Resin window problem

Resin window problem

Joined: February 27th, 2005, 4:45 am

November 18th, 2010, 4:16 am #1

I'm doing a Monogram 1/48 DC-3 and decided that I'd try the Wally Patented Resin Window method on it. I used some thin shim brass bent to shape to seal the openings, then mixed and poured the resin (Barnes Clear Casting Resin). Everything went according to plan until I pulled the tape and brass off the fuselage, when I found this:



The striated areas have gone quite soft and sticky, and still remain so 48 hours after the resin was poured. It's happened on both fuselage halves. The windows themselves have come out perfectly, and the resin is now fully cured and ready to be sanded down and polished. A Heller C-121 on which I did the windows at the same time has not shown this problem at all.

The resin catalyst is MEK but the proportion is only 1.5% by weight, which is hardly going to affect the plastic. I used scales accurate to 0.001g, so the mixing proportions should be pretty close to spot-on. Besides, the softening has only occurred in certain places, all in areas behind where I put tape onto the fuselage before taping down the shim brass but not everywhere the tape went down.

Anyone got any ideas about what's going on, or how it can be fixed? All suggestions thankfully received ...

A man can't have too many flying boats ...
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Joined: April 29th, 2008, 10:01 am

November 18th, 2010, 4:59 am #2

Dave,

Looks like you may have got some raw MEK on those areas, ie. not from the mixed resin, but spilt, or on fingers etc.

I would also reccomend you use epoxy resin and not polyester, as polyester does dry green, and takes years to fully cure.

Glen

Glen Burns

Creative Models Australia
glen@creativemodels.com.au
www.creativemodels.com.au
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Joined: February 27th, 2005, 4:45 am

November 18th, 2010, 5:24 am #3

... but it's unlikely that I got raw MEK on those areas. They were covered by the brass before the resin was opened let alone mixed, and the mixing (which was thorough) took place well clear of the model. The problem arose after the resin was poured, by which time the fuselage halves were set up to hold them steady during the pour and while the resin was going off. They weren't handled at all for 24 hours after the pour.

It may have been something on the brass, but again that's unlikely because it hasn't happened in all the areas that were covered, and the Heller plastic wasn't affected at all.

Curiouser and curiouser, as Alice would say ...

A man can't have too many flying boats ...
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Joined: June 9th, 2008, 8:31 am

November 18th, 2010, 8:21 am #4

I'm doing a Monogram 1/48 DC-3 and decided that I'd try the Wally Patented Resin Window method on it. I used some thin shim brass bent to shape to seal the openings, then mixed and poured the resin (Barnes Clear Casting Resin). Everything went according to plan until I pulled the tape and brass off the fuselage, when I found this:



The striated areas have gone quite soft and sticky, and still remain so 48 hours after the resin was poured. It's happened on both fuselage halves. The windows themselves have come out perfectly, and the resin is now fully cured and ready to be sanded down and polished. A Heller C-121 on which I did the windows at the same time has not shown this problem at all.

The resin catalyst is MEK but the proportion is only 1.5% by weight, which is hardly going to affect the plastic. I used scales accurate to 0.001g, so the mixing proportions should be pretty close to spot-on. Besides, the softening has only occurred in certain places, all in areas behind where I put tape onto the fuselage before taping down the shim brass but not everywhere the tape went down.

Anyone got any ideas about what's going on, or how it can be fixed? All suggestions thankfully received ...

A man can't have too many flying boats ...
getting some strange outcomes with resin which have not happened before - a huge number of pin holes and a "foaming" on both open and mould covered surfaces - but not consistently. The high humidity is my guess, although I don't see how this would influence your operations.

A man can't have too much info' on the Spanish Civil War
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