Thompson Paint

[sprat]

Hi

 

I just purchase a apex 1928 stock complete in good condition. I wanted the metal parts to retro fit another original stock I had purchased in the late 70's. As I removed the cosmoline, I found the black paint literally came off. I then pulled my lend lease kit out of storage and low and behold the buttplate and sling swivels were also painted and it was also flaking

 

the apex good stocks are dirty and lots of cosmo & some light rust , I disassembled the parts to remove the remain gunky cosmo and removed the light rust with bronze wool the buttplate came out nice as did the stock attachment setup.

 

ok so now I have bare metal ??? no bluing!. I noted several parts of the stock release unit are blued others not

 

my question is was the metal on original 1928 thompson stocks

 

blued or painted ?????

 

Thanks

[reconbob]

All Thompson parts were originally blued - not painted. It is quite common

to see areas of M1928A1 parts - especially the so called "Russian" kits - that

have been touched up with black spray paint to make them look better. And of

course to complete the illusion of "virtually new" cosmoline was wiped or brushed

on to cover the paint. An un-forseen side effect of the cosmoline was that it somewhat

dissolves the paint but they didn't care figuring by the time that was discovered the

guns would have been broken down into parts sets and sold.

 

I have handled/processed maybe 200 M1928A1 kits and I would say at least half of

them were touched up with paint somewhere.

 

Bob

[sprat]

Thanks Bob

 

so these parts should be Blued ok thanks again

 

Jack

[2ndArmored]

4140 is the standard material for parts that take a pounding, but wouldn't be necessary for things like the buttstock catch button. Yet to my untrained non-artistic eye, all the little parts look the same color as frame and receiver. Different materials take bluing differently. So did A-O (et al.) make everything from the same metal, or are there different metals that blue up almost to the same color?

[reconbob]

Most steels will look the same when blued (black oxide). I would think that design

engineers would know that the mechanical properties required of a buttplate would be much

different then those required of a bolt for example.

The steel numbering system we are used to (SAE) was not standardized until

long after the M1921 Colts were made. If you look at old drawings - and I believe there

are several in the Tracie Hill book - the steel is specified using a pre-SAE numbering

system. Even U.S. Ordnance drawings refer to "WD" steel which I assume stands for

a War Department numbering system, however I have never found a conversion chart.

So a typical Thompson would have parts made from different steels. There would

be different alloys for parts requiring hardness such as bolts and sears, for barrels, for

receivers, and for common hardware type parts such as buttplates, swivels, and screws.

All of these different alloys will blue almost exactly the same. The color and appearance of

a part also depends on if it is polished, which will make it look blue, or sandblasted which

will make it look black. The hardness of a part does not affect the color when blued.

As an aside, the color of parkerizing is greatly affected by the nature of the steel. The

harder the part, the more carbon in the surface, and the darker the color if WW2 iron-

manganese phosphate is used. For example the hardened blade of a bayonet will be almost

black while the Un-hardened grip will be grey. If you parkerize a M1928A1 receiver the front

half of the receiver which is slightly hardened will be darker than the rear half. But if the same

receiver is blued it will have the same color throughout.

 

Bob

Edited January 3, 2020 by reconbob

[2ndArmored]

God I love this place.

 

Thanks.

[Tiz]

It never ceases to amaze me the amount of collective knowledge contained among the members of this forum. I learn something everyday. It is fascinating to say the least. Thanks

[Black River Militaria CII]

Generally, low carbon steel alloys respond to hot salt nitrate bluing with a very similar black shade, but there are some odd manufacturing processes for shaping mild steel that affect the quality of the black on these parts. An example is the stamped sheet metal Vickers fusee spring cover which comes out a light gray with little apparent penetration of the hot oxide. Some alloys will do this as well and altering the bluing temp or immersion time does not affect the density of the black.

Also, it is not correct that higher carbon content alloys or hardened steel alloys also blue or black the same way as mild hot and cold rolled steel. These alloys often take a very purple-red coloration with hot nitrate salts and without using a special additive and specific processing procedures the purplish color will not go black. The trunnions of MG42s is a good example as it is a very hard alloy and will go purple when hot oxide treated. It is a clear giveaway that such parts have been reblued either on the guns or off.
Another interesting example is the alloy used for the sideplates and some small parts on the Finnish made Maxims. The sideplates go totally purple-red as do some of the small parts like check levers and rollers, etc.The receiver boxes of the Finn made MGs guns I have built and finished require a Duracoat paint to render the receiver box a good, appropriate black finish. There are other examples of various parts on LMGs and HMGs that also go purple due to higher carbon content.

Refinish on Thompsons, other than Colts, is almost entirely parkerizing although I have refinished a number of M1s with Dulite, a black oxide finish similar to what was originally used in production. None of the parts that I blacked with Dulite turned purple which made the work much simpler and it was a relief to me since I didn't have to deal with an alternative finish. FWIW