Copy Cad still coming out dull grey

[ggerhardt]

Sean,

Thanks for your reply. I sort of hijacked this post as I was having similar problems to the original poster. I think you may have identified my problem, tho - I am not doing the acid rinse after the plating bath. This is the first I've heard that that was req'd, but that makes sense. I'm an analytical chemist, so, I won't have any problem getting nitric or sulfuric acid. I'll make some solutions up tomorrow and try it this weekend.

I'm just plating a part now to give you an idea what a typical part of mine looks like before and after plating. I'll post some pictures later this evening.

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.

Thanks again for your help.

Geoff

[ggerhardt]

Ok, I plated a small part, but this time I doubled the current based upon a recommendation earlier in the post indicating that media blasted parts will require higher currents due to their increased surface area. This improved the quality of the finish quite a bit, particularly around the edges. You might be able to see on the part that the corners are nice and shiny, but the flat surfaces are still matte. I will try a 1% nitric acid dip to see if that brightens them up, then the chromium dip.

Here's the part before entering the plating bath:


Here's it out of the plating bath:
You can see the bits of red towel that stuck to the rough surfaces when I tried to wipe it off, but if you look at the corners, they are quite bright.

[kxkraze]

Geoff,
Based on my experience, the last picture is what the parts look like when the current is still just a little too low. Have you tried turning it up and looking for tiny hydrogen bubbles yet? It looks like you are close. Too little brightener will give a similar result also but it usually isn't just around the edges. Usually, when the brightener runs low, the areas in higher circulation streams tend to be brighter than the areas with less circulation. As Sean said, make sure you circulation pump does not have a filter that is filtering out all the brightener.

Looks like you are making progress in the right direction though -- good job. If you can get that Nitric acid then you are step above what most can do. Sulferic works very well too but Nitric the best. Just keep it away from the sulpheric acid and glycerol !!!!!!!!!

[ggerhardt]

After seeing progress with this part, I did bump the current up again, but did not see any more improvement in the surface finish. The current I had been running at before was definitely too low as I was not seeing the fine bubbles coming off the part. When I turned off the circulating pump, I noticed the bubbles when I bumped up the current. The part with the shiny corners was plated at a current where I just started to see a nice release of bubbles coming off the part. I went 25% higher on the next part without any improvement.

I'll try the nitric acid dip this weekend.

I am using the filter pump that comes with the kit - does that have an internal filter? I don't think so.

Thanks.

Geoff

[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

[ggerhardt]

Sean,

Ok, now I've got it. I brought home some nitric acid, mixed up a 1% solution and dipped the part that I had previously plated (showed in previous pictures). Immediately upon immersion in the nitric acid solution I could see the finish of the part clarify beautifully! I was going to take a picture, but it looked so great wanted to see the chromate result. After the chromate dip it looks just grand (see attachment). Thanks so much for your help. I think I have my process setup now. I've got to clean up my work area and get things organized to start cranking thru the parts now.

Geoff

[seanc]

Geoff:

Makes a big difference, doesn't it? Should be even more dramatic when done immediately after plating, before the part has dried.

Sean

[amobine]

I have been following the thread as it progressed. Since I do not have access to Nitric acid, I will try Muriac acid this week, and see how the parts come out.

I am not chromating the parts afterwards, I am just interested in a "shiny" Zinc finish that I will need on all parts.

[MikeDinWP]

After I plate, I’m good with the brightness of the parts… But after showing some of the bolts and such to car friends… the bolts darkened where they were touched. Is it advisable to dip them in Blue Chromate to protect the finish? I assume that the shorter the dip time, the least “Blue” the chromate adds to the bolt surface, since I don’t want my bolts to be “Blue”.

[MrPontiac]

amobine, ive been using my copy cad system for about a yr. now, every part comes out almost as perfect as i want, i glassbead part,degrease part, then simply polish it up on a wire wheel that i have mounted on my workbench,parts coming out awesome, is this the same prodecure you are using, most carb. parts are cad. plated at 1.5 amps and .7 volts and 90 degree,s, i still don,t like the 110 degree temp. but 90 works great for me. parts are put into a mauratic acid bath for 8 to 10 sec. then washed off with distilled water, then into the electrlite bath for about 8 to 10 min., parts come out awsome for me. Please post a picture of your set-up and maybe we can help you out. e-mail me anytime for help and ill see what i can come up with, ok