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Remove clearcoat from Brass Model
Posted: Tue May 01, 2018 2:53 pm
by Robert
I've always has success using Lacquer Thinner to strip a brass model of it's coating...whether that's a clear coat or a brass paint or even a coat of finish paint. Well today a few parts from my RS-3 NJCB diesel soaked in a LT bath for quite a while, and the finish stay untouched. Looks like a factory clear coat. I'm surprised...any suggestions?
Thanks
Robert
Re: Remove clearcoat from Brass Model
Posted: Tue May 01, 2018 2:59 pm
by herronpeter
My suggestion would be to rough it up in a blasting cabinet with very fine media and use it as the primer coat. That is assuming you are wanting to paint the model. If the solvent won't touch it, it will be a great primer coat!
Peter
Re: Remove clearcoat from Brass Model
Posted: Tue May 01, 2018 3:26 pm
by Robert
Well Pete I think your probably right. It is a surprisingly durable finish obviously not affected by Lacquer Thinner. It's in generally good condition except for small areas of soldering related burn of this "finish". Blasting would eliminate that. I'll see what others come up with before setting a new course. Thank you.
Robert
Re: Remove clearcoat from Brass Model
Posted: Tue May 01, 2018 3:55 pm
by Rufus T. Firefly
Re: Remove clearcoat from Brass Model
Posted: Wed May 02, 2018 1:17 pm
by Robert
Surprised not more comments on this...can't be a rare problem.
Robert
Re: Remove clearcoat from Brass Model
Posted: Wed May 02, 2018 1:54 pm
by Rufus T. Firefly
Robert wrote:Surprised not more comments on this...can't be a rare problem.
I've never had the problem......andI'm perplexed as to what the coating is too.
Re: Remove clearcoat from Brass Model
Posted: Wed May 02, 2018 2:02 pm
by sarge
Robert:
Ask yourself why you want to bother taking it off? Is it just because its the way the "experts" tell you to paint each and every time, or is there a real reason? I don't know who started the bit about stripping clearcoats, or even worrying about tarnish for that matter, as a requirement for a good paint job.
If it's solid and smooth, I call it "primer". NJI used a particularly stout clearcoat, and sometimes it was actually gold paint. Even the usual stuff importers like PSC used I won't bother with if its in good shape. What I am about to put on in its place as primer isn't going to stick any better just because its gray or oxide red.
Moving to tarnish now, if it isn't that pasteflux green mung but just a smooth brown oxide coat, I call that a good key. Just wash it to get the oil off. All this silliness about Barkeepers Friend and Simichrome before painting is worse than nonsense; just makes the primer even less likely to adhere.
If I put a colour coat on and its flawed underneath, I strip with a blaster and aluminum oxide. I just don't bother with all the rest of the witchcraft. If it really needs stripped, then blast away.
BTW, I would not be surprised if some of these clearcoats are early automotive two-pack stuff, often epoxy-base and really stout. What more can you want in a primer-coat?
Re: Remove clearcoat from Brass Model
Posted: Wed May 02, 2018 2:35 pm
by milepost57
I had an NJ custom brass (aka custom trash) model that I tried to remove the clear coating. it was hell trying to get this off. I tried all kinds of powerful strippers and still there was coating residue left on the model. All I could do at that point was to keep applying, soaking and scrubbing until I got it removed.
Re: Remove clearcoat from Brass Model
Posted: Wed May 02, 2018 3:19 pm
by Robert
There's a bit of reason in most of what I do. In this case I'm reminded of an HO Gem NYC F12 4-6-0 model that I owned and did quite a bit of solder work to. It's finish was always a bit of a curiosity, so when I was finished with my alterations I gave it bath in Lacquer Thinner to clean it, and much to my surprise a coat of gold paint came off, and left a clean bare brass finish ready to paint. It also revealed a lot of messy solder work from it's initial assembly, and perhaps that's why it had been coated in gold paint...but I don't know that.
The finish on this RS3 was somewhat reminiscent, and I was convinced a LT soak would wash off a similar finish treatment. Obviously not as I was soon to find out.
Okay beyond that tale of past baths...I have no reason to chase after the finish it currently has. It's a decent surface overall.
Thanks Sarge for the dose of good sense...live and learn is in gear.
Robert
Re: Remove clearcoat from Brass Model
Posted: Wed May 02, 2018 4:15 pm
by Rufus T. Firefly
sarge wrote:Ask yourself why you want to bother taking it off? Is it just because its the way the "experts" tell you to paint each and every time, or is there a real reason? I don't know who started the bit about stripping clearcoats, or even worrying about tarnish for that matter, as a requirement for a good paint job.
Only reason I can think of is that it's on there thick enough to occlude some fine detail after one puts a coat of paint on top of it.
..... I strip with a blaster and aluminum oxide.
Not everyone has that capability, but some wish that they did,
......epoxy-base and really stout. What more can you want in a primer-coat?
I was wondering about an epoxy based material - that would be very tough to remove. Again, if it's thin and uniform, you could leave it.
Re: Remove clearcoat from Brass Model
Posted: Wed May 02, 2018 6:23 pm
by milepost57
also you never know how much dirt is in the clear coating until you start to paint over it.
Re: Remove clearcoat from Brass Model
Posted: Wed May 02, 2018 6:40 pm
by sarge
milepost57 wrote:also you never know how much dirt is in the clear coating until you start to paint over it.
Until you throw a coat of colour on, especially black. Then you
know whether you need to strip it or not, and clear plus colour strips with exactly the same effort as just clear. Grin!
I've painted literally hundreds of models, and precisely one had contaminated commercially applied clearcoat, one of those dreadful early Sam B&O EM-1s. The clearcoat was the least of its issues, by the way...
If lacquer thinner doesn't get it, btw, there are three good options. Stripeez is delightful stuff for the purpose. I did have one Weaver import that I redid from factory paint where Stripeez didn't touch it. Option 2 is brake fluid. That gets quite a few of the auto two-pack clearcoats. Last option is epoxy stripper. That got the Weaver paint after a week's soak.
Re: Remove clearcoat from Brass Model
Posted: Wed May 02, 2018 7:06 pm
by bob turner
I have a PSC Heavyweight Pullman - second run with good roof ends - and the roof started to get psoriasis. Even paint stripper doesn't cut it. I have it under control, but it took a lot of effort.
I routinely bead-blast my models before paint. Be very careful with imports; very thin sheet metal does not do well when blasted. If I am doing .020 brass, I keep it below 35 psi.
Two days is not a lot of time to gather opinions . . .
Re: Remove clearcoat from Brass Model
Posted: Wed May 02, 2018 7:13 pm
by Rufus T. Firefly
bob turner wrote:Two days is not a lot of time to gather opinions . . .
All depends on whether you want opinions or informed opinions,

Re: Remove clearcoat from Brass Model
Posted: Wed May 02, 2018 8:27 pm
by bob turner
He didn't say. He was just surprised at the lack of responses on what might be today's most active thread.