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-   -   Warping mdf-panel (http://www.eggtempera.com/forum/showthread.php?t=32)

Camilla 02-01-04 12:42 PM

Warping mdf-panel
 
All new to temperapainting I thought I might as well just start out with a 80x100 cm panel ...
To prevent warping I screwed stretcher bars onto the panel (which is 12 mm thick) and put a few layers of gesso on the back, but not as many as on the front. But it didn't help - it warps about 1 cm.
Is there a way to rescue this, for instance by applying more gesso coats to the back, or is it a lost cause? (Damn, that panel took ages to prepare!)

Camilla

PhilS 02-01-04 01:18 PM

Hi Camilla,
I have corrected slight warping by adding gesso to the back. I doubt this would work with severe warping, though. My advice is, in the future always apply the same number of coats of gesso to both sides (the panel will temporarily warp toward the last side gessoed, but will flatten out when dry). Gessoing this way, I have found that I don't need to brace my panels - and some of my panels are fairly large.
Hang in there!
Phil

Camilla 03-01-04 03:14 PM

Thanks. I'll try a rescue mission with more gesso on the back to see if that helps. But if several layers of gesso won't bring my panel back into shape, do you think that such a crude procedure as splashing an awful lot of water on the back can make my panel unwarp (or perhaps counterwarp)? Or will it most likely ruin everything completely?

Camilla

David McKay 04-01-04 02:04 AM

Hi Camilla:

I am not sure what you mean when you say that your panel has warped one cm. If you mean that is the amount your panel would lift up in the middle if it were layed down on a table, then that dosen't sound like very much to me at all. Although gesso is brittle, surely that amount of warpage could be easily corrected when the panel is framed, given the rather large overall size. Maybe I have misunderstood?? :-)

David

Camilla 04-01-04 02:01 PM

When I lean the 100 cm side against the edge of a table (which I assume is pretty straight) the corners of the panel touch the table edge and I get a 1 cm gap between the middle of my panel and the table edge. That is, the corners lift up, when I lay it on a table face up.
I wanted to avoid framing because it would make the painting even heavier (already it weighs about 10 kg, I think) and because it will be quite expensive. However, I don't see how framing would solve my problem. I rather thought the warping would make framing impossible, since mdf is a ridgid support you cant twist like a canvas on stretcher bars.

Camilla

jason_maranto 04-01-04 02:25 PM

ridgid is a relative concept.


Jason.

realgesso 04-01-04 06:13 PM

Quote:

do you think that such a crude procedure as splashing an awful lot of water on the back can make my panel unwarp (or perhaps counterwarp)? Or will it most likely ruin everything completely?
Camilla, Don't put water on MDF, it will cause it to swell in a most unpleasant manner. Gessoing both sides prior to painting is one technique that works, another is to use a thinner support. I'd recommend using some kind of tempered hardboard, it's stronger and less absobant than MDF. Using a thinner support such as 1/8" or 1/4" hardboard is much easier to pull back into shape when framing...Max

RobM 04-01-04 07:54 PM

Camilla,
I rescued an MDF panel which had warped slightly more than yours.
I applied more gesso to the reverse then placed the panel on two pieces of say 10 to 20mm strips of wood positioned at the far ends of the panel and then place a weight in the centre of the panel. This would then provide a counter forced warping. Leave the panel to dry thoroughly and then remove the weight. It worked for me.
Rob

Camilla 04-01-04 09:58 PM

This sounds like a good idea. I'll try that. How much weight do you think, I should use? Would a couple of kilos be sufficient?

Camilla

David McKay 05-01-04 03:07 AM

Hi again Camilla:

I use one quarter inch hardboard without any stretcher bars or cribbing. The panel almost always warps slightly so that the front, the side I paint on, forms a slightly concave shape. This is pretty much corrected when I frame it because all four sides are straightened out by the frame. I understand your dilemma however, if you don't want to frame your painting. I have also used weights as Rob has suggested. You would have to turn your panel face down on a table and while placing something under all four corners of the panel put a weight in the middle of the reverse side. I think you would have to put enough weight on it to actually cause the panel to temporarily bend in the other direction. If it is possible to take your stretcher bars off while you do this it might make the proceedure a lot easier. It may also take several days to correct the warping. Sorry for your problems. David :-(


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