Straightening a resin cast body with a dehydrator

[BigTallDad]

I recently picked up a '92 Olds Supreme resin cast and, after setting it on a flat surface, noticed that there is about a 1/4" twist in the body, front-to-back.

If I take a very flat board, attach the body with non-marking clamps (with perhaps a few shims to "over correct" the twist) then set that assembly in a dehydrator, will the heat cause problems in areas that are not under stress? For example, would I get a roof melt-down even though there is no pressure on the roof?

[MrObsessive]

Ray, I tried the dehydrator method years ago when the '59 Buick I was working on had a slight warp to its roof. If it were me, I'd try this in five minute intervals. I'm not so sure about the clamping method-------I would try and twist it on my own without the stress of the clamps.

A better idea might be to put the body in hot (not boiling) water, and try it that way. You wouldn't run the risk of warping the roof, and you'd have a bit better control. One caveat with resin when you try to change any warping, is to not to wash the body in warm/hot water again for cleaning. Resin DOES have a memory and it'll want to go back to its original shape if you reheat the body later.

EDIT: You might want to keep a bowl or something of cold water right next to your hot water. As soon as you get the body straightened after you heat it, immediately put it in hot water to "lock" it in place.

Hope this helps! 

Edited April 17, 2017 by MrObsessive

[Art Anderson]

Bear in mind that polyurethane resin softens at a much lower temperature than does polystyrene, and it's not a gradual transition from hard to soft:   That said, resin bodies, even if perfectly straight out of the mold, can (if put under stress--such as packing in a box under stress) can warp over time as well.

my advice (speaking as a former resin caster with experience gained from thousands of castings) would be to be VERY careful about using heat for that very reason.  I've had success in straightening a warped (as in twisted) resin body shell by strapping it, with tape, firmly to a known flat surfaace (in my case, I have several pieces of thick tempered plate glass for building surfaces), and have done this.  Key here is patience--the warpage won't come out overnight--it might take several days to accomplish.

As Bill Geary mentioned, resin does have a bit of a memory--if the body shell originally came out of the mold, then it should straighten and remain so, but if the master got "twisted" when it was being "laid up" for mold making, then the warp or "twist" may very well creep back in, unless the body is held in its straight configuration promptly during final assembly.

Art

 

Edited April 20, 2017 by Art Anderson

[AJM]

Art- just searched for a post on warped bodies. I have a resin body that was warped, I put it in warm water and straightened it out;.then put the body on the chassi and it's been in that position for months and the body still looks good. Just took the body off the chassi to begin the body work/cleanup and noticed that the body began to deform again -- will soaking the body at a low temp, have the effect of curing the body? I just put the body in the refrigerator to soak for a while.

Will putting a primer coat on the body do anything to keep the body rigid -- I'm concerned that if I paint it, that over time the body will form cracks, if the resin is still soft. Need help, any advice,

thx

Al

 

[AJM]

Does anyone have any advice on the above response. Thx, appreciate the help , in advance .

Al