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Friday, August 9, 2013

Painting on Panel: Acrylic Priming


We have reviewed how to size and seal wood and how to prime it with oil primer.  Some of you may prefer to use an acrylic primer, or an acrylic dispersion ground for you work.  Our best recommendations for the process are below.  

Golden® brand acrylic gesso is our first recommendation.  However, these instructions are virtually interchangeable with a number of other brands if there’s one you like better or have more readily available. Gesso is a flexible liquid ground that seals, protects, and gives "tooth" to wood panels, which promotes good paint adhesion. It comes ready-to-use, but can be mixed with water for thinner applications. Golden® Gesso is available in Black or White, and can be mixed with Golden® Acrylics to produce a range of colored grounds. Gesso can be applied with a brush, roller, putty knife, Catalyst™ wedge #W-06 or sprayed on. Dilution of the Gesso is only necessary for spray application, but may be desired for brush or roller applications as well. When diluting with water, use a maximum dilution of 25%. Any mixture within this range offers little risk of cracking or other adverse effects.


Step 1 – Size and seal the wood
A size is a thin solution (often a weak glue) that is brushed directly onto a support. Sizing or sealing is recommended to protect Ampersand’s uncoated panels from support-induced discoloration when using acrylic gesso. If wood is not sized or sealed properly before applying the gesso, yellowing can occur because water [a solvent] can cause acids, occurring naturally in wood, to migrate to the surface. In fact, it is extremely important to properly seal any and all un-primed wood substrates to prevent support-induced discoloration that can cause your paint film to yellow over time. Hardbord™ is manufactured using Aspen fibers, a wood with a very low acid content, but still needs to be sized and sealed. The Natural Wood Panel™ and Unprimed Basswood panels are made with a thick basswood plywood top that has been sanded ultra-smooth. They are both seamless and knot-free and provide a perfectly smooth and uniform painting finish. When you size and gesso the basswood surface, you won’t experience the raised wood grain fibers that can happen with some other rougher types of plywood; the surface stays nice and smooth. The basswood panels have solid wood cradles and braces that may be more susceptible to moisture and environmental changes than the birch plywood cradles we use on the Hardbord™. Therefore, Ampersand recommends that you prime both the front and back of the Basswood top to ensure long-term stability of the panel.

The best products we have found to seal wood are Golden®GAC100 [2 coats]  and Gamblin® PVA Size [4 coats].

Apply Golden® GAC100 directly to the basswood or hardboard surface with a 2" paintbrush or putty knife. Apply to the front and back if applicable. Allow the GAC100 to dry completely and follow with an additional coat. Do not sand between layers. Before applying oil primer or the painting ground, allow the GAC100 to dry for 1-3 days so that the sealer can coalesce into a uniform film for maximum protection. If you’re using Gamblin® PVA Size, use 4 coats and follow the same application instructions as for the GAC100.

Step 2 – Protect and prepare the cradle
Hardbord™ is available in either a flat 1/8" panel, with a 3/4" cradle, or with the 2" DEEP cradle. The Natural Wood and Unprimed Basswood panels are available in both a 7/8" cradle and 1.5" cradle profile. You have the choice of painting all the way around the cradle or leaving the natural wood showing for framing purposes. Be sure to size and seal the bare wood if you want to paint completely around the edges of the cradle. Or, to protect the wood from paint and gesso, cover the sides of the panel with painter’s tape up to the edge of the surface. Do not remove the tape until the painting is finished. Painter’s tape does not leave a sticky residue like many household masking tapes that can be difficult to remove, and will leave a pristine surface underneath when the painting is complete. For instructions on different ways to prepare your cradles for presentation, consult this article: http://www.ampersandart.com/featuredartist/featured-artist-pramuk1.html

Step 3 – Apply the Acrylic Gesso
Thin the gesso with up to 25% water for the first coat so that it will flow more evenly on the [sized] panel. Use a 2"-3" brush for the first coat and a foam roller for subsequent coats. Begin by working the gesso back and forth with the brush in one direction and then in a cross direction with a little pressure so that the gesso penetrates the panel better. Apply gesso to the side edges of the panel and the plywood cradle if applicable. Don’t forget to seal the cradle with Golden® GAC100 first if you are going to gesso the edges for painting. The basswood panels have solid wood cradles and braces that may be more susceptible to moisture and environmental changes than the birch plywood cradles we use on the Hardbord™. Therefore, Ampersand recommends that you gesso both the front and back of the basswood top to ensure long-term stability of the panel. Allow the front of the basswood to dry completely, then, gesso the reverse side.

Step 4 – To Finish
After the first coat of gesso is dry, smooth out any rough spots with light grade sandpaper. Apply a second coat of gesso with the foam roller (or brush). Allow it to dry and then sand again. For best results, apply a minimum of 2 coats of gesso and sand in-between. Subsequent layers of gesso will produce an even smoother painting surface. For spray-application, you may have to apply more than 2 coats to achieve a film similar to a brush application. For basswood panels, follow the same instructions, but also prime the back. For each additional coat to the panel face, apply the same number of applications to the panel back.

The fall sale is on!  Hardbord, Gessobord, Claybord, Encausticbord and all Artist Panels are all on sale, 20% to 60% off at a dealer near you!

All things Ampersand, 
Karyn Meyer-Berthel 
Artist & Social Media Specialist 
Ampersand Art Supply 

Click here to explore the full selection of Ampersand panels and tools.

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