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Advice please?

Posted: Sat Aug 09, 2014 11:30 am
by ian.cameron
Hello All

Dry build of kit complete with no major problems but need to crack on and get built, so
What size rivet dolly do I need?
What grade of Loctite do you use?
What is best to clean with before painting?
What primer should I use?
Finally, would like to paint gloss green or matt, not sure yet, what is the best paint to use?

Many thanks in anticipation of your help

Re: Advice please?

Posted: Sat Aug 09, 2014 11:55 am
by Stephen White

I can't help with the rivet question but for the rest:

- for thread locking which can be removed with heat: Loctite 243 (blue)

- for permanent thread locking: Loctite 270 (green)

- for bonding rubber to aluminium: Loctite 480 (silicone based cyano)

- for cleaning parts: Upol System 20 de-greaser

- for priming: Upol Acid 8 etch primer

- paint is a matter of choice but if you want to weather, it's best to combine an acrylic as based coat and enamels and oils to weather. If you protect the base coat with an acrylic matt or lustreless varnish, you can then weather to you heart's content without affecting the base. I use Games Workshop Purity Seal varnish - it's a lustreless finish, sprays well from a rattle can and dries quickly. The correct colour for post war British is Deep Bronze Green, which is available in acrylic. I'm not sure about wartime guns but if you look up Mike Starmer on the modelling sites, he's got the definitive answars.

Hope that helps


Re: Advice please?

Posted: Sat Aug 09, 2014 12:12 pm
by ian.cameron
Many Thanks Stephen

Thinking of using 221 Loctite for putting majority of rivets in, used it in the RAF and is not that strong from what I remember.

Will start buying the paints and stuff today and get cracking on the build!

Kind regards

Re: Advice please?

Posted: Sat Aug 09, 2014 6:10 pm
by Dave Boller
Here's my 2 cents if I may. I don't mean to contradict Stephen above, and perhaps he's just as correct. I've always applied acrylic paints for weathering over a dried base coat of enamels. There's a rule of thumb that says you can apply acrylics over enamels, but not visa versa. I know from experience that it can take a very long time for an enamel overlay to dry when applied to an acrylic base; it can remain tacky for sometimes days. Acrylics on enamels however, only a matter of minutes. But it's not just the dry-time difference. Here's my thinking on this. Enamels are an oil-based paint. Acrylics are water-based (with a touch of alcohol). I've heard people on this very forum complain about rusting on the steel compoenants of their kits after awhile, inspite of applying a primer coat. Steel is highly conducive to oxydation (rusting), and water serves as a catalyst for that. I wouldn't be surprised if the water in the acrylic paint is causing some of this. It might therefore be a good idea to lay down that extra coat of oil-based, enamel first (over the oil-based primer coat), then acrylic. Oil, of course, repels water. On a microscopic level, the oil in such paints, never drys 100%; there's always residual traces of it in the paint, even centuries later. This is what gives primers and enamels their protective qualites in preventing rust on steel. But an acrylic over-coat will also serve to protect the enamel under-coat as well. Unlike enamels, acrylics once dry, are extremely stable. Dried Enamel is easily compromised when over-laying with another enamel paint(such as when weathering), or even when contacted by certain cleaners and common household chemicals. I'm not aware of anything that can re-liquidize dryed acrylic paint. It's that stable, and provides a protective barrior over the enamel. Hope this helps.

Re: Advice please?

Posted: Sat Aug 09, 2014 7:17 pm
by Stephen White
Happily, Ian, this is one of those occasions where we can both be right! The principal here is to use a different medium for basecoat and weathering. This allows you to dilute, spread and blend the weathering without disturbing the basecoat. So you can do it either way and Dave has a valid point, which I wouldn't contradict.

My personal view is that acrylics make a better basecoat. Acrylics have pretty well replaced enamels in the automotive and aerospace industries just because they are tougher and better able to protect against corrosion than enamels. It's also significant that the majority of weathering products available to modelers are enamel based. They respond well to thinning and can be used as filters and washes, in combination with pigments. They also have the advantage of being able to combine with oil paints as part of the weathering process.

I think the corrosion issue Dave raises is very unlikely to be a result of using acrylics - the water content has long since evaporated. Where our tanks do suffer from corrosion, it usually result from a mixture of inadequate protection of ferrous metals and the effects of bi-metallic (galvanic) corrosion, particularly of ferrous metals. I use Rocol Oxylube, a dry film lubricant on all shafts and drive trains and I etch prime everything else. Mark advises to avoid using grease, which can attract particles which cause wear and can harbour moisture.

Hope this informs more than it confuses!



Re: Advice please?

Posted: Sat Aug 09, 2014 11:55 pm
by Dave Boller
Ian, this of course is ultimately your call, but I once again have to disagree with a lot of Stephen's conclusions. Commercial industries push for the use of acrylics for one simple reason: it's cheaper than oil-base, and not necessarily better. "Cheaper", is the "true motive" behind a lot of what they do. You don't have to be an Economist to know that anything made with water, as opposed to oil, is going to be a lot cheaper to make. That goes for ANY kind of oil, whether industrial, or food oils. After all, next to air, what's cheaper than water? As for corrosion. Many different things can cause rusting, as pointed out by Stephen. But acrylic paint, even when completely dry, does not loose all it's water content. In particular, the lower underneath areas near the metal surfaces trap and retain the most water longest, since paint dries from the top down (where exposed to the air). Acrylics, dry especially fast. Granted, the amount of moisture is miniscule(on a molecular level), but it doesn't take much or long direct contact to start the rusting process in steel. The combination of iron-alloys (like steel), oxygen and water molecules are highly reactive ionically in forming rust. Oil-base, has no water content at all and even repels it, so why introduce water-base unnecessarily? As you know from watching cars rust, a single tiny chip in the paint (where now the bare steel is exposed to water and oxygen), can slowly grow and rot out whole body sections. This can happen even from underneath the paint layer, beyond the boundary of the original chip. All that's needed, are those 3 mentioned elements. Such could occur with acrylic paint and it's trapped water content as well. I do agree with Stephen in this regard to weathering with "washes", acrylic has poorer thinning, handling and bonding qualities when especially being applied to non-porous surfaces like plastics or metals(you don't need special "weathering paint"). There are ways to help overcome this though. Try to resist the temptation to thin it with just water, a mix of 20% Isopropl and water solution is best. And again, the more painted the surface is already, the better the adhesion when applying; last-coating is best. Acrylics do apply best from an airbrush, as opposed to manual brushing; the best "dusting effects" come from an airbrush. If you don't feel you can get the best weathering effect with acrylic, then by all means use thinned-down enamel (which is all "weathering paints" are anyway)but do so carefully so as not to compromise the base-coat. This is what we did "back-in-the-day" before acrylic paint was even invented. The trick is not to work it too much physically. When dry-brushing the paint, "compromising" is not as problematic. Then, spray flat acrylic clear-coat. Always finish-up with acrylic because of it's stability qualities when dry, which enamel just doesn't have. Good luck on your build.