Liquitex - Techniques

GENERAL
The products that generate the most technical questions are Gloss Medium & Varnish, Soluvar and Gesso.

Can I use Liquitex Acrylic s with other brand name acrylics?
Liquitex Acrylic Paint should be compatible with most other acrylic products, however the light fastness, flexibility, yellowing and UV protecting capabilities may vary from one product brand to another. Always do an adhesion test when using other products to determine compatibility.

Can Liquitex Acrylic Paint be used on top of latex paint?
Water-based emulsion acrylics belong to a larger group called latex. Most people however are referring to latex house paint when using the term latex. The binder and pigment qualities in these paints are not artists’ quality. House paint quality latex becomes brittle with age and is therefore not recommended for use under artists’ acrylics.

What does the word "hue" mean when it is included in the color name?
Some colors have a "hue" designation at the end of their name as in Cadmium Red Medium Hue. When used in this way, hue is not a color attribute but rather a replacement or alternate for a target color. The "hue" colors many times yield higher intensities at a lower cost for pigments that are unavailable, expensive or fugitive (not lightfast) or pose possible health hazards.

I am painting a sign, which will be placed outside permanently. How should I prepare the surface I am painting on to ensure the sign remains in good shape and can be cleaned?
Begin with a wood product meant for outdoor use such as MDO Board. This is a type of plywood that is bonded with paper on one or both sides, available from sign making supply houses. Apply 2 – 5 coats of Liquitex Gesso, sanding between coats. Once the painting is complete, allow 3 days drying/curing time. Coat with Liquitex GlossVarnish. Final varnish with Liquitex Soluvar (Matte or Gloss) or a water-based polyurethane varnish, such as ZAR® Exterior Water-Based Polyurethane (contains radiation absorbers to resist ultra-violet rays). Soluvar is a clear, flexible removable varnish with UV filters and can be removed at any time for cleaning with mineral spirits. Polyurethane is a more durable varnish but is not flexible or removable and may yellow over time. Varnish both sides and edges to seal against moisture.

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COMPONENTS

What is acrylic paint?
Acrylic paint begins as a water-based (as opposed to solvent-based) emulsion composed of minute acrylic resin spheres suspended in water. Pigment is then added to produce a colored paint. The synthetic resin is composed of an acrylic polymer or blend of polymers (organic materials made from natural gas) which does not dissolve in water. Through the use of surfactants (an agent that aids in wetting out and dispersing dry pigments to a liquid), the polymer is suspended in water creating an emulsion. Milk is an example of a natural emulsion where the fat particles are suspended (not dissolved) in water. As the water evaporates in acrylic paint, the resin spheres are drawn closer, until they touch and fuse together. This is coalescence and produces a honeycomb like pattern. Pigment particles are trapped in the honeycomb pattern, producing a paint film that is highly flexible with great adhesion.

Why is it important for an acrylic paint to use a high quality acrylic resin?
The quality of acrylic paint is to a large degree determined by the quality of its resin base.
This determines paint aspects such as handling characteristics, clarity, flexibility, UV resistance (non-yellowing), drying, and curing times, and archival charateristics.

What is the difference between organic, inorganic, natural and synthetic pigments?
Pigments are dry, powdery materials, which do not dissolve, but remain dispersed or suspended when mixed with a liquid (i.e. acrylic polymer emulsion). They are either organic, inorganic, natural or synthetic. They have little or no affinity for the surface onto which they are applied and a binder is necessary to adhere the pigment to the painting surface and coalesce into a paint film. There are four types of pigments:

Pigment Source Attributes Examples
Natural
Organic Carbon based. Vegetable or animal. Transparent, high tinting strength, varied lightfastness Sepia, Ivory Black
Synthetic
Organic Carbon based derivatives. Transparent, high tinting strength, excellent lightfastness Phthalo Blue
Natural
Inorganic No carbon. From the earth. Opaque, low tinting strength, excellent lightfastness Iron, Titanium, Umber
Synthetic Inorganic No carbon. From mostly metallic compounds Opaque, low tinting strength, excellent lightfastness Viridian, Cadmium

Is it true that cadmium colors are the most permanent colors?
No. Although Cadmiums are rated "most permanent" with a Lightfastness Category of I, any color with this rating is of equal permanence.

Is it true that synthetic pigments are less permanent than naturally occurring pigments?
No. Synthetic and naturally occurring pigments can be rated Lightfastness Category I, II or III, depending upon the color. Alizarin Crimson Hue for example, is a synthetic pigment rated Lightfastness I, and is more permanent than the naturally occurring Alizarin Crimson, which is rated Lightfastness III.

Which is more important to the quality of a paint, the pigment or binder?
The pigment determines the color of the paint as well as the permanence of that color.

The binder (acrylic polymer emulsion) determines paint handling characteristics, clarity, flexibility, UV resistance (non-yellowing) and drying and curing times. While both are necessary for high quality paint, it can be argued that it is the binder that is most important, since it is the binder that the artist physically feels while working, and it is the binder that will hold the pigment for future years.

PIGMENTS DETERMINE
Chroma Relative brightness
Opacity Transparent, translucent or opaque
Tinting strength Color strength
Lightfastness How long before color shifts or fades, currently ASTM rated I, II or III
BINDERS DETERMINE
Clarity Clear binders make true color paint films
Drying time How fast paint will dry
Handling Physical qualities - thick, fluid, sticky, smooth, brush drag
Archival Non-yellowing binder won’t yellowing colors over time
Environment Effects of weather on the paint film durability
Blocking Affinity of dry painted surfaces to bond (paintings stacked face to face)
Film hardness Harder film is more durable over time
Flexibility of film Flexible film is more durable over time
Adhesion Types of substrates that paint adheres to, over what time period adhere it

What makes a professional grade paint?
Professional grade paints use high quality pigments and binder. Liquitex Acrylic Artists Color uses no fillers, emulsifiers or additives to increase volume without imparting a positive attribute to the paint. The manufacturing of Liquitex Products include extensive tests to insure consistent quality control, such as freeze/thaw stability, excessive heat, microbiology systems and accelerated aging.

Freeze/thaw stability test: Paint & mediums frozen and thawed seven times.
Excessive heat test: Paint & mediums heated to 325º.
Microbiology systems test: Paint & mediums are exposed to mold spores.
Accelerated age test: Paint & mediums exposed to UV light.

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ACRYLIC vs OIL

Why do oil paintings develop hairline cracks and acrylic paintings do not?
This is directly related to the binders in oil and acrylic paint. Oil paint binder (linseed oil) dries to an inflexible weak film. As weather conditions change and the substrate expands and contracts, this inflexible film can crack. In addition, linseed oil dries very slowly. If lower paint layers contain more oil than paint applied on top, the top layers will tend to dry sooner. This may cause cracks to develop.

Acrylic paint remains flexible, which prevents the paint film from cracking. Acrylic paint binder (acrylic polymer emulsion) dries to a flexible paint film because the molecules interlock. They "move" with the substrate (canvas) during expansion and contraction.

Can you make acrylic paint, look and feel like oil paint?
- Add Liquitex Gloss Gel Medium, Matte Gel Medium, Heavy Gel Medium or Super Heavy Gel to Liquitex Heavy Body Acrylic Color to simulate the density and feel of oil paint. This will make colors more transparent.

- Add Liquitex Modeling Paste alone or in combination with previous gel mediums to Liquitex Heavy Body Acrylic Color to simulate the density and feel of oil paint. Resulting mixture will dry harder and less flexible than paint alone.

- Add 5-10% Liquitex Liquithick to Liquitex Heavy Body Acrylic Color to simulate density and feel of oil paint. Resulting mixture will maintain color opacity. Start by adding 1 part Liquithick to 25 parts paint or medium. Do not exceed a 1:4 proportion as excessive shrinking and cracking may occur. Adding a gel medium increases strength and flexibility. Allow 72 hours curing time

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DRYING

What conditions affect the speed with which acrylic paints dry?
- Substrate More absorbent substrates decrease drying time.
- Thickness of paint application Thin paint films dry faster.
- Environment Dry, warm environments decrease drying time.
- Retardant additives Retard water evaporation, increasing drying time.

How do you increase the "open time" (retard drying) of acrylic paints & mediums?
- Seal substrates with Liquitex Gesso or Liquitex Matte Medium followed by Gesso to prevent absorption of water and paint into the substrate.
- Keep the painting surface and palette moist by spraying a water mist.
- Mix Liquitex Slow-Dri Blending Medium or Slow-Dri Gel Blending Medium into color. Unlimited qunatities will maintain paint film strength and increase transparency of the color.
- Reduce airflow across painting surface.
- Control the use of hot lights
- Humidify studio environment.

How do you speed up the drying of acrylic paint & mediums?
Use a hair dryer.

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STORAGE AND LONGEVITY

What is the shelf life of acrylic paint?
You can expect a 5-7 year shelf life for Liquitex acrylic products, provided the materials are stored properly at room temperature, kept tightly capped and kept free of contaminants. High temperatures, freezing and the use of tap water, dirty brushes and painting tools will all adversely effect the shelf life of the paint.

How do I store acrylic paintings?
The best storage is in painting racks, separated from touching other paintings. The tops of the paintings can be covered to keep out dust. This allows for good ventilation to prevent mold growth. Paintings can also be stacked vertically with acid free cardboard separators. If paintings must be covered, use acid free tissue, followed by plastic film. Do not wrap tightly as to seal in moisture. Do not use bubble wrap as the bubbles can imprint into the canvas. Maintain mild temperature and low humidity levels. High and freezing temperatures can adversely effect the painting and painting/plastic interaction.

How long will acrylic paintings last?
The longevity of acrylic paintings is influenced by paint quality (pigment and binder), pigment lightfastness ratings, application procedures, substrate and the environment. A painting on Belgian Linen for example, in an interior installation, will last longer than an exterior mural on concrete.

What weather conditions adversely affect acrylic paint?
- The resin binder used to make Liquitex Paints and Mediums is hydrophobic (water-resistant) when dry and will not get sticky in hot weather. Many brands of acrylic paint & mediums become soft and sticky in hot weather and bond when stacked face to face. Liquitex Soluvar (Gloss or Matte) as a final varnish eliminates any pressure sensitivity of dry oil or acrylic paint film.
- Liquitex Acrylic Paint and Mediums are oven tested at 350° and freeze-thaw tested 7 times to insure that temperature fluctuations do not affect paint quality and performance.
- All acrylic paints and mediums become brittle in cold weather. Never roll an acrylic painting below 45ºF.

What is the expected life span of murals painted with acrylic paint?
Under normal weather conditions, and proper preparation and application procedure, murals painted with Liquitex Soft Body and/or Heavy Body Acrylic Artist Color rated ASTM Lightfastness Category I, will last a minimum of 100 years in museum lighting with no change in color. The paint film will last well beyond 100 years. Do not use cadmium colors in exterior applications.

How do I prepare a surface for an outdoor mural?
1. Clean surface of any loose and oily material.
2. Seal surface with Liquitex Matte Medium or Matte Gel Medium.
3. Gesso surface with Liquitex Gesso.(2 coats)
4. Paint surface with Liquitex Artists Color.
5. Protect painting with varnish.

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TECHNICAL PROBLEMS

Why is my acrylic paint film powdery, flaky or cracking?
This can be caused by any combination of the following conditions.
- Over thinning paint with water. When thinning acrylic paint with over 50% water, add a painting medium to retain sufficient binding qualities on non absorbent surfaces.
- Inferior quality acrylic paint.
- Mixing too much dry filler (such as sand or sawdust) into the paint.

How do I prevent a finished acrylic painting from becoming sticky in hot weather?
Apply Liquitex Soluvar (Gloss or Matte) Varnish over finished painting.
Apply silicone spray to finished painting.

What is Substrate Induced Discoloration (SID)?
Acrylic mediums (especially when thickly applied) have the ability to draw out impurities from the support (surface) they are painted on. Gesso priming will not prevent. The impurities cause clear gel mediums to take on a yellow to deep brown cast. Pre-washing canvas removes impurities and prevents SID.

How do you know when acrylic paint & mediums are spoiled?
Spoiled paint and mediums may exhibit the following: cottage cheese texture, stringiness, strong odor, coagulated gel texture.

Can I use water to thin thick acrylic to a fluid paint?
You can use just water only for applications on absorbent papers and fabric. In this case, the substrate becomes the binder. For any other application, thinning thick acrylic paint 25% or more with water, prevents it from properly coalescing into a strong, durable, flexible paint film, from trapping the pigment and from properly binding to the substrate.

Keep in mind as well that as water or a water/medium mixture is added to paint, the pigment concentration goes down.

Why do some acrylic colors dry darker?
Acrylic polymer emulsions used in acrylic paint are generally translucent to milky in their wet state. Companies use different qualities and types of polymer emulsion. The milkiness visually tints the color of the paint temporarily. When the paint dries, the polymer emulsion becomes clear and the "true" pigment colors can be seen. Liquitex acrylic paints are manufactured with 100% acrylic polymer emulsion that is translucent in its wet state and completely clear in its dry state, thus minimizing any color shift from wet to dry. When using high ratios of mediums, colos lighten, then return to close to their original color.

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PAINT

Is Liquitex Soft Body Acrylic made from watered down Heavy Body?
Soft Body Acrylic was actually the original Liquitex Acrylic. Medium and Heavy Body Acrylic are separate paints and have their own unique formulations. The colors in each range have an equal pigment load by volume.

Which applications are best for Liquitex Soft Body Acrylic?
All applications except heavy impasto brush of knife painting.

Which paint is best for use in airbrush technique?
Soft Body Acrylic is filtered for this use. It is very easy to thin. The airbrush will not clog from acrylic particles stuck in the head or nozzle.

What’s the advantage of using Soft Body instead of watered down Heavy Body Acrylic for thinner applications?
Thinning Heavy Body to the thickness of Soft Body Acrylic cuts the pigment load in half.

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MEDIUMS

What is a medium?
Mediums contain resin and are added to paint to effect the paint handling characteristics or opacity.

When should I use a medium?
Use a medium when you want to:
-Apply thin or thick glazes.
-Thin paint to a smooth, brush stroke free consistency.
-Thin paint to a watercolor consistency without paint becoming drippy.
-Thin with water while retaining proper binder ratio.

Why are some acrylic mediums milky, some translucent and some clear when wet?
The clarity of a medium is determined by the quality and hardness of the polymer emulsion and by the viscosity (thickness) of the medium. Generally, the harder the polymer emulsion the clearer and more brittle the dried medium. A quality acrylic painting medium has enough flexibility so that it will not crack when used on canvas and when used in thick applications. A medium that is clear when wet may be too brittle when dry. A medium that is milky to white when wet, visually "tints" the wet color, creating a dramatic color shift from the wet to dry state.

Why do some mediums dry yellow?
- An inferior medium was used and did not dry clear.
- The medium was applied thickly and is not completely dry.
- The medium is contaminated or has spoiled.
- The thickness of the medium and impurities in the substrate caused Substrate Induced Discoloration.

Why do some mediums dry hazy?
- Excessive brushwork during application. The dry acrylic particles are distributed into wet medium, creating a visual haze.
- Multiple layers were applied with Matte Medium, or a thick layer of Matte Gel was applied. Matting agents effect how light passes through medium, causing a visual haze.
- Vigorous brushwork over a textured area caused micro sized bubbles to form and dry into the medium.

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VARNISHES

What is an acrylic varnish and why should I use it?
It is a final protective layer, applied when the painting is finished, dried and cured. It is used to establish an even sheen and provide a durable protective finish. It also acts as a UV protectant.

Are there different types of acrylic varnishes?
- Matte and Gloss - Permanent Final Flexible Surface Varnish.
- Matte and Gloss - Removable Final Flexible Surface Varnish.
- Matte and Satin - Rigid Surface Varnish.

What varnish should you use for flexible surfaces?
Liquitex Gloss Varnish and Matte Varnish (Satin Finish) are made to adhere to flexible surfaces.

What varnish should you use for rigid surfaces?
Liquitex High Gloss Varnish or Satin Varnish are specifically made to adhere to rigid surfaces.
Gloss Varnish and Matte Varnish are flexible varnishes that are also suitable for use on rigid surfaces.

What varnish should you use for outdoor surfaces?
Liquitex Gloss Varnish is used as an initial barrier coat over a finished painting.
Liquitex Soluvar (Gloss or Matte) are the final coat varnishes.

How do you protect acrylic paintings from environmental pollution?
Acrylic varnishes alone are porous and environmental pollution can penetrate them and bind with the paint film. Soluvar Removable Varnish prevents pollution and dirt from penetrating into the paint film surface. It is comes off with mineral spirits, taking any dirt with it. Varnish removal will not effect acrylic paint.

Start with a barrier coat of permanent Gloss Medium & Varnish applied to the finished, dry painting. A coat of Soluvar (Matte or Gloss) can then be applied.

Why do I need to use two varnishes when using Soluvar?
Gloss Varnish provides a buffer coat that protects the paint film against abrasion during future Soluvar removal for cleaning. Soluvar provides final UV varnish protection for the work.

How can I remove varnish from my painting?
All Liquitex water emulsion-based varnishes are permanent and therefore NOT removable. Liquitex Soluvar Final Varnish is removable with mineral spirits. The steps to remove this varnish are:
- Remove varnish in clean, well-ventilated area.
- Wear a duel filter respirator (NIOSH approved) and neoprene gloves. Dampen a small piece of lint free, soft, white cloth with mineral spirits (not "odorless") or turpentine – nothing stronger. Do not use ketones or paint removers.
- Work horizontally. Apply mineral spirits generously and allow it to lay on surface for 15-30 minutes. Check periodically. Longer times may be necessary, depending upon age of artwork and strength of mineral spirits. If varnish is not dissolving or dissolving slowly, use a higher strength mineral spirits or turpentine (cover with plastic to slow down evaporation of mineral spirits). Stronger mineral spirits are not labeled as such, but have a stronger odor.
- Rub cloth gently over a small area 1-2 square inches (3-5 cm') until varnish starts to dissolve.
- Using a clean cloth and clean solvent, rub the area again to remove residue. Repeat this procedure for the entire area to be cleaned. If any paint color shows on the cloth, stop immediately and allow the surface to dry.
- Allow painting to dry before reapplying a fresh coat of Soluvar Final Picture Varnish.

How do you avoid brushstrokes in varnish applications?
Liquitex Gloss Varnish (for flexible surfaces) and High Gloss Varnish (for inflexible surfaces): thin up to 25% with Flow-Aid/Water.
Soluvar: thin with up to 25 % turpentine or mineral spirits (not odorless Mineral Spirits).
Application: Paint pad, spray apply or large soft brush.

Why does Matte Soluvar sometimes dry glossy?
The matting agents in the Matte Soluvar settle to the bottom of the container and must be stirred before use (as per label copy). Stir contents for 2-3 minutes with a brush handle or dowel.

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CANVAS

What is the best type of canvas for acrylic paint?
Canvas texture and gesso priming provide the tooth for permanent acrylic paint adhesion.
Belgian Linen: Strong, round uniform fibers give linen a bold texture that can be seen and felt through layers of paint. Natural oils are retained over very long period of time, preserving fabric flexibility. We have had reports of oils in the fibers seeping into acrylic gesso and paint, adversely affecting adhesion.
Cotton: Best for acrylic paints and mediums. Fibers stretch more than linen allowing for tighter mounted canvas. Best grade is "Sea Island". Cotton has flat natural ribbon-like fibers that dry out quicker than linen fibers.
Synthetics: Most synthetic yarns are made of extruded nylon, polypropylene and Dacron filaments. They are processed and primed to provide a receptive surface for water based media. Synthetics are susceptible to sagging in temperatures above 90F.

Can I reuse an acrylic painted canvas?
Yes, it can be painted over with no problem.

Why does my gesso dissolve and come off, when I sand it or paint over it?
The gesso is not completely dry. It is necessary to wait 24-48 hours after the gesso feels dry, before proceeding with any paint application. If you place the back of your hand on the gesso and it feels cool, it is not completely dry.

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Liquitex Products are permanent, non-yellowing, flexible and water-resistant when dry. Keep brushes wet and clean brushes with soap and water. Do not mix with turpentine or oils. To insure desired results, always make a test piece for your particular application and surface.