Well, third time's a charm, it seems. After two lengthy and unsuccessful adventures with a DIY electrolyte set-up, I finally spent the money and bought the Caswell chemicals. It took me almost full day to create a new set-up...
I created all-new baths (distilled water, muriatic acid, MEK solvent, Caswell electrolyte, Caswell blue chromate & Caswell yellow chromate).
Every container was wiped down with alcohol before use, to make sure and manufacturing residue, fingerprints, etc. were gone.
I also replaced my wire wheel (brass) with a new one, just in case the old one had acquired any kind of contamination.
The acid bath was mixed at 1 part acid to 4 parts distilled water
Electrolye and chromate baths were created according to the directions on the Caswell packaging (I didn't buy their manual).and added new ones for the electrolyte and the two phosphates)
I used a fresh, single hoop of Moss-Boss zinc foil
I added 1/2 teaspoon of Caswell's brightener liquid before getting started
No heating used for the acid bath, nor for the two chromate dips
My detergent bath consisted of a 4-qt crock pot full of distilled water, to which I added 400ml of liquid ammonia and a shot of dish detergent. I kept this at about 100 degrees F. Parts were scrubbed with a toothbrush, then rinsed off in a distilled water bath.
The electrolyte bath was kept heated at between 100 - 110 degrees F during plating, with constant agitation using an aquarium bubbler. I pre-heat the solution with a hot water tank heating element, then remove the heater before I start plating. I started at 110 degrees. The temp dropped to about 100 degrees over the plating period.
Plating current was set based on 140mA per sq.in. of part surface. I ran the part for 20 minutes, turning it 90 degrees at the 10-minute mark.
I wasn't actually ready to get started with my first part (a brake line clip from the engine compartment) until about 3:00 Sunday afternoon. The part looked good coming out of the zinc plating step -- full coverage, dull light grey, no burning, no visible edge or corner effects. It got a quick swish in a distilled water bath, then into the blue chromate for a 60 s. dip. After that, it went directly (no rinse) into the yellow chromate dip for a 15s dip. Then a quick rinse with tap water. Then a 1 min. blast with a blow drier (running on HI heat).
I can't tell you what a relief it was to see the part emerge like this...
I'll post some pictures of my set-up later, along with some additional comments about settings and running multiple parts. I haven't tried any large items yet, so that remains an unknown.