Late 50s early 60s Brown Lacquer used on steel cases

Looking for information on the brownish semi-transparent lacquer (or coating if not lacquer) used on US large caliber steel cases in the 50s and early 60s. I’m in the process of restoring several 106mm HEP-T complete rounds and I’m running into an issue regarding the coating on the steel case. I’m trying to find out more info on what type of coating was used, it’s color and if possible, a place to source or how to make the coating so I can restore the casing.

Thanks in advance


From Engineering Design Handbook Ammunition series section 6:

Protective Coatings. Two types of protective coatings are used on steel cartridge cases, zinc, or phenolic varnish. Zinc is prescribed by the Navy and varnish by the Army. The cases are prepared by removing scale, formed during the mouth anneal, as well as shop dirt and any traces of machining oil. The varnish coat is uniformly applied by dipping. After dipping, the coat is air dried prior to baking, in order to avoid thin or bare spots resulting from flow of the varnish on first contact with the heat of the oven. The phenol formaldehyde resin varnish specified for this service bakes by polymerization at a temperature of 400F. The varnish case is tested by pouring 3 liters of Ottawa sand upon the inclined sidewall through a vertical tube, 3 feet long, located 1 inch from the case. The area abraded must not exceed a specified limit. The baking at 400F also serves as a lowtemperature stress relief wich protects against rupture during firing, but does not appreciably lower physical properties. Cases wich are to be zinc plated are stress-relief annealed after the taper but before plating. Before zinc coating, the case is cleaned electrolytically in an alkaline bath. After rinsing, and an acid dip to neutralise all traces of the alkali cleaner, the outside and inside of the case are plated to a thickness of 0.00015 to 0.00020 inch.

I have a 75mm RCL case wich was rusty cleaned and oiled with lijnolie (forgive me I only know the Dutch name) and used a component for drying. It looks nice enough for me.

Its the third case from right. the rest is original.

Amazing information and awesome 75MM collection, Western. Thank you. FYI - I have a US 90MM XM-200 tank case that also seems to be varnished / lacquered a gloss brown.

PS: That silver looking case is really cool.

Thank you very much for the info, I’ve been trying to figure this out for weeks and have spent several hours doing research, but to no availe. I’m restoring 4 HEP-T 106mm complete rounds and will be going to the Marine Supply store to pick up standard spar varnish to spray the casings with. Will post pictures on how it comes out. :-)

Thanks again, this site is the best.