Cracks and crevices in a painted model - how to fix these?

[homyakchik]

Yes, believe it or not, I'm an adherent to One-Zero's rule about using the Search function before asking. I saw lots of interesting information, but nothing exactly like this.

I have an Apollo 27 model. I expanded it with a 6" piece of appropriately-sized PVC, and right now (and from across the room) it's a hefty, impressive piece of work (albeit not finished).

In order to get the slightly not-the-same-size pieces to match up, I made heavy use of White/Green/Red putty (toward the end, thinned with fingernail polish remover) and micro-thin styrene strip to fill in the huge gaps, and then (when patience, of which I haven't got a lot, departed) used a combination of dremel sander and sandpaper of various random degrees to smooth these puttied areas out. Before painting, I puttied and sanded something like four times, and to my credit, the thing felt smooth to the touch (it was a combination of unpainted, old white base and sandable dark gray primer, so it was impossible to see the cracks and crevices earlier).

I took my rattle can of Insignia White (Tamiya; my first experience with that venerable brand) and put down the 'final' coat (first experience with Micro Mask, too. Stuff's weird). Unfortunately, when I went back a couple of hours later, I found most of the cracks and crevices now showing quite clearly. If I could figure any way of weathering them to higher visibility I'd just say it was a beaten-up ship rather than a shipyard-mint one. Unfortunately, I'm not that good at weathering yet.

The cracks and crevices range from hairline (literally looking like hairs snaking; next time, I disavow the dremel and patiently use the sandpaper) to things probably a half-millimeter in depth (and some of them show width). Given that the Tamiya went down this thin, I'm uncertain whether additional coats will serve any purpose (at least for filling those gaps).

I've read about thinning the Rainbow Putties (and was doing so), but those apparently dried smooth and then sucked up the paint as they shrank. I've read about thinning styrene glue, but haven't tried it yet. Lots of good reviews about Mr. Surfacer, but it's late and I can't call Hobby Town or Denbeigh Hobby 'til tomorrow to see if they even have any in stock.

My question: given that these are cracks and crevices that are optically sharp (even if my camera won't capture them) on a painted surface, am I going to have to strip the paint off (hopefully not stripping the putties as well) in order to smooth this out? Will any homemade or Mr. Surfacer application work on a painted surface? Should I just sand and fill and paint again (I'm concerned about losing detail; I've already obliterated some hapless rivets)? Is there anything I can do short of stripping the paint and starting again from scratch?

Thanks for anything pointing me in the right direction (and hopefully this counts as Finishing and not Construction).

Davey

[Go Flight]

You can give the paint area a little buff and then hit it with Mr. Surfacer. If the cracks are hairline try Mr. s 1000 if they are a llittle bigger you can use the thicker stuff. Make sure to let it dry thoroughly.

For the putty , the only thing I use anymore is Aves (which isn't really putty). It can be smoothed with water, it doesn't smell, it air dries hard as rock and doesn't crack.

[Kekker]

Since the paint was Tamiya, it was a solvent-based lacquer. The solvent interacts with the putties and causes some swelling, which then leads to cracks.

I've had it happen with primers as well.

I agree with using Mr. Surfacer. I'm pretty sure Denbigh Hobby has it. They also have the Tamiya white putty which is a little thicker than the Mr. Surfacer 500, but nice and white.

Kev

[homyakchik]

Mr. Surfacer (and Aves, if I can find it somewhere) sound like the plan. Thanks, GF and Kekker both.

Davey