Tempered or Untempered Masonite
 

I have tons of tempered masonite laying around, but I heard somewhere that I should use untempered. Looking in past posts I have seen that Chris Saper uses tempered. Does anyone know which should be used or does it matter?

Joseph,

Tempered Masonite is a very good choice for a substrate. I have had excellent results using hardboard. I used to use the untempered masonite but endured too much damage to the edges because it is relatively soft. The fact that it is cured has never presented a problem to adhesion. I scuff the surface with 320 grit sandpaper to create a mechanical tooth and wash it with alcohol to remove any residues and then apply a diluted solution of rabbitskin glue. I then apply about 6 coats of gesso made with bunny glue and whiting/titanium oxide, make a X on the back and I am ready to go. I know there has been alot of debate about the curing process with tempered and the leeching of oils to the surface. Today's products are superior from years ago, especially a hard board product called DURON, an incredibly durable surface. Below is a pic of this product taking a 4 x 8 x 3/16 panel cut into portrait sizes of 14 x 18....L

I agree with Leopoldo . . .
 

I'm new to this forum, but glad that I found something right away that I can comment on! I am an aviation artist, new to portraiture, but all of my acrylic works have been on 1/4" Tempered Masonite which I bought at Home Depot.

Like Leopoldo, I sand the surface [I use 220 grit, by hand], then lightly wash the surface with water [not too much or the board WILL warp]. I typically put on 2-3 coats of Acrylic Gesso, sanding between coats. Let the acrylic gesso dry at least 24 hours between sandings.

My pieces, while relatively heavy, are sturdy and show no signs of adverse affects to the paint. I'll let others comment about Tempered Masonite vis-a-vis oil paints.

Glad to be here!
Wade