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Resin part warpage???


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#1 jeffs396

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Posted 03 July 2010 - 09:16 AM

I've had an issue lately with resin parts warping while drying in the sun...here in NE Ohio lately, the temps have been nice (mid 70s) with low humidity, perfect for priming & painting in paint booth #1 (outside).

Just wondering if anyone else experiences this with their resin stuff, these parts are the white resin that look like styrene, not the amber-colored resin.

Been using dark-colored primers for one thing which absorbs the heat more, but at these low temps and only sitting in the sun for about 15 minutes, I wouldn't think it would be an issue...

Is this resin more prone to warpage than the yellowish stuff?

#2 Lyle Willits

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Posted 04 July 2010 - 02:49 AM

I've had an issue lately with resin parts warping while drying in the sun...here in NE Ohio lately, the temps have been nice (mid 70s) with low humidity, perfect for priming & painting in paint booth #1 (outside).

Just wondering if anyone else experiences this with their resin stuff, these parts are the white resin that look like styrene, not the amber-colored resin.

Been using dark-colored primers for one thing which absorbs the heat more, but at these low temps and only sitting in the sun for about 15 minutes, I wouldn't think it would be an issue...

Is this resin more prone to warpage than the yellowish stuff?


Drying in the sun???? Are you serious?
I think you've answered your own question. Primer the part / body and bring it in the house!

Edited by Lyle Willits, 04 July 2010 - 02:49 AM.


#3 jeffs396

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Posted 04 July 2010 - 08:42 AM

Sorry professor, with temps/sun barely warm enough to melt ice cream, I wouldn't think it would be an issue...been doing this with styrene for 30+ years & never had a problem.

I'm going to go running with scissors now...

#4 Art Anderson

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Posted 04 July 2010 - 01:10 PM

I've had an issue lately with resin parts warping while drying in the sun...here in NE Ohio lately, the temps have been nice (mid 70s) with low humidity, perfect for priming & painting in paint booth #1 (outside).

Just wondering if anyone else experiences this with their resin stuff, these parts are the white resin that look like styrene, not the amber-colored resin.

Been using dark-colored primers for one thing which absorbs the heat more, but at these low temps and only sitting in the sun for about 15 minutes, I wouldn't think it would be an issue...

Is this resin more prone to warpage than the yellowish stuff?



You may think low temperatures, but in strong sunlight, in the summer, there can be enough heat buildup even in a styrene part to soften it, cause it to warp, and polyurethane resin is even more susceptible to heat than styrene.

Art

#5 jeffs396

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Posted 04 July 2010 - 03:30 PM

You may think low temperatures, but in strong sunlight, in the summer, there can be enough heat buildup even in a styrene part to soften it, cause it to warp, and polyurethane resin is even more susceptible to heat than styrene.

Art


Thank you for the non-condescending reply Art!

#6 Lyle Willits

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Posted 05 July 2010 - 01:44 AM

I gave you a simple, straightforward answer to your question. If you think it was condescending, then maybe your skin is as thin as the resin that's warping.

#7 ChrisPflug

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Posted 05 July 2010 - 05:21 AM

I gave you a simple, straightforward answer to your question. If you think it was condescending, then maybe your skin is as thin as the resin that's warping.


Nope- at least admit you added unnecessary sarcasm as well as not proving any real help....... ;)

Edited by ChrisPflug, 05 July 2010 - 05:25 AM.


#8 Art Anderson

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Posted 05 July 2010 - 06:41 AM

Nope- at least admit you added unnecessary sarcasm as well as not proving any real help....... ;)


Lyle's reply, while curt, is very correct however. I've seen bright sunlight in the summer warp even styrene, especially if it was a dark color, or painted thus.

Polyurethane resin, while a great medium for making model car bodies, accessories (even complete kits) isn't as strong as styrene. It can be warped merely by putting the parts or body shell under stress, be that from stuffing it carelessly into a box, a body shell left sitting on an uneven surface, and certainly by allowing it to get seriously warm--all those things can warp resin stuff.

In my experience though, the tan resins actually can get harder over time. If you leave tan resin body sitting out for long enough, the resin will darken where light hits it (even the cool light of a fluorescent fixture will do this) and the resin will be markedly harder in the darkened portions.

All that said, just exposure over an hour or so, to bright direct sunlight in the summer (no matter that the ambient air temperature was in the 70's!) the infrared rays of the sun heated those parts just enough to allow them to warp of their own weight. An aftermarket resin hood, for example, if it is properly thin, will warp very easily in such conditions--heck, I have seen even styrene hoods painted at all dark, do exactly the same thing.

If you had put your hand on say,the hood of your 1:1 car, no matter that the engine was cold, you likely would have noticed that the sun made it pretty hot to the touch. That is what I am talking about. So, best to do just the painting itself outdoors, then take the plastic or resin parts inside, allow them to dry out of the sun--should be the end of the problem for you.

Art

#9 jeffs396

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Posted 05 July 2010 - 04:00 PM

In my experience though, the tan resins actually can get harder over time. If you leave tan resin body sitting out for long enough, the resin will darken where light hits it (even the cool light of a fluorescent fixture will do this) and the resin will be markedly harder in the darkened portions.


This was part of the info I was after with my original question...are different brands of resin more prone to warpage than others? In my limited usage of resin parts, it seems that the tan resins are more durable than the white, styrene-like resins.