[seanc]

Geoff:

I sort of hijacked this post

Happens all the time, don't worry about it.

I was trying to address amobines problem, as he had initially posted in an earlier thread, but it's good for whoever it helps!

This is the first I've heard that that was req'd,

It's not a requirement, but it sure does make a difference!

From your photos, that plated part looks normal. An acid bright dip will make a world of difference!

While it works to an extent, I've found that sulphuric is the least effective as a brightener. In order of ranking:

1. Nitric @ 0.5-1%
2. Hydrochloric @ 2-3% (I buy Muriatic at the hardware store, but since it's only 30-35% HCl, it's mixed at 5-10 giving me approx. 2-3% HCl)
3. Sulphuric @ 5%. (I use battery acid, which again is already dilute, so mix it @ 10-15%)

Nitric & HCl should only be used on parts getting clear or yellow chromates (both of which are nitric based). Only sulphuric should be used for parts getting black chromate (which is sulphuric based).

Now I'm going to contradict some other recommendations. I have no scientific evidence to back it up, it's purely empirical:

• media blasting does not have significant impact on surface area. I never compensate for it. If anything, I reduce current density.
• "fizzing" is not a reliable indicator of effective plating, because it depends on too many other variables:
  1. electrolyte temperature (warmer = less fizzing)
  2. mean anode-to-cathode (part) distance ( closer = less fizzing)
  3. total part surface area (large surface areas have proportionally more fizzing that small areas at the same current density)
  4. w/ or w/out "brightener" added

Regarding the part you plated above. In my experience, brightness around the edges is due to:

• insufficient brightener, and/or
• too much current!

This last may seem counter-intuitive, but to get into depression and recesses, less current produces more evenly distributed electromagnetic lines of force, allowing more of it to get into areas that aren't sufficiently exposed.

I was looking the pictures of your parts and noticed the basket you used with the screen in the bottom. Do you need to jiggle the parts every once in awhile so they don't get a screen imprint on them? That's exactly what I need as I've got a lot of odd shaped small parts that would not work well in a rotating drum.

That "basket" was a very early experiment, and is a failure. Parts didn't shift around easily enough to get good coverage, and it was very labor intensive.

I have devised something that works fairly well though. See the sticky post:

Best Way to Prep & Plate Nuts & Bolts

And see my solution here:

DIY Plating Barrel

Good luck!

Sean