I've mentioned Peter Wileman's book (along with Malcolm Allsop), Painting Light in Oils, before, and I want to share my experiment with his process for preparing painting panels, with my own modifications.
I like to work on a hard surface - either mounted linen or panels - and I have been looking for a good way to make my own custom sizes and surfaces - especially for the Mountain Series. Initially I experimented with thin hardboard and luan - but neither gave anything close to satisfactory results. So I was interested in the advice Peter Wileman gives in his book and dvd, and gave it a try.
I found 24 x 29 inch sheets of 1/4 inch MDF board for under $7 at a local home improvement store. So - no big deal if the project failed. Following Wileman's recipe, I purchased a can of acrylic (water based) primer/sealer. Pollyfilla - the secret ingredient - is not marketed in the US, and through research I discovered it is similar to dry spackle. But other research, particularly through The Artist's Handbook of Materials and Techniques, by Ralph Mayer, discusses the old method of making gesso first detailed by Cennino Cennini, of slaking plaster of Paris (a process that involves soaking in water) and mixing with rabbit skin glue.
Ok, so as I stood in the home improvement store looking at the two boxes - plaster of Paris and spackle - I opted for the plaster of Paris to use because, after all, this is somewhat of an experiment, and spackle has always seemed gritty and prone to cracking to me.
The primary caution regarding plaster of Paris is that it tends to crack when used on a flexable surface like canvas, but on wood panels the substrate is stable. I used only a scant amount of plaster of Paris - approximately 1 teaspoon to 3 cups of primer, poured into a mixing container - about the consistency of yogurt. Mix thoroughly and brush on to your pre-cut panels.
You can see in the photo above that this mixture is rough on your household paint brush, so work quickly, brushing in multiple directions to give a more textured surface. At least two thin layers, and allow to dry thoroughly between coats. This gave good coverage, but there were a few panels where I used three coats and didn't have any problems.
You could certainly seal your board first using an acrylic product like GAC, but this seems to be overkill according to some resources.
I tried mixing marble dust in the mixture and found that the result was too rough on my brushes and I quickly tired of removing hogs hair from the surface and seeing my rounds demolished within minutes - so no marble dust in subsequent mixtures.
Here are the panels drying - allow ample time and don't stack until you are sure they are dry - trust me, they will stick together and you will have to repaint spots using your mixture.
Wileman also tones the panels as a next step, using acrylic paint. For the Mountain Series I do use either a pink or a blue toned ground, and then add additional texturing before I begin to paint. I have found this surface to be perfect for palette knife work as well as the rubbing and staining that I use - I don't worry about the panels warping as they dry - and my sizes range upward to 12 x 29 and larger without any problems as long as you store them flat and not on a slant. Gravity wins out then, no matter what, unless you add a cradle.
With oil paint, the paint is absorbed and becomes part of each layer, linked chemically, so the purpose of the plaster of Paris is to increase this tooth or absorbency. I dislike some of the oil grounds that I've tried( too slippery) and many times commercial gessos also make it diffricult to lay down the paint - I have actually learned how to use these different qualities to create some of the textures in my work, applying some grounds that are more absorbent than others.
All this points to the benefits in researching and experimenting until you find materials that work the best for what you are trying to do.
Don't settle for what you can find commercially if it isn't working for you.
"I could sure hear you in the book, very upbeat and encouraging...I also loaned your book to my Tucson art teacher and she let another friend of hers read it, too. She’s already doing most of what you suggested...she hates self-promotion like most of us do..." TB, Tuscon, AZ