

TYPES OF
THICKENER
Hydrophobica
lly-modified
Ethylene
Oxide
Urethane
Rheology
modifiers
(HEUR) – non-
ionic urethane
associative
thickeners
Interact solely by
adsorption/association
with other
hydrophobes in the
formulation. The main
thickening mechanism
is the association
between the thickener
and the
binder/pigment colloid
particles. HEUR
associative thickeners
are typically low
molecular weight and
highly associative
thickeners that provide
a well balance rheology
properties depending
on its individual
rheological behaviour.
 Depending on type can provide Newtonian or
pseudoplastic characteristics
 can provide excellent flow and levelling, uniform
film formation and high film build
 allows excellent sag resistance with minimal effect
in flow and levelling
 Near alkyd flow/ application properties
 High gloss obtainable
 Control of spreading
 Improved water/alkali resistance
 Resistance to biological degradation
 Constant viscosity performance at any pH
 Resistance to hydrolysis
 Viscosity stability in the presence of electrolytes
 Low supplied viscosity/ high use viscosity
 Improved durability on exterior exposure or under
corrosive conditions due to uniform, high film build
 Excellent roller spatter resistance
 Improve brush/roller loading, good anti-drip
properties
 Provide good in-can structure and good anti-
settling properties
 Give excellent roller pattern and reduce roller
slippage
 Provide superior spray application properties
 They do not require alkali neutralization for
thickening and can provide excellent resistance
properties.
 They are easy to handle and incorporate in the
manufacturing process.
 Less effective at low volume
solids or with large particle size
emulsions
 Sensitive to
surfactants/glycols/dispersants-
lose viscosity on tinting, making
them unsuitable as sole
thickeners in deeptones
 Some types can be difficult to
handle/incorporate
 Some formulations maybe
subject to long (but predictable)
viscosity equilibrium times
 Some types have their
inclination to phase separation
 sensitivity to formulation change
 lifting of aged undercoats
 Lesser degree of sag control
 Greater skill and care necessary
for selecting the proper modifier
 More expensive than cellulosics,
ASE, or HASE

TYPES OF
THICKENER
Hydrophobi
cally
Modified
(HM)
Hydroxyeth
yl Cellulose
(HMHEC)
Has a lower
molecular
weight than
typical
grades of
HEC, while
maintaining
thickening
efficiency
 enhanced brushing viscosity,
 greater film build, better hiding
and less dirt retention
 better flow and levelling w/
excellent sag resistance versus
HEC,
 outstanding roller spatter
resistance versus HEC/ASE
 More Newtonian flow profile
versus HEC
 Reduced viscosity loss on tinting
versus other AT
 Excellent in-can stability, less
pigment and latex flocculation,
less syneresis
 Excellent colour acceptance and
colour development
 Wide compatibility with latexes,
pigments and surface-active paint
components
 Still prone to
biological
degradation
 Less effective at
low volume solids
or with large
particle sized
emulsions

TYPES OF
THICKENER
Clays and
Modified
clays (
Montromo
rilonite/
Attapulgite
/
Hectorite/
Smectite/B
entonite)
Refined naturally
occurring clays
possess and
expandable crystal
lattice, polar in nature,
which will absorb
water to form a gel.
The modified clays are
from pure clays being
modified with suitable
polymers to achieve
the ideal flow for a
specific application.
Clays are used to
adjust flow properties
in the low-shear range
and to provide a slight
pseudoplasticity or
thixotropy, to control
setting, film thickness,
and sagging.
 Imparts thixotropy, high viscosity and quick
rheology recovery after shear is removed
 Impart a yield stress
 Prevent settling or creaming
 Provide sag/drip resistance and slump
resistance
 Excellent pigment suspending agent, reduces
syneresis, minimizes floating/flooding of
pigments
 provide wet-edge/open time, improves water
retention of plasters
 does not retard drying; has consistent water
release
 improves wash and scrub resistance of paints
 compatible with most non-ionic and anionic
wetting agents/surfactants
 Generally non-yellowing
 pH stable (3-11)
 Bacteria- and enzyme -resistant
 Relatively low cost
 Comes in powder form or in gel form
 Can thicken solvent-based system
 Offers good spatter resistance
 Rarely used as a sole
thickener, generally
used as an auxiliary
thickener to other
types
 Takes some skill to
disperse directly into
millbase correctly or
to handle pregels
 Decrease gloss
 Require both wetting
and shear to
delaminate properly
and develop their
fully rheological
active state.

TYPES OF
THICKENER
Organic
titanates (
titanium
chelates)
Used as structural
additives co-thickened
cellulosic thickener in
paints. Titanium
chelates work best
with latexes stabilized
by cellulose ether
colloids and thickening
is thought to occur as
the result of hydrogen
bonding between
hydroxyl groups in the
cellulose ether colloid
chains and hydroxyl
groups associated
with the titanium
chelate in its
hydrolysed form.
 Gives more attractive in-can
and application properties than
paints thickened solely with
cellulosic colloids
 Improves the water resistance
of cellulosic thickened paints,
increasing the scrub resistance
and washability
 Not affected by pH variations
 Improves resistance to
dripping, sagging, and
spattering
 Improves flow and levelling by
imparting thixotropy to
cellulosic-thickened systems
 Reduces the level of cellulosic
needed.
 Cannot be used with
latices stabilised by
polyvinyl alcohol
 Difficult to use with
surfactant stabilised
latex
 Gel formation
inhibited by
surfactants and glycols
and particularly less
effective in heavily
tinted systems
 Can’t be used as a
sole thickener
 Need to modify paint-
manufacturing
procedures to pack off
before paint develops
structure.

TYPES OF
THICKENER
Hydrophob
ic
Ethoxylate
d
Aminoplas
t
Thickeners
(HEAT)
Non-ionic and
emulsifier-free
thickener that
meet all shear
ranges and
primarily consists
of water-soluble
polyethylene
glycol, onto which
a few non-water
soluble
(hydrophobic)
molecules have
been added via a
patented
aminoplast
linkage.
 Impart excellent flow and
levelling and high film build,
 Creates excellent brush drag
 Reduces spattering
 Does not affect acceptance of
tint pastes
 Pseudoplastic/thixotropic
behaviour to prevent settling
 Increased resistance to water,
alcohol and liquid cleaners.
 Improved barrier effect
 Provides colour uniformity and
paint consistency (less
separation)
 Increased stability with respect
to pH fluctuations
 No syneresis and improved
storage stability
 No reduction in gloss and Haze-
free
 Wetting agents
influence the
thickening effect
of HEAT
 Higher quantity
needed for very
low solid paint
system.

TYPES OF
THICKENER
Polysaccha
ride
(Natural)
Xanthan
gum (an
anionic
polysaccha
ride)Gums
(an anionic
polysaccharide)
Gums, which
their mechanism
of stability
depends on the
nature of their
macromolecules.
Some adsorb on
the polymer-
water interface
while others
modify only the
aqueous phase
viscosity.
 Highly pseudoplastic
or shear thinning
 quick recovery once
shear force is
removed
 Have outstanding
stability with respect
to pH, salt or heat
 Excellent
compatibility with
other ingredients
 Readily soluble in
both hot and cold
water systems
 susceptible
to bacterial
attack
 requires
efficient
shearing in
high solid
system

TYPES OF
THICKENER
Fibrous
Rheology
Modifiers
inorganic
and organic
fibres
(glass,
polyolefin,
and aramid
fibres)
 Ability to interact with the
polymer matrix via dipolar
and / or dispersion
interactions
 Ability to achieve
polymeric entanglement
 improve crack resistance
and film shrinkage
 Effective suspending agent
for pigments (improved
particle suspension)
 Resistance to water
damage
 Imparts Fine Texture
(shorter finer grades) to
Medium / Heavy Build
(coarser, longer fibres)
 Viscosity control
 Takes some skill
to disperse
directly into
millbase
 Can’t be used as
a sole thickener
 Require both
wetting and
shear to
delaminate
properly

TYPES OF
THICKENER
Non-ionic
Synthetic
Associative
Thickener
(NSAT)
Are often used
in tandem with
other rheology
modifiers. build
rheology in
paints and
coatings
through self-
association and
interaction with
other
ingredients
 Easy-to-handle liquids
 Excellent spatter resistance;
 Excellent film build and favourable
brush drag
 can reduce KU driver demand
 Superior flow and levelling.
Optimise sag/levelling balance
 Full gloss development,
 pH insensitive,
 Bio stable, APEO-free and solvent-
free
 Good roller transfer and coverage,
resulting in a virtually drip-free
application and can deliver
improvement in substrate wetting
 imparts creamy in-can feel,
equilibrate rapidly in paint to final
viscosity with excellent long-term
stability
 is effective in a wide range of latex
chemistries
 to be
incorporated
into the paint
formulation
before the
addition of the
latex

WHAT WILL HAPPEN WHEN USING
THE WRONG RHEOLOGY MODIFERS ?
Occurrence of variety of film defects:
o fish eyes,
o wet-out problems on a substrate,
o flocculation.
o cause issues with production times when
added too quickly
With the wrong rheology modifier is used and it is
over-sheared, the paint will not recover in viscosity as
needed and will affect the final application to the
substrate.
Water Sensitivity

MOST COMMON TYPES OF TEXTURE COATINGS:
TROWEL-ON FINISH
– High build flexible texture coating filled with a range
granular aggregates
- It is applied using a hawk and stainless steel trowel to
the prepared substrate at a spread rate of 0.5 - 1.0 sq. m. per
litre.
- It is then floated using a plastic float or polystyrene
float
- Using a SCMC type cellulose thickener for easy transfer,
great hold up and with very little loss or no loss at all.
- It is co-thickened with hectorite/smectite clay and
polysaccharide gum for well balance workability on float
finishing.
- Cellulosic fibres can be added for crack resistance and
shrinkage.

ROLL-ON FINISH
- a high build coating that provide a render effect and both a fine
and coarse structured profile.
- The roll-on system is applied using a either a long nap roller for
render effect finish, Black Texture roller for fine to medium peaky profile
and Coarse Texture Roller or Spaghetti roller for coarse peaky profile.
-Rolled finishes must be easily workable and require less effort to
achieve a consistent pattern yet, once achieved, the finish must not slump
or lose the definition of peaks.
-Alkali-swellable emulsions with the combination of attapulgite
clays and methyl hydroxypropyl cellulose thickeners work well to provide a
texture profile.
-For render effect finish, a combination of hydroxyl ethyl cellulose
and HEUR that provides high low-shear viscosity is most suitable.
-For Medium Texture, combination of hectorite clay, CMC, HEUR,
and cellulosic fibres provide a balance film build of consistent sandy finish.

SPRAY ON FINISH
- A stipple sand finish Texture Coating is
achieved by spray application.
- Applied by a Hopper gun or Texture Spray gun
to achieve a granular mineral appearance
- The “2nd pass” stipple application delivers a
higher profile texture for greater substrate
hiding power.
- Any type of ASE and HEUR for spray application
combine with Hectorite clays will provide good
atomization and product delivery to the
substrate with good sag and slump resistance.

. Sponge/ Bagged/Swept Finish
– A granular, near flat, appearance very much
like that of a bagged finish render
- applied by long nap roller and finished by
sponge, lambs wool mitt, or distemper brush
depending on the desired texture finish.
- A combination of HMHEC, smectite clay,
polysaccharide gum and KU builder HEUR, will
provide a very good balance of low and high shear
viscosity for outstanding flow and sag resistance,
good roller loading, excellent spatter resistance,
and good workability.

SUMMARY:
- INFLUENCE OF SOLVENTS, POLYMER/BINDERS, EXTENDERS AND
PIGMENTS
- APPLICATION METHOD AND DESIRED PROFILE GOVERNED BY
COMBINATION OF TWO OR MORE DIFFERENT TYPE OF
THICKENERS
-METHOD OF INCORPORATION AND FINAL PRODUCTION TIMES
The final application answers three important
questions about the modifier selection:
1. WHAT MODIFIER?
2. HOW MUCH?
3. AND WHERE SHOULD IT BE ADDED?

THANK YOU!!!
Zenith F. Czora, BSChE, ATSC, is a licensed chemical engineer with technical
expertise in developing and formulating coatings products, coating specification,
SDS and GHS labelling, production scale-up, manufacturing process, quality control,
good laboratory practice, and products accreditation and certification. She has 27
years of experience in the coatings industry and specializes in the product
development and formulation of architectural coatings; texture coatings;
floor/sports surface coatings; membrane/elastomeric coatings; waterproofing
coatings; wood coatings; and automotive, industrial and marine coatings. She is
currently working at Parex Davco Australia as a Research & Development Chemist
specializing in waterproofing, floor coating and sealing, and tile grouts.

The role of rheology modifiers in texture coatings

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