Criteria for using Masonite as a support surface for WSO

Chantel.

Could you explain some of your criteria for the masonite board you use? I have a painting I want to do that will be 24 x 40" and I'm not sure exactly what I should look for in masonite, especially the thickness.

Judy

Hi Judy,

That's a pretty big piece of masonite. I generally do not go over 16 x 20 because a) it gets too heavy and b) it tends to warp in bigger sizes. The bigger the size, the thicker you have to go (which adds to the weight!). I used streched canvas for anything bigger than a 16 x 20.

Should you decide to try it though, here are a few tips:

- get untempered masonite (this means untreated - the other stuff is treated with chemicals that may bleed into the paint)

- I use 1/16th to 1/8th inch thick for my panels ranging from 16 x 20 to 5 x 7. You may need to use quarter inch masonite for a larger piece. I buy a 4 x 8 sheet from the hardware store and have them cut it into mostly 11 x 14 and 8 x 10 because those are my favorite plein air sizes. It's quite cheap, but make sure you tell them you need those cuts to be precise! Once, they made a mess of my sheet, cuts were crooked, over a millimetre too wide - doesn't sound like a lot, but try putting it into a standard size frame! I ended up re-cutting a lot of panels with an exacto knife. But I went back and ordered more, specifying what I was using them for, and this time they did it perfectly. Must have been a different guy cutting!

- to avoid warping, as well as moisture seeping in and causing your panel to swell right up, you may want to seal the panel. I've done this before, using shellac. You have to get it on both sides, and on the edges. This is a pain to do, and I don't bother with smaller panels as they usually don't warp much, but with a large panel, I'd recommend it. After the shellac, I Gesso the panel (two coats) mixing in a little pumice for texture. Once dry, I sand it down a bit to get rid of ridges. By brushing the gesso on in a perpendicular pattern (horizontally for the first coat, vertically for the second), you get a criss-cross pattern similar to canvas. For smaller panels, I just Gesso them.

Thanks Chantel for such a thorough explanation. I'm still not sure of what I'll use, but this will all come in handy to know.

Judy

I his discussion about using wood as a support surface, Dave Clemmons explained about shellac which might be useful information here also.

Quote :

For sizing wood, I prefer shellac. It needs to be of good quality and dewaxed. The main advantage it has over other
options is there's no water used and it dries quickly. If you don't want to bother with that and can't get RSG (which would be my 2nd choice) I'd suggest PVA (polyvinyl acetate) Gamblin sells this. Golden sells a medium called GAC 100 that can also work well. If you wanted to paint on that directly instead of priming, PVA can be rather slick
under oils and cause adhesion problems.

As I may have mentioned here before, wood can cause staining problems if the size layer is not
sufficient. I need at least 2 coats of shellac, 2-3 coats of RSG, and 3-4 for PVA. For water-based applications you need to let the water evaporate completely and that can take several days.
_______________________________________________
David Clemons
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For a complete discussion regarding wood support (where this quote was taken from) go to

https://watersolubleoils.forumotion.com/water-soluble-oils-f5/what-type-of-wood-makes-a-good-support-t155.htm

A panel that large will need back bracing to keep it straight. I would recommend 1/4" hardboard with cross bracing at least every square foot. Don't glue it all the way across the brace, but instead use about 1" strip of adhesive every 4-6". Other options are to glue it to 1/2-3/4" plywood or a honeycomb aluminum support, which of course adds to the weight and cost. If you do that then thinner hardboard would be fine.

For me, I want to be reasonably certain the manufacturer has made the hardboard from quality materials. Otherwise, I would only use it as a support for canvas or paper instead of painting on it directly.

Thanks David,

I'm still debating on what to do. I have a red cedar frame I all ready made for someone which is 24 x 40". After I got it all done, they decided to go with a black frame instead so I want to do something with it, since I love the way red cedar looks with all of my paintings.

Judy