[seanc]

You'll have to give us more specific data for some issues, but:

Have the older cad/zinc kit,25 amp rectifier,fish tank heater.
1) How big of an area can I plate with this??

Part size will depend on:

1. Rectifier: 25 amps will plate 250-300+ sq-inches (using old formula zinc)
2. Anode: anode size >= part size
3. Tank & electrolyte: well, it's gotta be big enough for the parts to fit comfortably & fully submerged

2) When I plated a brake booster (after blasting) I pulled it out and it seemed to have a milky/chauky substance that dried and streaked almost right away.

See #1. How big is the booster? How big are your anodes relative to booster? How many amps was it plated at?

3)Zinc on a couple pieces looked ok when first removed but dulled awhile later

Unless protected, raw zinc will corrode producing a dull white layer ("white rust"). It's relatively soft and will rub off fairly easily. Is this what you're seeing?

Zinc needs to be protected against "white rust". If you're not chromating, soak it in WD-40, or apply some sort of wax/other top coat.

4) Figured out the 'don't remove from yellow chromate and nonchalantely take in the house to rinse(gets darker quick). Can I reblast this and do over?

Possibly. If it's only the chromate you're not satisfied with, that might work. Otherwise, acid strip the zinc plate entirely, and do it all again. I've given up try to "fix" mistakes, found it far easier & better to re-do from the start.

What's best for cleaning parts after blasting?

It's best to thoroughly clean parts BEFORE blasting. Only raw metal & it's corrosion products should ever get into a blast cabinet.

Others may have different opinions, but this works great for me:

1. Clean, degrease, de-crud, strip paint, etc. Not one speck of contamination left anywhere.
2. If heavily rusted, soak in acid pickle (10-20% muriatic) to dissolve the heavy stuff. Rinse & dry.
3. Media blast. Go immediately from blasting to plating. Don't let the parts sit exposed for any more time than necessary to make the transition.
4. Rinse in running water
5. Dip in acid pickle (5-10% muriatic acid) for a few seconds (10-20 sec.) to activate the metal
6. Rinse again
7. plate

Sean