Hardboard panels preparation

 

Hi David:
 Is it sound, from an archival point of view, to seal a hard wood panel or masonite panel with acrylic gesso, if you intend to paint in acrylics?  I'm wondering about water molecules getting into the board.
Thanks,
Angela

Hi Angela,

Hardboard is an excellent, permanent, rigid support for oil, acrylic, tempera, or mixed media work.  Yes it is sound from an archival point of view to use acrylic gesso as a ground.  But there is more.  You do need to first seal the board with a size so that the water from the gesso does not get into the wood.  The water will often come back through the gesso later bringing with it acidic impurities from the wood.  These will change the color of the gesso/paint (brownish/yellowish).  This phenomena is known as SIDS (Support Induced Discoloration).  See my article on SIDS in the Nov/Dec 03 FCA Magazine. 

You can use a thin coat of pure resin Shellac to seal or 'size' the board first.  Pure White Shellac diluted 3 parts Methyl Alcohol (Hydrate) to one part Shellac is a good formula.  You can actually purchase both the Shellac and the Methyl Hydrate at most hardware stores.  You can also use the Golden GAC 100 as an alternative size before applying the gesso.  Although the GAC 100 is a water based medium, it is quite impermeable when dry. 

Here is an excerpt from an instructional paper I wrote that describes how to prepare a painting panel:

How to Make a Painting Panel

Supplies you will need: 
Untempered hardboard cut to size, White Shellac or Golden GAC 100, Methyl Hydrate, a wide brush, no. 60 or 80 sandpaper, Acrylic Gesso.

 

1.  Buy Untempered Hardboard.  You can get smooth on one side or smooth on both sides.  Hardboard comes in two thicknesses, 1/8” and ¼”.  For paintings up to about 16x20 I use the thinner 1/8”, and for sizes up to 20x30 I use ¼”.  It comes in 4x8’ sheets and most hardware stores will cut it for you for a fee. 

2.  Sand the smooth surface before sizing.  No.60 or 80 sandpaper is good.

3.  Size both sides of the panel with a mixture of 3 parts Methyl Hydrate to 1 part White Shellac.  Apply the shellac in a thin layer in one stroke of the brush or roller.  If you apply too much size the surface will become too shinny and smooth and the gesso will not adhere well to it, then you will have to sand it again.  If you are using the GAC 100, put 1 coat on the back and 2-3 on the front, you can thin it with a bit of water (up to 20%) to help it spread if you need to. 

4.   Apply the Acrylic Polymer Gesso on each side of the panel, one coat on the back and at least two on the front.  If you want a very smooth finish you can sand with fine sand paper, 200 grit or higher, between each coat after it has dried.  You can use an inexpensive gesso on the back since its only purpose there is to keep the panel from warping, and a premium quality gesso on the front.  You will find the best gesso will have more covering power and better adhesive strength.