January 13, 2012
George Spafford is building a replica of the Yugo M70B rifle using a stub parts kit. A new installment will appear here every Friday
Parkerizing Part 1
Here is the M70 barrel after abrasive blasting. Components that can move, such as the grenade sight and handguard retainer, are repositioned several times during blasting to make sure all surfaces are prepared. Note the plug from Lauer Custom Weaponry has been inserted to block the Parkerizing fluid from entering the gas block. There are also plugs on each end of the barrel.
The parts must be immaculately clean of rust, dirt and oil. I start by soaking parts in acetone and then using brake cleaner with the tube to aggressively clean all the nooks and crannies of the rifle that I can. The idea is to remove trapped cosmolene, etc.
Next, I use my Harbor Freight 40-pound blaster to prep the surface. I do this outside with an asbestos grade filter mask, safety goggles, hood and welding gloves. I kid you not, the media goes everywhere. Some day, I may invest in a blast cabinet but I am quite happy with what I have, provided the weather is cooperating.
At this point, I clean the parts again and let them soak in acetone. Any handling of parts from this point on should be done with rubber gloves to avoid getting oil on the steel and blocking the Parkerizing.
To Parkerize, I actually use a do-it-yourself formula passed to me by a couple of friends. For guys who don't want to make their own solution, Brownells sells a very good Parkerizing system that gunsmiths swear by and it provides instructions.
For the curious at heart, Parkerizing is a process by which the surface of the steel is coated with a very durable phosphate. The process I will outline creates a manganese phosphate layer whose porosity really gives the Molyresin finish a great surface to adhere to.