Aug 5, 2009

Preparing different surfaces with Liquitex Gesso


Artists have used wooden panels for centuries. The ones that were properly cared for still survive today. If those early artists had access to masonite they would have preferred it to wood. Masonite is a wonderful surface to paint on, and much cheaper than canvas. The only disadvantage is that is does not have the "spring-back" feel of the canvas.
I found that I could go to my local hardware store( Home Depot or Lowes) and buy a large panel, my hubby could cut it or they would cut it at the store. This is so inexpensive. I could get many paintings our of one large panel!
The first thing you want to do is to make sure the masonite is untempered, never use tempered masonite. Untempered masonite is used because its a non-oil surface.
Tempered masonite will not hold gesso or paint very well, in time the painting will flake off.
Cut the masonite to the desired size and sand the edges to get rid of the burs.
Apply a coat of Gesso to both sides to prevent moisture entering the panel causing deterioration and warping.
I find that Liquitex Gesso is the very best to use, do not thin with water, use it straight out of the bottle.
Use a nylon brush for the back and a foam brush for the front, when coating the front brush the gesso on in one direction for the first coat, let dry and then apply the second coat brushing in the opposite direction.
Apply at least 3 coats on the front of the panel. When the gesso is dry, apply water to the front with a sponge, hold over a sink , now with a #280 or #320 waterproof sandpaper, sand in a circular motion on the wet surface until the entire surface is smooth. Rinse with the wet sponge, wring it out and wipe the panel to remove the excess water.
When dry feel it to make sure it is smooth, if not repeat above process.
Applying the "Tooth" coat.
If you tried to paint on the panel now it would be slick as glass, you would slip and slide all over the place. You need a bit of "tooth" or "texture" to prevent this. Follow the instructions carefully in applying the "tooth" coat.
Mix 3 parts of water to two parts of Liquitex "Modeling Paste" using a level measuring spoon. Please measure very carefully. Mix completely to remove all lumps. Modeling paste is an acrylic and marble dust solution. The marble dust gives a fine sandpaper-like finish to the surface. It is just wonderful to paint on!
Apply a thin, even coat of this with a sponge brush over the prepared panel. When the panel is covered, use another dry sponge brush and crisscross very lightly over the panel until the water is almost gone, the water lines will not be visible now. Dry spots will start to show as the moisture is removed.
Let this dry completely.
NOTE: The "tooth" coat is very venerable to damage , be careful not to rub it or scratch it. If you do, that area may show through after the painting is finished. I would do a few at a time and wrap them in tissue paper when the were completely dried to protect them.
I know this sounds like a lot of work, but if you get your panel all cut and sanded and gesso it all at the same time you will have many wonderful surfaces ready to paint on. Be sure to make your cutting the sizes of the frames if you are planning on framing your work. I encourage you to try this, once you do I am betting that you like so many of my students will find a new "favorite' surface to paint on!!
Surface Preparation: Rigid Surfaces
Rigid surfaces provide smooth or textured surfaces for artists who paint dimensionally and attach objects to rigid surfaces. Most boards can be used as supports to which canvas, paper or other material can be glued. Use Liquitex® Matte Gel Medium to adhere canvas to board.
The following surface preparation procedures for painting on board serve as general guidelines for most acrylic paint applications. Surfaces should be tested for proper adhesion of paint and compatibility of material for adhesion. See Adhesion Test below.
ACETATE
Acetate is a transparent, somewhat brittle plastic available in varying thickness and surface textures.
Matte-surface acetate, textured acetate and wet-media acetate (also called "prepared acetate") are suitable for acrylic paints, mediums and gesso.
Smooth acetate is not recommended, as the surface is smooth and slick. Paint will not adhere.
Wet-media acetate is a clear, smooth acetate that is chemically treated so that acrylic paint, mediums and gesso will not repel away from its surface.
CANVAS PANEL BOARDS
Prepared canvas panel boards are commercially available in a wide variety of sizes and a limited number of surface textures.
They are usually made of cotton canvas wrapped and
glued onto heavy cardboard.
Not recommended for permanent work, as they may warp and the glues and papers used in their manufacture may not be permanent.
FIBERGLASS
Fiberglass can be painted with acrylics or oils if the surface is prepared properly.
1. Sand or sandblast the surface. Remove residual dust.
2. Coat with an industrial primer-sealer meant for use with water-based media.
3. After the primer is completely dry, test for proper adhesion (see Adhesion Test).
Spray or brush on Liquitex Gesso or Liquitex Clear Gesso. Let dry overnight. Again test for proper adhesion.
FOAMBOARD
Provides a smooth, inert, stable, uniform surface, but they are very susceptible to warping and impact damage.
1. Lightly sand the surface with very fine sandpaper and apply one or two coats of gesso. Sand between coats. Let dry overnight.
MASONRY AND CONCRETE
There must be no waterproofing, cement paint or silicones on surface. These materials are often used during construction and can adversely effect the longevity of the paint.
1. Masonry and concrete must be thoroughly dry and cured. This may take 8-12 weeks after set-up. All moisture must be gone or acrylic paint adhesion will not be permanent.
2. Liquitex Acrylics can be applied directly to a masonry wall, but it is best to first trowel on a layer of Liquitex Matte Gel Medium. This provides an excellent ground for the paint, seals the rough texture of the wall and reduces the amount of paint needed to paint surface.
3. Let Matte Gel Medium to fully dry, then apply one or preferably two coats of gesso. Let dry overnight before painting.
4. If the back of the cement wall is subject to moisture it may cause the paint film to separate from the wall.
METAL AND GLASS
Sand with 400-grit paper or sandblast for proper paint film adhesion.
Aluminum should be etched with a 5% lye solution for 4 to 5 minutes.
Glass can be acid-etched or sand blasted.
1. Wipe surface with a degreasing solution and coated with an industrial primer meant for use with water-based media.
2. After the primer is completely dry, test for proper adhesion (see Adhesion Test).
3. Spray or brush apply Liquitex Gesso or Liquitex Clear Gesso Let dry 3 days and test for adhesion.
MURALS
Murals cover a variety of techniques, including fresco, encaustic, mosaic, stained glass and photography. The
type of mural technique most used is either painting on canvas, which is then attached to a wall or painting directly on the surface of the wall itself.
When painting directly on any wall, there must be no grease, wax or oil on the surface. It needs to be structurally sound and free of loose particles. It must not be subject to dusting. Back of the wall must not be subject to extreme moisture conditions.
Refer to Part II Applications & Techniques: Murals
MYLAR
Mylar is a film that has all the properties and uses of acetate with additional flexibility and strength. Much higher in price than acetate, it does not stretch, crack or yellow and is also available with a photosensitive surface for the reproduction of line drawings.
Like acetate, Mylar is available in a wet-media form that needs no surface preparation.
PLASTERBOARD
Use plasterboard walls only if not previously painted with oil or alkyd paint.
1. Prepare the surface by sealing it first with a barrier varnish such as Soluvar® or an industrial primer/sealer like AqualockTM, made for use with water base paints.
2. When sealer is completely dry, apply two coats of gesso with a brush, spray or paint pad.
PLASTIC PANELS (PLEXIGLASTM)
Depending upon the type of plastic, acrylic paint can be applied directly to the surface. Some plastics will repel acrylic paint, some are very smooth and the acrylic paint will easily scratch off and some have a slight tooth and provide the best surface for paint adhesion. The plastic must be chemically inert so that it will not react with the paint film over time.
1. For the most permanent acrylic paint application, sand the entire panel or sand only those areas that will be painted to preserve the transparent nature of the product.
2. After sanding, coat with a layer of Liquitex Matte Medium or Matte Gel Medium and one or two coats of Liquitex Gesso or Liquitex Clear Gesso.
Plexiglas is an acrylic sheet material manufactured in a variety of widths. When sanded, it will provide adequate surface tooth for acrylic paint. Both sides of the sheet can be painted to yield dimensional qualities.
When working with transparent colors use Liquitex Gloss Medium & Varnish, Glazing Medium, or Gel Medium to maintain clarity.
PLYWOOD
MDO Boards are varieties of plywood that are bonded with paper on one or both sides, available from sign making supply houses. They offer a very smooth surface quality that is hard to achieve with standard plywood.
Negative aspects- weight.
Good exterior grade plywood or birch plywood provides an excellent painting support.
Plywood is available in 1/8" thickness (called "door skin") of mahogany, birch, maple and oak. The harder woods, such as birch, maple and oak will require less gesso to seal and provide a smooth surface. Plywood sheets may be adhered to wooden stretcher bars for added strength and to prevent warping. Glue and nail plywood to stretcher bars every 3-4".
All forms of plywood will require between 2-5 coats of gesso.
UNUSUAL SURFACES
Unusual surfaces should be tested for compatibility with the acrylic paint. Certain paint and surface combinations may react with one another, either immediately or over time.
The type of surface and ground used with acrylic paint has a large effect on how the paint handles.

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