I’m currently building a Trumpeter SM-79 for the RA Group Build. (shameless plug)
The plastic on the tail is peeling off in very thin sheets. [:(!] The area affected , so far is very small. The more I would sand it, the worse it would get. I tried to brush on some Ambroid (liquid cement) hoping it would smooth it out but it just ate through the very thin layers. I was going to try and throw some putty over it but I was afraid it would start peeling once I started sanding with rough sandpaper. In the end, I lighty smeared some more Ambroid over the spot until it was somewhat smooth. I then wet sanded with 800 grit. It’s not perfect and there are still low spots and digs but I’m going to leave it at that for fear of causing more problems. Thinking of laying down a heavy coat of primer in that area and wet sanding with a finer grit like 1200.
Anyone ever run into this problem? If so, what did you do to correct or fix the problem? Seems very strange to me.
Though I have never personally encountered this problem, I have heard others mention it when building their Fonderie Miniatures kits. Hopefully, Aaron (sfcmac) will see this and provide some insight. [tup]
I had the same problem with a Testors-Italeri 1/72 Airspeed Horsa fuselage about a 20 years ago. It was like the plastic was laid down in thin layers and had started to delaminate. I couldn’t repair it, as the area was too large. I had to buy another Italeri kit.
The problem comes from the molds not being properly preheated before the plastic is injected. Most often seen with the first unit or two run off the machine. If it is not too bad then you can just brush some Tenax or similar liquid welder over the surface, let cure then light sand. If it is real bad then go back to your distributor and demand satisfaction, and I mean by replacement, not with a dueling glove [}:)]
The problem can be traced to one of three causes. As Swanny mentioned, molds not up to temperature will cause this, but also, not having all the plastic in the cylinder uniformly to the proper molding temperature prior to injection will cause stratification and delamination. Where recycled plastic is added to virgin, and all manufacturers do this as SOP, thorough mixing is a must to prevent the above problems. All yield approximately the same result, and there’s little the end user can do to rectify the problem.
If there’s only a small affected area, you can try flooding the area with liquid glue or thin CA in the hope that the laminations will re-bond. Much sanding and resculpting will ensue, guaranteed. For larger areas, replacement of the affected parts is your only option.
Thanks for all the info… nice to know what causes a problem like this.
Dogsbody - That is exactly what it seems like!
In the picture below, you can see the affected area (circled in red) after my attempt to fix it with Ambroid and sanding. Like I said before, not perfect but I don’t want to mess with it anymore. You can kind of see the two curved vertical lines where two layers of plastic peeled off. It peeled from there to the top (on that side only), all the way back and a small spot just forward of that. Funny thing is, if you notice the small white circle to the lower left of the red circle, that’s where I filled an opening in the tail with round styrene. That sanded out just fine and the rest of the kit has been a pleasure to sand so far. The plastic is soft and shapes nicely.
Thanks again for all the help… much appreciated! [tup]
