Panel help?
 

Is there any reason why using an MDF panel well-coated with strong rabbitskin glue, without gesso, would lead to problems, cracking, etc?

According to Micheal Harding, premium paint maker, it is an ideal surface.

Hi Sharon. Thanks for your reply. Since my original post I've had a large gessoed panel, on MDF, crack all over when I applied RSG. The glue pulled the gesso right off the surface.

I always use the same gesso mix, and glue mix. The only variable was the MDF. I'd never use it again. DPI Premium hardboard is the best available in the US, or I use Maple Die Board.

Thanks,

Richard

Micheal said ONLY to use rabbit-skin glue, there was no need to use gesso on the MDF board.

Did the board crack using just the rabbit-skin glue on the MDF alone?

Also, I do not know what you mean by STRONG rabbit-skin glue as opposed to regular rabbit-skin-glue. He said to use two coats and did not mention anything about STRONG rabbit-skin glue.

Thanks for the tip on the quality MDF board.

I have used it with Acrylic Gesso for Pastel, a Golden product and the MDF has performed just fine, no cracking etc..

Sure, not using gesso would eliminate the chance of it cracking. However, there's the good chance that unprimed MDF will discolor or fade, soo it should probably be covered completely.

I have a piece of ABS I am trying. So far, I like it.

The MDF seems more stable than all of the hardboard I tried, with the exception of the DPI Premium hardboard.

Micheal Harding is the one to query on this. I talked to him about 2 hours (his nickle) regarding materials. He is a very well respected and believe you me, fussy paint maker.

He felt that the MOST stable surface for painting was the MDF board coated with 2 coats of rabbit-skin-glue-no gesso needed. He felt that this was a far superior surface to any of the panels made today and far better than painting on canvas. It is simple and cheap.

Why do you think it would discolor? It hasn't for me. Sometimes the simplest thing CAN be the best. I cannot imagine putting rabbit-skin glue OVER gesso.

As to ABS, I use plexiglas for my pastel box covers. My plastics man has ABS sheets. He told me he would not use them for painting, because they absorb moisture (not good for paint surfaces) warp and are heavy. He has stacks of ABS and can't keep them from warping. Also you have the problem of outgassing with a product like ABS, which means future embrittlement and yellowing. Just ask my husband, he has a doctorate from Brown University in materials and electrical engineering. Also there is a thread here somewhere about the head conservationist at the National Gallery in Washington, who has warned against substrates made of plastic resins.

Sharon, I did addres most of these MDF questions to Michael, but got no response beyond I'll look into it.

Michael Skalka, at the NGA, told me to stay away from MDF, esp. because unprimed wood and wood products are not lightfast.

I've got lots of concerns about the ABS, but someone sent me a sheet and asked me to compare it to the panels I am making. So far I've only gotten a midvalue gray down. It's taking a long time to dry. I saw photos taken by Richard Bingham, showing severe warping due to cold. This was with mounting on plywood.

But Rob Howard has recently spoken highly of the ABS, so I am keeping my mind as open as possible.

Oh, RSG over gesso is a way to keep graphite from creeping through.

Why do you care if it is lightfast IF you are going to cover it with paint? And you are actually sealing it with rabbit-skin glue?

If you want a stained or translucent look you could just cover it with lead white and THEN put a wash over it.

At the time I asked the question I wanted to know if I could use the light brown color as a base. THat's how lightfastness came up. MDF seems more structurally stable than hardboard, except for the DPI I mentioned, so eliminating the gesso and covering it with paint should work. I have something I prefer much more, copper.