Advice on repainting mechanism cover

[andylevine]

(Reposting this from the General board, where I got no replies.... thought it may have gotten 'lost')

One of the last tasks remaining on my M100B project is repainting the mech cover. The one that came with the unit was broken and totally wrong. I found one in fantastic shape on eBay several months back, but it was the wrong color and looks to have been repainted itself at least once, as scratches and flaking paint show other colors beneath.

Not sure the best way to approach this.... strip it chemically?? Take somewhere and have them sandblast?? I was afraid to sand at all even with very high fine wet/dry paper in fear of removing some of the detail lines in the cover. I've read elsewhere that brake fluid takes paint off safely, but don't really want this cover to be a guinea pig as I watch it slowly melt away.

Any advice appreciated from those who have done this safely and are pleased with the results.

Thanks and Happy New Year
Andy

[e093116]

Andy,

If the mech cover is steel and was in my shop, I would "media blast" it with aluminum oxide at 50-80 psig.

I wouldn't take it to a "sandblaster" who specializes in cleaning farm equipment, trailers, etc.  The higher capacity, pressure, and "sand" media typically used by "sandblasters" can ruin "delicate" sheetmetal parts...

The aluminum oxide leaves a nice "tooth" on the surface of the metal which helps primer adhere. You won't wipe out any of the detail lines (again assuming the part is steel - you can check with a magnet).

If there are cracks, you should be able to carefully weld them or rig up some sort of patch from the back, I like to use panel bonding adhesive for these sort of patch repairs. Then you can metal finish/fill the crack from the good side, so you won't see it after paint.

I like to clean media blasted items with solvent sprayed on the part to clean the blasting dust off.  The "tooth" on the blasted metal will collect "linters" if you wipe with rags or paper towel and you won't like the painted results.

I'd prime with epoxy primer and cover that with the topcoat or base/clear of your choice.

Depending on how "original" you're trying to be, you might want to color match a good original sample at your local autobody jobber.  I looked at a couple M100B mech covers on them internets and noticed "white" was the typical color, but the older whites are more of a cream/butter color with a lot of yellow in them, you might not like how "white" from a typical spray can will look if you have other original parts on the machine and are trying to match them.

Finally, you might want to "polish" an original sample to get an understanding of the gloss level of the original parts...today's high gloss topcoats or base/clears will most likely be more "glossy" than original...if you go the jobber route for your paint, you can also get a flattening agent to mix with the paint to dumb down/match the gloss level you desire.

Good luck with your project.

Bill

[andylevine]

Thanks for taking the time Bill! Always appreciated....

The original 50's Seeburg covers were Bakelite or plastic, not sure which.... thus my concern of "melting" it if I used some kind of solvent like brake fluid to strip the outer layers of paint. There are several on this one (at least 2 i can see through a few scratches)...they are flaking in places and bubbling in other, basically a horrible undercoat to paint over. As far as colors go, you are correct the 100B (and the A as well) were more of a cream/beige than an off white. I bought a spray can of what is described as "the best" match from one of the usual sources, either Victory Glass or A-1. I am content with putting that on, but want to be assured I have a good foundation to put it on.

Andy

[e093116]

Andy,

If the cover is bakelite, in my experience bakelite is much more solvent resistant than regular "plastic".

I'd test a few solvents in an inconspicuous area and see if any of them cause any harm before proceeding.

I've had good luck using oven cleaner to remove paint on fiberglass panels.  There is also fiberglass specific paint stripper l but I found it didn't work as good as oven cleaner.  Oven cleaner might work for you, you'll probably need to do ~5 applications or more with scraping inbetween before it's clean though.  Don't expect all of the paint to magically melt off with the first application.

I have crushed walnut shells for media blasting, I though this would be the hot ticket for taking paint off plastic, but it was very slow and the media was less "tough" than the bond between the paint and substrate, so it didn't work that good.  I ended up using glass beads, this took care of the paint, but left a frosted appearance.  This might not be too bad if you're going to paint the part...I'd suggest 50 psig blasting pressure and #10 glass beads if you go this route.

I'd stay away from brake fluid.

If you need more aggressive solvents than oven cleaner or fiberglass stripper, regular paint stripper is more aggressive than fiberglass stripper.  I also use "JT501" available from PPG paint autobody suppliers as my general use solvent in the shop (~$20/gal), it will take paint up but will melt/soften most plastics.  I don't think I've tried it on bakelite though.  I've found this works better than acetone, MEK, etc. for my general purpose cleaning/degreasing needs.

You'll probably find that the top paint layer(s) will come off quite easily, but what's left of the original stuff will be much harder to remove.

You might need to try a combination of chemicals and scraping, for the difficult areas (such as in the bottom of one of the character ribs), try scraping with a plastic razor blade, nylon brushes (old toothbrush), nylon pry bar with an edge put on it, etc.  Use metal tools only as a last resort, I have some small screwdrivers with rounded edges on the sides and several sets of different dental style picks that I use to get after those small bits that are really stuck on good, but it is also very easy to scratch the workpiece too.  You might also try locally heating (with a heat gun) to soften stubborn paint, just don't get carried away with the heat!

Spray paint out of a can is much thinner than "real" catalyzed paint sprayed from a gun.  If you need to do any sanding, 600-800 grit is the coarsest you can use without seeing sanding scratches through the paint, especially if you're sanding "back and forth" by hand (linear scratches) compared to random orbital sanding scratches.  Popsicle sticks or other small/thin/relatively rigid items work well as a sanding blocks when you're trying to get into small/delicate areas.

Finally, assuming the stripped part is black/brown in color, you might want to apply a "spray bomb" primer first, this will give you a chance to see if there are any highly visible defects that show up that you don't like (so you can rework), and it will also reduce the number of coats of paint you'll need to apply to "hide" the parent color.  Choose a primer color that is close to your topcoat color for best results if you go this route.

Let us know what happens.

Bill

 

[andylevine]

Bill

Thank you for the detailed response! Exactly the kind of information I was looking for! I love these forums where experts share their wealth of knowledge so all can benefit!!

I have the broken original mech cover that came with my unit that I will try some of your suggestions on before going at it with my good cover. I’m not going for museum quality, but I am a stickler for ‘better than nice’. I’m sure with your advice and a bit of patience I’ll get there

Regards
Andy

[paradisecs]

What about something like Citristrip? It is widely used an Arcade Cabinets to remove layers of paint revealing the original artwork.

[andylevine]

I actually used Citristrip to remove the layers of paint on the cabinet before I veneered. That was one of the things I was going to try on my broken unit before committing to it. Thanks for the suggestion!

[andylevine]

I finally found the time to actually doing this job (well, at least the stripping bit). Thanks to all the help here I am THRILLED wit the results so far. 2 coats of oven cleaner, a short dose of Citristrip and LOADS of elbow grease and I am down to the original black base. A little more scraping to get to where I can respray.



imgur.com/a/HisJW

Thanks to everyone who supplied valuable information

Andy

[Straycatakis]

Hi Andy, I was wondering after reading your post. I have also a B cover that is broken. the right half part is ok, but the left low part that wraps around the left side is missing.
Would you mind giving away your broken one (if you have the part that's missing on mine) so I can fix it complete? just wondering...

[andylevine]

I have most of the bits from the left side (the unit broke where left meets right near tonearm) The had repaired by screwing a metal plate across the major break, but the left side had broken into 4 smaller pieces, then glued together, then the plate held the repaired left side to right side. Not pretty. Also a small fragment of left side was totally missing. On top of that, when I was testing stripping techniques on it, the strippers totally took all the glue away that was holding the parts of the left side together. That being said some patience, some glue and some bondo or JBWeld putty could probably get a usable complete cover out of this. I can send you pics of the pieces if your still interested.

[Straycatakis]

thanjk you for your reply. I sent you a PM