paint over chrome parts

[Blaze00]

I'm looking for advice on how to prep chrome to paint on. I worked with auto paint for over 25 years and know paint will not stick to chrome. I can get some etching primer to stick, but looking for an easier way. I have 5 rims for my 34 Duesenberg SJ and want to get as close to Gary Coopers SSJ as I can. I want to keep the outer bead and center cap chrome and paint the inner gray.

[Bainford]

I have thought about something similar in the past, and wondered if liquid mask would protect some areas of the chrome while the chrome was stripped from the spokes. There are many products that will quickly remove the chrome plating (if not the lacquer undercoat), and the liquid mask may (temporarily?) resist some of them. There are two different types of liquid mask materials out there; the Microscale stuff, and the numerous other products that smell of ammonia. It might be worth experimenting with.

Edited April 8 by Bainford
correct brand for liquid mask

[Mark]

Anything with the ammonia odor will have adverse effects on any model kit plating (vacuum metallizing) that you may wish to save.  Even if you find masking material that won't affect the plating, whatever you try to use to remove the unmasked plating will probably creep under the masking medium.  I'd hand (brush) paint the areas that need to be painted.  If you have to add something to the paint to slow its drying and lose the brush marks in the process, then do that.

[Bainford]

1 hour ago, Mark said:

Anything with the ammonia odor will have adverse effects on any model kit plating (vacuum metallizing) that you may wish to save.  Even if you find masking material that won't affect the plating, whatever you try to use to remove the unmasked plating will probably creep under the masking medium.  I'd hand (brush) paint the areas that need to be painted.  If you have to add something to the paint to slow its drying and lose the brush marks in the process, then do that.

Good call on the products with ammonia. I should have thought of that. 

I would still experiment with the Microscale liquid mask. It is non-injurious to chrome. In fact, I use it to protect chrome parts from over-handling during surgery or modification. The stuff is designed to resist all sorts of paint solvents, so it may stand up to short-term, non-direct application of some chrome stripping products, some of which are quite mild. Especially since the requirement is to just remove the plating to promote paint adhesion, rather than removing the tough lacquer undercoat. As I said above, worth experimenting with. If anyone does try this, I recommend applying the liquid mask nice and thick to make it easier to remove afterwards.

[Blaze00]

1 hour ago, Bainford said:

Good call on the products with ammonia. I should have thought of that. 

I would still experiment with the Microscale liquid mask. It is non-injurious to chrome. In fact, I use it to protect chrome parts from over-handling during surgery or modification. The stuff is designed to resist all sorts of paint solvents, so it may stand up to short-term, non-direct application of some chrome stripping products, some of which are quite mild. Especially since the requirement is to just remove the plating to promote paint adhesion, rather than removing the tough lacquer undercoat. As I said above, worth experimenting with. If anyone does try this, I recommend applying the liquid mask nice and thick to make it easier to remove afterwards.

thanks for the info. I'll try the mask. Thinking I'm in over my head, and not as steady as I used to be

[Oldriginal86]

I’ve had better luck with paint sticking to the chrome then the lacquer under it. I would just mask off what isn’t to be painted then shoot the gray on with the airbrush. How much handling are the wheels going to get?

[Bainford]

On 4/8/2024 at 3:10 PM, Blaze00 said:

thanks for the info. I'll try the mask. Thinking I'm in over my head, and not as steady as I used to be

Be sure to try it out on some chrome sprue from the same kit before committing to the wheels.

[Blaze00]

16 hours ago, Oldriginal86 said:

I’ve had better luck with paint sticking to the chrome then the lacquer under it. I would just mask off what isn’t to be painted then shoot the gray on with the airbrush. How much handling are the wheels going to get?

I dont' have an airbrush, but should be able to dial down my Devilbiss EGA. I'm used to a Sata 95 and a dozen other of my auto

guns (too big). Once painted and assembled I won't touch them

[Skip]

I’ve never tried this, but it might work better than masking and using bleach, purple power, oven cleaner, brake fluid d any other concoctions some use to strip chrome I would be concerned about whatever is used to strip off the chrome to replace under any latex type liquid mask.

My idea would be to use a rather heavy coat of latex and or tape mask. Next use something like a Paasche Air Eraser to blast the chrome off the plastic. I have shot Baking Soda through my air eraser and it is a much milder abrasive than the media Paasche sells

i just remembered when I worked for Boeing, I saw guys doing what is called Chem-Milling, where they use a rubber like masking fluid, (think plastidip the tool handle rubbery dip that sets up like soft rubber).  The rubbery mask would hold the acid that the part was dunked in, leaving a stepped edge like it had been milled away.  Plastidip might work to preserve the chrome but it might’ve difficult to remove.  Might be more trouble than it’s worth…. Good luck and hopefully it gets someone thinking of some other processes they’ve seen.

[peteski]

I really think this "not painting over chrome" thing is way overblown.  It is not like paint will not stick or will flake off.  Really! Some of those "chromed" (actually vacuum metalized aluminum, not the real chromium used on 1:1 cars) parts have a clear coat applied on top for protecting that very thin layer of aluminum. Or if the parts are brass colored, there is a layer of clear yellow/amber lacquer applied over metallic surface to make it look like brass.  Those clear coats don't come off easily.  Paint won't either.

While paint might not adhere as well as it does on bare plastic, the bond will be strong enough to withstand  the handling as well as any paint on the other parts of the model.   You might want to spray a coat of primer first, or even shoot the color coat directly over the metalized parts.  The paint will stick!

I'm not sure where this whole "don't paint over model chrome" started. Maybe because instructions recommend scraping the metal/clear-coat layer off before gluing parts?  Someone assumed that paint wont' stick either?  I don't know, but is it false.

Edited April 18 by peteski

[Can-Con]

15 minutes ago, peteski said:

I really think this "not painting over chrome" thing is way overblown.  It is not like paint will not stick or will flake off.  Really! Some of those "chromed" (actually vacuum metalized aluminum, not the real chromium used on 1:1 cars) parts have a clear coat applied on top for protecting that very thin layer of aluminum. Or if the parts are brass colored, there is a layer of clear yellow/amber lacquer applied over metallic surface to make it look like brass.  Those clear coats don't come off easily.  Paint won't either.

While paint might not adhere as well as it does on bare plastic, the bond will be strong enough to withstand  the handling as well as any paint on the other parts of the model.   You might want to spray a coat of primer first, or even shoot the color coat directly over the metalized parts.  The paint will stick!

I'm not sure where this whole "don't paint over model chrome" started. Maybe because instructions recommend scraping the metal/clear-coat layer off before gluing parts?  Someone assumed that paint wont' stick either?  I don't know, but is it false.

Exactly. "kit chrome" is not even remotely like "real car chrome". 

I've been painting over it for 50 years now, no problem.

If in doubt, go find an old glue bomb model someone has painted over the chrome and see how easily the paint comes off the chrome. 😈

[Blaze00]

On 4/17/2024 at 11:22 PM, Skip said:

I’ve never tried this, but it might work better than masking and using bleach, purple power, oven cleaner, brake fluid d any other concoctions some use to strip chrome I would be concerned about whatever is used to strip off the chrome to replace under any latex type liquid mask.

My idea would be to use a rather heavy coat of latex and or tape mask. Next use something like a Paasche Air Eraser to blast the chrome off the plastic. I have shot Baking Soda through my air eraser and it is a much milder abrasive than the media Paasche sells

i just remembered when I worked for Boeing, I saw guys doing what is called Chem-Milling, where they use a rubber like masking fluid, (think plastidip the tool handle rubbery dip that sets up like soft rubber).  The rubbery mask would hold the acid that the part was dunked in, leaving a stepped edge like it had been milled away.  Plastidip might work to preserve the chrome but it might’ve difficult to remove.  Might be more trouble than it’s worth…. Good luck and hopefully it gets someone thinking of some other processes they’ve seen.

Thanks for advise

[Skip]

On 4/18/2024 at 12:33 PM, peteski said:

I'm not sure where this whole "don't paint over model chrome" started. Maybe because instructions recommend scraping the metal/clear-coat layer off before gluing parts?  Someone assumed that paint wont' stick either?  I don't know, but is it false.

I think your analysis of painting over chrome is a good one.  Plus, modernized painting methods where nearly everything that is painted is also primed to further promote paint adhesion.

If I remember correctly, a lot of it began in the pages of SAE, where the chrome was being removed from kit parts to paint, baring the plastic's details and not for adhesion purposes. Much of the Alclad and the other chrome paints that followed gained acceptance because they replicated chrome in scale better than vacuum chroming and two the chrome paints allowed the surface details to show better than through the "chrome plating".