This is sort of an extension of the vibratory tumbling thread. I work in auto restoration. With vintage european cars having the correct nuts and bolts is pretty important. For some reason this doesn't seem to be the case with american cars but if you take a BT7 Healey to a show you will be marked down for having the incorrect markings on the heads of fasteners. Folks get pretty uptight about it so we go out of our way to get it right.
Ok in the last thread I covered tumbling the greasy, grimy and rusty fasteners until they are clean but unprotected. At this point we usually just send them off in batches for clear or yellow zinc plating. Sometimes, like in the case of a Ferrari Columbo V12 the fasteners are all supposed to be finished in black. Our platers do this too but it can take a week or two and sometimes you just need it done today.
Here are some random bits from my Ford 200 motor. Freshly tumbled and then ran through the ultrasonic cleaner to thoroughly degrease them.
The solution they sell you is diluted with water and you are warned that temps below 70 degrees will cause uneven coating and take a long time. I just used hot tap water. The solution was about 110 when I used it. It really is just as simple as tossing the part in. It took all of 30 seconds to do its thing. After rinsing the bolts were a uniform dull black.
then you are directed to "seal" them right away with the provided sealant which happens to be a can of satin clear paint.
and BAM! you get this
Treated and untreated
The camera phone makes it hard to tell but the finish is exactly like what brand new ARP stuff looks like. It looks far better than what our platers provide.
I hit the thrift store and bought a cheap mini crock pot to keep the chemical hot when doing large batches. I am betting we will use this a lot from now on. I also want to try oiling the fasteners instead of clearing them. Particularly if they are going inside an engine.
Next up Zinc plating. We ordered that kit at the same time.