Leica LTM Filling engravings on a painted surface

Leica M39 screw mount bodies/lenses
Dez

Dez

Bodger Extraordinaire
Local time
3:54 AM
Joined
May 12, 2009
Messages
1,537
Some while ago I bought a beater IIIC with a gummed-up shutter, ruined vulcanite, and very sorry-looking chrome. The plan was to repaint it and create a good looking black conversion. I finally got around to it a few days ago and found the necessary CLA quite easy and everything is functioning well. A replacement vulcanite sheet from Asahi fits beautifully and is easy to apply. But the paint is tricky, as anyone who has tried this knows well.

I stripped the chrome with hydrochloric acid (works great!) and anodized off the nickel using sulphuric acid in battery acid concentration, which is much less dangerous, and not as damaging to the brass. I applied a thin coat of an autmotive primer intended to work on steel and aluminum, with which I have had good luck before. This is a fairly robust matte black, and was suitable for the inside of the base plate. I then shot two thin coats of gloss black nitrocellulose paint. The painted parts look great, and the surface should be fairly tough.

The challenge is the engravings. They are fine and shallow, and this gets much worse with a few layers of paint. There is not much of a "tooth" to hold the white paint stick stuff that I am using to fill them. Also, the paint surface is extremely smooth. I know if I am careful and patient, I can fill the engravings so they look good, but I do not have any confidence in how long the filling will stay in them.

I have seen some very nice looking painted conversions on RFF. My question is whether anyone has tried shooting clearcoat over the surface after filling the engravings. I have tried to keep the total thickness reasonable, so I should not be causing fit problems, but I have never tried this before. Any suggestions?

Cheers,
Dez
 
I'd fill with nitrocellulose with a hyperdermic needle. If you fill with a wax based engravers stick it will melt in the heat and fall out. Some of the other paint sticks never seem to completely dry. If you want to clear coat you'll have to fill with nitrocellulose and clear coat with the same.

Fill the engravings, then wipe off with a piece of cloth 'wetted' with a tiny amount of thinners, wrapped around your finger. It may take a few attempts to get the feel for it.

Don't attempt to do all engravings at once. It could get away on you and you'll have dried white laquer on top of your black laquer. Be careful not to soften the black topcoat too much. You will know as either the cloth will drag or your black paint will be transferring to your wiping cloth. You will have a thin whitish cloud of white paint around the engraving...this is ok and good as you can wipe off with car polish once it's hard.

The fact that you used nitrocellulose will help you in polishing off the cloud. Don't be tempted to use a water based acrylic as it will most likely yellow and fall out.

From what I know, Leica (these days) fill with very thin paint through a hyperdermic, wipe, then let dry then polish off the cloud.

I'd love to see some pictures when you're done!
 
i did the same by using very small tool to drop the white paint on the engraving, and wipe with soft cloth wetted with thinner. Buy you need to make sure the black paint cured properly and will not react with the thinner. Be very gentle on dropping the white paint and wiping it. Try to touch as small area as possible. Have fun !
 
Oh my. These methods appear to be extremely difficult. I have never had any luck with attempting to fill engraving with liquid paint. Either it smears all over the place or the tiny amount on the end of the tool dries before it can be applied. Are you using specialized paint that dries extremely slowly so it can be applied in this way? Lacquer paints, and it seems especially the nitro paint, dry very quickly, in fact a very common problem is a pebbled finish caused by the spray drying before it hits the work piece, so I don't think I can use lacquer as filer paint..

I have noticed that the nitro lacquer is VERY soluble if it even suspects the presence of lacquer thinner. Hopefully this would lessen after the lacquer cures well. Are you filling with something very different from the nitro paint, so that thinners for the white paint would have no effect on the lacquer? What about water-based filler paint? That would seem safer.

I was thinking of using a paint stick. This appears not to be wax based: it acts and smells like extremely thick alkyd paint, and after a day or so dries fairly hard. My big worry is that it is applied over a very smooth and presumably slippery lacquer surface, and so may pop out of the engraving, unless clearcoated. Another worry is that the stuff in its semiliquid form is rather abrasive, and tends to rub some of the black pigment off the painted surface, resulting in a greyish cast.

Cheers,
Dez
 
I just tried using water-based white paint on the engraving on a junk black camera, and I think this could work very well, especially if I dilute it a bit. It looks better than the paint stick, and is not likely to bring along any of the black surface. I'll let the nitro paint on the Leica cure until tomorrow and then try it. Any thoughts on shooting nitro clearcoat over water-based paint in the engravings?

Cheers,
Dez
 
Hi Dez, yes you can usually apply nitrocellulose over a water based acrylic in light coats without it bubbling.

The water based paint may soften then reharden as the solvent evaporates.

You can also use an enamel for the paint fillings...just a lot more time in between applying and then cleaning off the cloud. There is less fear of hurting the black laquer as you can use turpentine as a thinner.

Paint sticks and the like seem to damage the basecoat with the friction needed to apply them. I've never been happy with them. Even applying them into a brass engraving will scratch the brass.
 
One of the few things I did do well with my first try at painting an old M3 to black, was the engravings.

Before the first coat of paint, I used a sewing needle to scratch all the engravings in with. And repeated this after every layer of paint, making sure the brass could vaguely be seen after scratching. By the time I got to filling the engravings with white paint, I had created enough grip for the paint, while not ripping the edges of the engravings.

I'm sorry I did not take a close up shot of the camera before I finally sold it for parts. It had some other issues that could not be remedied economically.
 
This is my second go 'round with the Leica bits. The first time I just stripped down to the nickel with the HCl, but the adhesion was not great. I used a paint stick to fill the engravings, and it was OK, but obviously could have been better. This time I pulled off the nickel with an anodizing bath in battery acid, and got a much better surface for adhesion. I'm letting the nitro cure an extra day this time, and have a try with the water based white paint.

At the moment, I don't have any nitro clearcoat. I am nervous about using a different kind of clearcoat, so should stick to the nitro. As it looks as if the water based white will stick better than the paint stick, I suspect my patience will run out before I get my ordered clearcoat and I'll go with the uncoated version. I will probably regret that.

Cheers,
Dez
 
I don't see any issue with applying a clearcoat on top, as long as you use synergetic paints.

I've applied clearcoats over electronic control panels that were first painted, then engraved and filled. Those were sprayed and baked enamel or powder-coat paints though.

I only have experience with nitro paints on wooden guitar bodies and it usually takes a long time to fully cure. In those cases it's upwards of 5 coats of nitro colo(u)r with fine wet-sanding inbetween though so?
Sometimes clearcoats are also applied on these over the base paints if you want a deep finish.

Good luck anyway, sounds like a fun project :)
 
I have put enough work into fixing up an originally-useless camera, so it really would be a mistake to skimp at the last minute. I have ordered some nitro clearcoat. I only applied one thin coat of primer and two thin coats of black lacquer to be able to still have some depth in the engraving. I'll need the clearcoat to thicken the whole paint job enough to give it some strength. I guess I will just have to find some patience somewhere.

Cheers,
Dez
 
Not too bad

Not too bad

I tried filling the engravings with gloss white water-based paint. This is what it looks like after a first wipe and a moderate amount of rubbing of the surfaces. I'll let it dry for a day, and then get rid of the extraneous white bits.

I found that diluting the paint did not help; in fact it made it more likely that an initial wipe would lift the paint out of the engravings.

DSC_3973_zps41241bce.jpg



For sure I will need to wait until I can top coat it though. The camera was originally in unbelievably bad cosmetic condition, so I am looking for the best possible final product.

Cheers,
Dez
 
In my limited experience the thicker the in-fill paint the better, it sort of makes wiping the excess off easier and gives a cleaner edge. Doesn't sound right when I say it but give it a try on something...other than a Leica.......!

Michael
 
On the electronic panels I mentioned earlier, I didn't do the engraving and filling myself but did see the shop who did the work filling in with paint and wiping off a couple of times.

I didn't think at the time to ask what type of paint was used but do remember that:
1/ There was some sort of grease smeared around the engraving to help keep the build up of extra paint on unwanted areas to a minimum.
2/ The paint was rolled on with a small roller which, I assume, helped with squeezing the paint down into the engraved area.
3/ The painted panel was put under a heat lamp for a while to cure or "go off" a bit before the excess was wiped off.

Your efforts thus far don't look half bad by the way :)
 
I noticed one interesting thing in passing. The first treatment in hydrochloric acid dissolves the chrome quickly, and then slowly attacks the nickel layer. As nickel chloride builds up in the solution, it gradually turns green. This slow etching creates an attractive matte nickel surface that looks a lot like titanium. I am tempted to do this with the chromed bits of the camera, but I would not be able to find a lens that would match, I guess.

Cheers,
Dez
 
Since you have already got the white into the engravings, this is a bit late (sorry), but I would suggest trying the small pots of Humbrol matte paint used on model aircraft. It dries hard and would be compatible with a Nitro overcoat.

Odd paint - supposedly an oil based enamel. but you can thin it with nitro thinner and spray it for a really smooth finish - never worked that out!

If you need to redo anything, it could be worth a try.
 
I have a small amount of Wood's Metal that I bought hoping to try it. The stuff is very easy to work with. The challenge is the engraving process. the original Leica process is reputed to have done the engraving after the painting, leaving a sharp-edged, clean brass surface to which the filler can adhere. I think it was applied as a fine powder, wiped into the engravings, then melted. It won't adhere to a glossy painted surface, though, and that seems to be the limiting factor.

Cheers,
Dez
 
Dez said:
I have a small amount of Wood's Metal that I bought hoping to try it. The stuff is very easy to work with. The challenge is the engraving process. the original Leica process is reputed to have done the engraving after the painting, leaving a sharp-edged, clean brass surface to which the filler can adhere. I think it was applied as a fine powder, wiped into the engravings, then melted. It won't adhere to a glossy painted surface, though, and that seems to be the limiting factor.

Cheers,
Dez
Click to expand...
Dear Dez,

Highlight: that's what I'd always heard, and you're right, it requires clean metal to stick to. I seem also to recall that it was melted onto the top-plate and the surplus poured off, but the person who (I think) told me this died long ago so I can't check.

Cheers,

R.
 
Here's the final product. I think it looks pretty good, and everything works properly, but only time will tell how strong the paint coat is.

BlackLeicaIIIC.jpg


Cheers,
Dez
 
You must log in or register to reply here.
Back
Top Bottom