Leica LTM Questions re restoring old black paint Leicas

[chris7521]

A very nice gent named Ken Schultz at Hi-tech Alloy Products http://www.hitechalloys.com/hitechalloys_002.htm
is sending me a Wood's metal sample to experiembnt with in trying to restore an old black Leica. He confirmed that the metal would indeed bond with brass, but that any oil or other contamination on the surface would prevent it from sticking.

So it really looks like the original process of painting then engraving may make a repaint impossible, but I am very much open to suggestions.

Cheers,
Dez

I'm going the same way with my resto of a 1930 black paint Leica. I'm going to experiment a lot before doing it....could be a while till I'm satisfied. We'll see. As is right now, much of my engraving is pretty much flush, with the serial number being worst but still completely readable just not raised anymore.
I'd like it to look as original as possible. I think it can be done. Hopefully by me..and you of course. Good luck!

 

[elmer3.5]

My experience on it!

My experience on it!

Hi, i´ve been working on this for almost 6 years, first in auto restoration now in cameras.

The facts observed:

Endurance of painting, forget about solvent based paintings, because the process can be reverted by accident!
The brass plates have also sharp edges that wont stand use.
Plates are small so if paint sticks to brass surely it wont do it for long because the contact surface is is smaller that its stick capability.
Then the only thing capable will be some recovering that will work mainly like a capsule and secondly will also stick to the brass.

Preparing the surface is essential, of course you have to clean it up very well, and some PU spirit will do.
The most important is to avoid sharp edeges and large(?) plain polished surfaces. for that you can sandblast the parts with a very thin medium, brass is very flexible.

The paint itself is very simple, i´ve learned that powder coating or electrostatic paint is the best way.
1-it doesn´t solve, you can pour on it paint remover and it will last much longer than any other paint.
2-Since it´s powder it will gather up to the part perfectly by electrostatic charge, and then by means of heat it will melt into each other particle making this capsule that will melt also into the little rugged surface after sandblasting.
3-Sharp edges, since you rounded them up, the paint will follow the edges and cover them with a constant layer of paint.

This kind of paint is the one used on machines, auto parts, engines, supermarket furnitures and house hold appliances.
It´s true that lacquer and/or enamel were used on the leicas, i tryed to find them but it was impossible, i searched in industrial paints used in the navy and mines but all of them were intended to be set on the spot (solvent) and maintained periodically, forget about aesthetics. Resins like the ones used in glass fibers can be used also, i think they´re better, but the main iconvenience is applying them, i never experienced beacause there´s no way to put them evenly and since they will cure in a very short term the applying gun will be kaputt quickly.

The letters, well, i´ve observed the lleters on the chrome and black leicas are not the same, it doesn´t matter if they are stamped or engraved, the main issue is the thickness of them!
The black leicas have broader letters.
And i assume the original method was a mix of screening and filling technique, of course i´m not sure about it, if linseed oil will yellow with time you can used your daily salad´s oil, will last months to dry but won´t get yellow, if not go to a local artists shop and search for some convenient paint, it´s full of them.

The process of painting.
This is the hardest part because you have to apply layers considering the use of each part, edges are different from the letters...
With a lot of practice you will end making the pefect match between thick and thin.
Painting the letters also is a pain, and needs practice.

Well, hope this can help you out on how this is made.

cheers!

 

[LeicaTom]

Who here has been painting anything???? I would like to see some finished cameras 😀

Tom

 

[chris7521]

I've been experimenting with painting a Russian camera and as you might guess, getting paint to stick to brass is not an easy task. So , until I get it to work I won't paint a Leica I that I have ready for paint. I have been spaying a lacquer and it goes on beautiful. Super thin and rich looking but, I pick at it after a few days and I can get it to flake. I've done all the prep as I've read. Scrubbed it down with soap and water/"scotchbrite" and then soaked it in mineral spirits and scrubbed it again. All with gloves on and still the same result. If I were to never use the camera it would look extremely nice, but, that's not what this camera deserves and something I could never be happy with.
I,m open to suggestions!

 

[LeicaTom]

I've been experimenting with painting a Russian camera and as you might guess, getting paint to stick to brass is not an easy task. So , until I get it to work I won't paint a Leica I that I have ready for paint. I have been spaying a lacquer and it goes on beautiful. Super thin and rich looking but, I pick at it after a few days and I can get it to flake. I've done all the prep as I've read. Scrubbed it down with soap and water/"scotchbrite" and then soaked it in mineral spirits and scrubbed it again. All with gloves on and still the same result. If I were to never use the camera it would look extremely nice, but, that's not what this camera deserves and something I could never be happy with.
I,m open to suggestions!

Maybe you should let the paint cure longer? ~ Now I figure that the factory didn't have time to waste letting cameras sit around and cure, but I'm also starting to think that the whole "baked" finish is alot of phooey too.......can anyone PROVE that Leitz baked paintjobs in the 1930's and 40's? ~ and you wouldn't have to bake when the paints a nitro-celluose lacquer paint. (which I'm sure was the compound of the WW2 aircraft camouflage paint used in shooting the IIIC and IIIC K camera bodies after 1941)

By what I can tell/see with the really "hasty" built 1944/5 era Leica IIIC K's they were spray painted with one or two coats thin Lacquer (Luftwaffe Paint) and had maybe a rough sandpaper prep between the first coat and second coat thats all.......not a pretty flawless showpiece, but a camera made to work in the battlefield, nothing less, matter of fact the pre 1944 finishes look even better than the 45's so as the war was coming to a close, situations got alot more hasty and after the surrender, I'm sure all Leitz was caring about was selling cameras to keep the factory heating and the workers canteen running!

I don't see any trace of PRIMER, all this talk about primers and I don't think Leica used any primers on the RLM stuff during the war, nothing but brass and paint with paint filling the engravings as well.

The Black paint from they 1930's is a little bit more robust then the RLM Grey was, but it's looking like Leica didn't use primer afterall 😉

So.........how do you make it stick fast to the brass?

Tom

 

[chris7521]

Maybe you should let the paint cure longer? ~ Now I figure that the factory didn't have time to waste letting cameras sit around and cure, but I'm also starting to think that the whole "baked" finish is alot of phooey too.......can anyone PROVE that Leitz baked paintjobs in the 1930's and 40's? ~ and you wouldn't have to bake when the paints a nitro-celluose lacquer paint. (which I'm sure was the compound of the WW2 camouflage paint used in shooting the IIIC and IIIC K camera bodies after 1941)

By what I can tell/see with the really "hasty" built 1944/5 era Leica IIIC K's they were spray painted with one or two coats thin Lacquer (Luftwaffe Paint) and had maybe a rough sandpaper prep between the first coat and second coat thats all.......not a pretty flawless showpiece, but a camera made to work in the battlefield, nothing less, matter of fact the pre 1944 finishes look even better than the 45's so as the war was coming to a close, situations got alot more hasty and after the surrender, I'm sure all Leitz was caring about was selling cameras to keep the factory heating and the workers canteen running!

I don't see any trace of PRIMER, all this talk about primers and I don't think Leica used any primers on the RLM stuff during the war, nothing but brass and paint with paint filling the engravings as well.

The Black paint from they 1930's is a little bit more robust then the RLM Grey was, but it's looking like Leica didn't use primer afterall 😉

So.........how do you make it stick fast to the brass?

Tom

How is the big question! Thanks for your thoughts. I don't think any sort of primer was used either. I'm pretty sure it wasn't magic in how they prepped the brass but, they did something I'm not. I can't get nitrocellulose paint were I live and I can't have it shipped (I live on an island) so unless regular lacquer doesn't stick I'm out of luck for now. Honestly I think it's only a prepping method I need to discover. The cellulose lacquer I believe is just more durable.
I have let the paint dry longer too but, it doesn't seem to make a difference. After 3-4 days it's pretty hard unlike enamel which can take a while. If I ever get it done to my satisfaction I will surely post a picture or two.
Just for the record I don't think 99.9 % of the old Leica's should be touched to refinish. The Leica I am doing someone already had ruined the original paint job . Painting it not once but twice! Silver over black and then black again. Quite a mess. Good 1930 camera under it all though and worth some effort.

 

[chris7521]

Tom,

George Gordon Carr used to bake his restorations in his mothers oven (see the thread on GGC in the screw mount forum).

I guess there might be some truth to the baking story, but maybe Marc James Small can shed a light on this in his forum!?

I think baking just hardens the paint. But, i will look in to the process and why it's actually done. If it indeed helps the adhering then I guess that is my next test. Thanks for you input. I appreciate it!

 

[250swb]

You could try using a black etch primer that will bond to the brass and give a good surface for the black paint. Any rub through or damage will not show a different colour edge if a black primer is used. I would also recommend an acrylic based top coat and not a nitrocellulose paint. In automotive use they both share an acetone thinning agent, but the acrylic is more durable and superceeded nitrocellulose in car paints in the late fifties (although it is still available aftermarket). You shouldn't need to oven dry it, that is for stove enamel finishes. All your paints can be sourced via any good local or internet based car paint supplier.

There is also some confusion to be had in the way Europeans use the word 'lacquer'. So when Leica say a 'lacquer' finish they really mean paint, not a Japanese inspired varnish. Confusion is added in the way some groups of people use the word 'lacquer'. So in guitar circles you have any acetone based paint (solid colour or metallic) called lacquer, and the clear top coat called lacquer, where in the UK only the clear top coat would be called lacquer in general use. So its wise to just say Leica used black paint, but this could have been enamel or nitro........................

 

[chris7521]

You could try using a black etch primer that will bond to the brass and give a good surface for the black paint. Any rub through or damage will not show a different colour edge if a black primer is used. I would also recommend an acrylic based top coat and not a nitrocellulose paint. In automotive use they both share an acetone thinning agent, but the acrylic is more durable and superceeded nitrocellulose in car paints in the late fifties (although it is still available aftermarket). You shouldn't need to oven dry it, that is for stove enamel finishes. All your paints can be sourced via any good local or internet based car paint supplier.

There is also some confusion to be had in the way Europeans use the word 'lacquer'. So when Leica say a 'lacquer' finish they really mean paint, not a Japanese inspired varnish. Confusion is added in the way some groups of people use the word 'lacquer'. So in guitar circles you have any acetone based paint (solid colour or metallic) called lacquer, and the clear top coat called lacquer, where in the UK only the clear top coat would be called lacquer in general use. So its wise to just say Leica used black paint, but this could have been enamel or nitro........................

Interesting, thanks. I don't believe the original paint was enamel.
The lacquer I have been using looks very much like original. Very thin. Which is what I want. I did however try black self etching primer in an attempt to get something to work. Same result but, now a thicker looking paint job. I appreciate the info. I'm not the first one to ever have this problem. Must be the copper in the brass which makes it difficult.

I will eventually figure out something. I'm thinking there is some etching process which will be the key.

 

[john neal]

My guess, having spent some time talking to paint chemists at HMG in Manchester is that the original was a slightly acidic stoving enamel (similar to Black Japan). probably sprayed on quite quickly and put through an oven at anywhere from 100 to 300 deg F.

The engraving followed, with a quick degrease and filling of the letters with Wood's metal - this melts at about 212 deg F, so no damage to the paint would occur.

If you want to try this at a lower temperature, you could try Field's metal, which melts at only 62 deg C (a lot less than the boiling point of water). A soldering flux might be applied to the clean engravings to get the metal to bond. done on a horizontal surface it should produce a meniscus on the lettering, just like the original, as Filed's metal expands as it cools

You can get Field's metal from the same sort of places as Wood's, but the minimum order qty over here is about 20Kg (!). The alternative would be to try to make some - a mix of tin/lead solder and bismuth (shotgun pellets) in equal quantities by weight would be fairly easy to achieve in "experimental" conditions. Just don't inhale the fumes!

The interesting thing about these eutectic alloys is that they melt at a temperature much lower than any of their constituent parts. At less than the boiling point of water, Field's metal becomes a real possibility for restoration of old Leica top plates. The unfortunate part is that the correct stoving enamel is no longer available (due to solvent restrictions) and most current versions are thicker than the original, and will, probably, completely obsure the engravings. However, if you were to clean out the engraving very carefully after painting, so that there is clean brass available for the Field's to bond to, it could just work.

I have a 1931 Model 1 (C) that has little paint left on it. If I ever find the time, I might just try this - I know I can get a really good stoving enamel that is sprayable through my airbrush, but getting my wife to allow me to bake the plates in the oven might be a different matter - 2 hours at 200 deg C with a strong whiff of unpleasant solvents might make it a marriage threatening situation 😉

 

[john neal]

OK, here's some further thoughts on how to get the Field's metal thing to work in practice.

First, produce your home-made your Field's metal:- mix equal quantities by weight of bismuth shotgun pellets and standard plumber's (60/40) tin/lead solder with a little low temp flux and heat gently until it melts together. Don't overdo the heat, we don't want any uneccessary oxidation to occur (hence the flux). I'm guessing that about 270 to 280 deg C will be enough. You may need to adjust the quantities a little, as the amount of tin could be too high - the shotgun pellets will probably be a Bismuth/Tin alloy, rather than pure Bismuth due to cost. It could be that a small amount of pure lead added to the mix would help.

OK - I know that Field's metal should be Bismuth, Indium and Tin, but have you tried finding Indium at the supermarket?

Once this has solidified, find a way to reduce some of it to a powder - rather like iron filings - so scrape, file or whatever to produce the smallest particles you can. You now have a metal "dust" that you can apply to the engravings with a fine tool (toothpick, or similar). Check that it is a eutectic alloyl by dropping some into boiling water and see that it melts and forms droplets.

Clean out your engravings - the best way would be to have them engraved again, so that there is clean brass showing. By "clean" here, I mean chemically clean. Next apply the metal dust to the engravings, make sure you apply enough dust to completely fill the engravings, so that when it cools and expands it will stand just proud of the surface.

Once you have done that, you need to heat the job to 100 deg C to ensure the metal "runs" into the engravings. You could do this by very carefully heating with a blowlamp, but why not put the plate in a shallow tray and fill the tray with boiling water?

My guess is that the metal will fill the engravings and produce that raised appearance - it will not want to bond with the painted surface, but will "grab" the bare brass. I wondered about using some flux to enhance the bond to the brass, but even low temp flux is not effective until about 120 deg C, so it might just get in the way - a point to confirm by experimentation?

Interestingly, Bismuth is considered to be the last stable element in the periodic table - it's very slightly radioactive, dacaying to Thallium, but with an extremely long half-life of 1.9 × 10 to the power 19 years (or longer than the life of the universe, so stable enough for my lifetime!).

If you can pursuade a metals dealer to let you have a small sample of real Field's metal, it will be even easier - it melts at 62 deg C, so the hot water bath would really be the way to go.

Incidentally, why is it that over 90% of all Model 1 bodies seem to have the paint around the serial # scraped off? I will never understand that......

 

[Dralowid]

Quoting John: " Incidentally, why is it that over 90% of all Model 1 bodies seem to have the paint around the serial # scraped off? I will never understand that......"

John, the answer is obvious, they didn't have photoshop in them days...

Michael

 

[LeicaTom]

John did you ever get my email?

Tom

 

[newspaperguy]

FWIW department - baking cures paint faster. Hardens the surface and evaporates the solvents. Check any modern automobile body shop and you will see an oven of some sort in use. (Even for the new waterbourne painting systems - the latest in GREEN technology.)

Segway to - I've used spray epoxy enamel on small metal parts, baked them and finished them with rubbing compound. They looked like factory finish.

Won't use the wife's oven again (But that's a whole different story.)

Bought a small toaster oven at a thrift store for $5. Will be trying a paint job on this old Zorki 1 soon: http://www.rangefinderforum.com/photopost/showphoto.php?photo=128813&ppuser=20714

Two other thoughts.
Brownells.com offers a spray and bake coating for firearms that is supposed to be very tough. Plus, they also offer (sell) a blackening solution for brass. Very easy to use.

 

[john neal]

John did you ever get my email?

Tom

Tom,

Sorry, it had slipped into my spam folder - will shoot you a reply shortly.

 

[PKR]

black chrome?

black chrome?

I haven't used a Leica in some time.I had a black M4. I think it had paint on the brass. I wonder if someone would tell me what "black-chrome" is. Is it black powder-coating.. which is an electrical process like chroming?

 

[chris7521]

OK, here's some further thoughts on how to get the Field's metal thing to work in practice.

First, produce your home-made your Field's metal:- mix equal quantities by weight of bismuth shotgun pellets and standard plumber's (60/40) tin/lead solder with a little low temp flux and heat gently until it melts together. Don't overdo the heat, we don't want any uneccessary oxidation to occur (hence the flux). I'm guessing that about 270 to 280 deg C will be enough. You may need to adjust the quantities a little, as the amount of tin could be too high - the shotgun pellets will probably be a Bismuth/Tin alloy, rather than pure Bismuth due to cost. It could be that a small amount of pure lead added to the mix would help.

OK - I know that Field's metal should be Bismuth, Indium and Tin, but have you tried finding Indium at the supermarket?

Once this has solidified, find a way to reduce some of it to a powder - rather like iron filings - so scrape, file or whatever to produce the smallest particles you can. You now have a metal "dust" that you can apply to the engravings with a fine tool (toothpick, or similar). Check that it is a eutectic alloyl by dropping some into boiling water and see that it melts and forms droplets.

Clean out your engravings - the best way would be to have them engraved again, so that there is clean brass showing. By "clean" here, I mean chemically clean. Next apply the metal dust to the engravings, make sure you apply enough dust to completely fill the engravings, so that when it cools and expands it will stand just proud of the surface.

Once you have done that, you need to heat the job to 100 deg C to ensure the metal "runs" into the engravings. You could do this by very carefully heating with a blowlamp, but why not put the plate in a shallow tray and fill the tray with boiling water?

My guess is that the metal will fill the engravings and produce that raised appearance - it will not want to bond with the painted surface, but will "grab" the bare brass. I wondered about using some flux to enhance the bond to the brass, but even low temp flux is not effective until about 120 deg C, so it might just get in the way - a point to confirm by experimentation?

Interestingly, Bismuth is considered to be the last stable element in the periodic table - it's very slightly radioactive, dacaying to Thallium, but with an extremely long half-life of 1.9 × 10 to the power 19 years (or longer than the life of the universe, so stable enough for my lifetime!).

If you can pursuade a metals dealer to let you have a small sample of real Field's metal, it will be even easier - it melts at 62 deg C, so the hot water bath would really be the way to go.

Incidentally, why is it that over 90% of all Model 1 bodies seem to have the paint around the serial # scraped off? I will never understand that......

Good info. The reason I found my paint would flake is because I plan on filling the engravings with woods metal. Cleaning them out revealed the adhering problem. I like the powder method John. That may work. Working while it's molten hasn't worked for me in my experimenting. It is hard to deal with and beads up like mercury. The woodsmetal I have melts around 190 F so warming the might not affect whatever paint is used.
My thought on why there is often paint loss around engravings is the bass is somewhat exposed on the edges of the filled engravings causing some oxidation over the years. That's all I can come up with.

FWIW department - baking cures paint faster. Hardens the surface and evaporates the solvents. Check any modern automobile body shop and you will see an oven of some sort in use. (Even for the new waterbourne painting systems - the latest in GREEN technology.)

Segway to - I've used spray epoxy enamel on small metal parts, baked them and finished them with rubbing compound. They looked like factory finish.

Won't use the wife's oven again (But that's a whole different story.)

Bought a small toaster oven at a thrift store for $5. Will be trying a paint job on this old Zorki 1 soon: http://www.rangefinderforum.com/photopost/showphoto.php?photo=128813&ppuser=20714

Two other thoughts.
Brownells.com offers a spray and bake coating for firearms that is supposed to be very tough. Plus, they also offer (sell) a blackening solution for brass. Very easy to use.

The heat is used for curing yes. I think a primary use for it in body shops is to minimize the time you will get dust in the paint. And of course with that, the car can be handle much sooner. Not so sure it does much for the adhering.
I wish I could get gun paint here because I thought it would probably work well. But it's hazmat and unless the local gun shops have it(which they don't) I can't have it shipped where I live. Every thing comes by air. Thanks for all the info guys. I still think is all in the prep.😕

 

[John Shriver]

Try pickling with Vinegar. Try baking the paint. But it's hard -- look at the troubles folks have painting brass model railroad models.

 

[chris7521]

Try pickling with Vinegar. Try baking the paint. But it's hard -- look at the troubles folks have painting brass model railroad models.

It's worth a try I guess. I think I remember reading a short bath in hydrochloric acid with a rinse. I have brass to experiment on so no worries if it doesn't work!
Hows the weather in Arlington...hot August heat? I grew up southwest of Boston and I have to tell you I don't miss 95f and humid🙂

 

[Dez]

Nitrocellulose lacquer, and other stuff.

Nitrocellulose lacquer, and other stuff.

I have been able to buy black nitrocellulose lacquer from ebay with no problems. It appears to be used for musical instruments these days. It looks absolutely correct when compared to the original Leica black paint. I do not recall if it was delivered by USPS or UPS, but there did not seem to be any special measures taken.

Wood's Metal can be had in very small quantities from United Nuclear
http://www.unitednuclear.com/index.php?main_page=product_info&cPath=16_17_69&products_id=213

I would very much like to try the process for refilling the engravings on a repainted camera with Wood's Metal; does anyone have some good advice on how to clean out the engravings after painting?

About the notion of primer.....I have a nice old model A Leica which is in good shape but for some areas on the base plate where the paint appears to have been replaced by red ferric oxide primer! I expect rather than an actual primer, this is some sort of exotic patina/corrosion of the brass. It is extremely tough.

One of these days, I will convince myself that redoing the paint on a 1928 camera is not some kind of desecration, and get rid of that red stuff.

When painting brass, I go over it with very fine steel wool, and then pickle it in sulphuric acid. I suspect the latter treatment does not actually do anything, but since you do the same thing before plating, I figure it can't hurt. After doing all that, the paint sticks if it feels like it.

Cheers,
Dez