Oil painters must seal wood to stop any acidic oil in the paint from penetrating into the wood support, which can cause wood fibers to rot. While acrylic painters do not have this same issue, and many of us skip this step, some artists still consider sealing an important step for using acrylic paint on wood to eliminate Support Induced Discoloration (SID). SID is a phenomenon that occurs uniquely with acrylic paints. Wood supports naturally contain impurities that can cause an amber yellow discoloration to any light colored acrylic layer that is applied unless the wood is sealed properly. More about SID on Golden’s website https://bit.ly/2E76okg Sealing (sometimes called sizing) may also reduce chances for the wood to warp due to shifts in humidity.

Sealers are often confused with primers. A sealer protects the underlying layer or material. It usually needs to be glossy (or non-absorbent) to properly protect the surface by creating a barrier. We recommend gloss medium as a sealer for your panels.

Generally, a primer refers to a coating that strengthens adhesion and prepares the surface for the acceptance of paint. Gesso is a primer and not a sealer. Gesso, when applied, has a satin or matte finish, is absorbent in nature, and therefore will not adequately seal the wood unless multiple applications are used – and this still may not fully seal the wood.

A general rule is to apply at least two coats of sealer directly onto the raw wood to protect the wood. When dry, apply primer (gesso) to enhance adhesion, return tooth to the surface, and whiten the surface for optimizing paint colors applied over it.

Instructions to Prepare Your Panel

  1. Clean off any dust or debris from all faces of the panel including the cradled sides, first using a vacuum or air pressure if very dusty, then wiping clean with a microfiber cloth (or other lint free cloth) slightly dampened (with water).
  2. Lay the panel flat on a table, propping it up several inches on all four corners with jars, wood props, etc., to allow for wiping away any drips, and for ease of application.
  3. Apply gloss medium, Golden’s GAC 100, or Gamblin’s PVA Size over all exposed wood surfaces. GAC100 is thin and doesn’t create brushstrokes like the Gloss Medium. Both work fine.  Do not sand between layers of the sealer. 

Note: Let one surface dry fully before flipping over to seal the reverse side. Drying times can vary. When dry to the touch with no tack, it can be flipped over without sticking to the table or other props.