Refilling engraving on black Barnacks

[wlaidlaw]

Advertisement (gone after registration)

Has anyone tried refilling the engraving on black enamel Barnack cameras with Rose's low melting point alloy (96ºC) or even better Field's metal, an Indium based alloy, (as low as 47ºC melting point). Given that two of my black enamel Barnacks a model II and a model III are rather precious to me, having belonged to my Grandfather and my great uncle, I would not want to damage them. I tried using a silver paint stick and it was not very satisfactory. The alternative is to use Gallistan liquid metal, to paint into the engraving, with very low risk of damage. I only very rarely use the model II but use the model III a fair bit. 

Wilson

[Advertisement]

The Leica Q3 is available for pre-order at B&H Photo Video and Adorama

[alan mcfall]

I believe the original top plates were painted before engraving. As such the engraver tip went through both a layer of paint and then only lightly entered the brass plate. If the paint is worn or removed there is not sufficient depth to fill with the bismuth or a substitute. A complete restoration might involve applying new black paint and reengraving, but that requires templates that hard to find these days.  Some years ago, ok 40, I missed a chance to get a template set, so they are out there and some of the master restores may have them. In all a possibly expensive process.  If the engraved paint is still intact and the filling somehow evaporated, it could be refilled, including with silver paint or the other materials you mention. But this is not the typical way filled engravings are degraded.  Jerzy can provide more specifics.

Here is my early camera  4298a which could be rare due to the "a" suffix briefly used in the early days to denote "patent applied for", I believe. As can be seen with the paint removed the serial in the brass is very shallow. With model II and III you also have all the other engraving beyond the serial.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Edited January 28, 2022 by alan mcfall

[jerzy]

some time ago I spoke to a person in Germany, well known and reputable Leica repair and restoring person who was doing it in the past. Procedure is as you described it, Alan. Items have been black painted (thermo resistant nitro paint), engraved just slightly through the paint, just to scratch the brass (to remove oxidated layer). Within max few hours (to avoid oxidation of engravings) pulverised bismut alloy was aplied on the engravings and then item was heated. Alloy melted and filled engravings, black paint was a sort of isolation. 
When trying to restore the item  you need firstly polish to remove old engravings, and then apply procedure as described above. As Alan mentioned you would need pantograph and templates. But not less difficult is to have appropriate amount of pulverised alloy so that engravings will be fully filled but letters will not be overfilled - what I mean here is for ex in "8" that small circles will not be fully filled with metal. 
I asked this person to restore my top cover of an  early ring Compur - he refused, he said it is better to leave it as it is. The risk to make it even worse is too high.

[MarkP]

I understand that the engravings were filled with a ‘Wismut’ alloy.  I’m currently having a IIIf restored and the black engraving is being redone with a similar treatment.

There is some discussion here (https://www.cameraworks-uk.com/amp/2017/12/02/which-finish-for-my-restoredrepainted-leica) although CameraWorks aren’t doing my camera as at this time they’re not accepting work from outside the UK.

 

[wlaidlaw]

Wismut alloy is better known as Woods metal. It is very rarely used today due to the toxicity and that it can be absorbed through the skin of people who handle it regularly. It has generally been replaced by the less toxic Rose metal, Bismuth based alloys or more recently by Galllium based alloys (I can buy 10g of Gallium on Amazon for £12). However I think Alan is correct on his post above about the engraving now being too shallow to hold the filler, due to wear of the paint/enamel layer. I suspect that is why using a silver metallic paint stick was not satisfactory, with it lasting only a few weeks before most of it had disappeared. 

Wilson

Edited January 29, 2022 by wlaidlaw

[romualdo]

On 1/29/2022 at 5:54 PM, wlaidlaw said:

Wismut alloy is better known as Woods metal. It is very rarely used today due to the toxicity and that it can be absorbed through the skin of people who handle it regularly. It has generally been replaced by the less toxic Rose metal, Bismuth based alloys or more recently by Galllium based alloys (I can buy 10g of Gallium on Amazon for £12). However I think Alan is correct on his post above about the engraving now being too shallow to hold the filler, due to wear of the paint/enamel layer. I suspect that is why using a silver metallic paint stick was not satisfactory, with it lasting only a few weeks before most of it had disappeared. 

Wilson

just been reading an ongoing thread with a contribution by Jerzy

"As 250swb wrote covers were firstly black painted and then engraved revealing bare brass. This was later on filled with bismut alloy (woods metal or similar). It was like this until approx 1939, afterwards engravings were deeper and were filled  with white paint."

So, circa '39 this process (alloy filling) ceased and was replaced by white paint after engraving. Anyone on this board have an original white paint engraved black lacquer (what about WWII grey painted too?) LTM camera - there weren't that many black LTM Leicas made after 1939 - III (near end of production - 400 made in 39), IIIa (800 in toto), IIIg (125) 250 Reporter - so, white painted black lacquered LTM's are not that common?  oops!! forgot about the standard (no black paint bodies after '39)

Edited January 9, 2023 by romualdo

[jerzy]

Advertisement (gone after registration)

romualdo, not exactely what you are asking for, I do not have any pre-war with white paint (apart from post-war conversions), this is my highest number with Wismuth, from 1938. Btw - paint degradation aorund the letteringf may be seen here as well:

 

[jerzy]

... to fast with Enter...

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Grey IIIc were white painted. Possibly all pre-war black painted are with Wismut, I just looked into my Hahne list and found my own notice besides the line with the last batch of black paint III (330001-333300). Note says 330064 still with Wismut.
Maybe Alan has a later camera.
Knobs on my 263841 are chromed though

Edited January 9, 2023 by jerzy

[wlaidlaw]

I wonder if the constituent metals for Wood's Metal became declared as strategic materiel, so no non-military use permitted, hence the change to paint. This happened to aluminium in the UK in 1940 and people were asked to hand in their aluminium pots, pans and other cookware, supposedly to melt down to build aircraft. However this was just a propaganda exercise, as this aluminium was never used for aircraft purposes. Oddly the reverse happened in 1946 in the UK, when aluminium from obsolete and decommissioned aircraft was very plentiful but steel was in short supply. This resulted in the UK government requiring everyone who wanted to buy a new steel bodied car, to get a permit. This was to try and boost exports of new cars.

Wilson

[pippy]

On 1/28/2022 at 5:09 PM, alan mcfall said:

I believe the original top plates were painted before engraving. As such the engraver tip went through both a layer of paint and then only lightly entered the brass plate. If the paint is worn or removed there is not sufficient depth to fill with the bismuth or a substitute...

I don't have anything new to add to this discussion but a few years ago I picked up a 1 Model A to 1 model C conversion which had recently(?) been refinished but wondered about the fashion in which the engravings had been executed. The requisite enamel had been carefully removed and the very shallow engravings appeared to have been filled with something resembling the original Bismuth Alloy. Not knowing precisely the make-up of this alloy I had a look at what Wiki had to say. I did like this bit very much;

"Bismuth was long considered the element with the highest atomic mass whose nuclei do not spontaneously decay. However, in 2003 it was discovered to be extremely weakly radioactive......(it experiences Alpha-Decay)......at such a minute rate that its half-life is more than a billion times the estimated age of the Universe..."...

So not quite up there by comparison to the dangers faced by Leica users with their early 50mm Summicrons?

Philip.

 

[Ling Lee]

On 1/29/2022 at 12:09 AM, alan mcfall said:

I believe the original top plates were painted before engraving. As such the engraver tip went through both a layer of paint and then only lightly entered the brass plate. If the paint is worn or removed there is not sufficient depth to fill with the bismuth or a substitute. A complete restoration might involve applying new black paint and reengraving, but that requires templates that hard to find these days.  Some years ago, ok 40, I missed a chance to get a template set, so they are out there and some of the master restores may have them. In all a possibly expensive process.  If the engraved paint is still intact and the filling somehow evaporated, it could be refilled, including with silver paint or the other materials you mention. But this is not the typical way filled engravings are degraded.  Jerzy can provide more specifics.

Here is my early camera  4298a which could be rare due to the "a" suffix briefly used in the early days to denote "patent applied for", I believe. As can be seen with the paint removed the serial in the brass is very shallow. With model II and III you also have all the other engraving beyond the serial.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Interesting serial number. This is the first time to me that somebody quoted a 4 digit Leica A with a suffix "a" at the end.  I have a Leica A with the same suffix "a" in the serial number and the number is 4267a.  Both winding and rewind knobs have vertical knurlings and feathered arrows.