Here is the above mentioned method for "Restoring" Perazzis taken from an Ithaca Service Manual;
To Repair or Restore Color Case
1; This is a serious problem on guns that have been used extensively.
Equipment Required:
a. Cold blue (we use 44-40)
b. “Q” tips (cotton swabs on a stick)
c. torch or other heat source
d. Paint remover (we use “Kwick”)
e. Fine steel wool
2; Procedure:
(1) Remove everything from the receiver.
(2) Remove lacquer from the receiver using “Kwick” or other liquid paint remover
(3) Wash receiver in a good solvent or boil with detergent.
(4) Using your heat source, heat the receiver to a point where liquid cold blue will dry almost instantly, (about 160°F)
(5) Using a “Q” tip, draw squiggly lines or whatever is necessary to match existing color hardening.
Note* If you have polished the receiver to bare metal, space your lines about ¼” apart on the first pass, then fill in on a 2nd pass.
(6) Using fine steel wool dipped in oil, remove the oxidation from the receiver. Be careful not to remove the color.
(7) Wash in good solvent. Do not touch before applying lacquer.
(8) Spray with acrylic plastic from “Koloid”
(9) Reassemble gun & return to a satisfied customer.
Note** This procedure does not affect the case hardening. It only restores the color. I have used this procedure with Oxpho Blue, which seemed to work as well as the 44-40. The Perazzi was I believe built of an alloy steel, not suitable to case hardening & was simply given a false color from the factory. The old doubles are built of a plain carbon steel, mostly on the order of a 1020 steel, which are suitble for the bone charcoal process. It must always be borne in mind though, any time you put a piece of steel in a furnace & raise it's temperature above it's critical temperature there is a possibility of warpage or cracking. It can be colored by heating to just under the critical temp in a carbon rich atmosphere, BUT, then all the hardness put in by the factory has been tempered out. Personally the guns which I have habitually carried afield were those having little to no case colors remaining. I carry them with pride, use them as they are & have no plans of subjecting them to either process.
The Ithaca process, or equivelent, is no more damaging to the metaluragy than bluing. It can always be simply polished off. It would of course be foolish to pay extra for a gun so done & then polish it off.
There is a process which has been used, in which a concentrated flame from a small accetylene tip heats a small area to temper color the metal in spots. In My Opinion this should be a "Crime". These old double frames were of course given a bone charcoal "Color Case-Hardening" process from the factory, they were not just "Colored". This last mentioned process gives a "Variegated" temper to the case. The hardness of the case does not fade away with the color, but remains intact. This case should not be disturbed unless a total re-heat treat is going to be done. The part should then be annealed, packed in a bone charcoal mixture & heated above it's critical temp to impart the proper hard case upon quenching. If all goes succesful you have an as new appearing frame with the proper case hardness applied. Regardless of what anyone may tell you though, there is some risk involved in puttin'er in the furnace.
