pitts in steel

[clydes]

what causes pitting in steel when i strip the plating off manualy .its ok and polished when it goes in but after i strip it has small deep pin hole pits ? and what is the best way to solve this problem. clydes

[dadkar2]

How are you stripping? Are you electro-stripping? What kind of electrolyte?

Kind regards,
Ken

[clydes]

it is normaly after i flash copper then acid cooper then nickel. i just bead blasted them down thats when i notice the deep pin holes and im sure its not from the blasting.
clydes

[dadkar2]

Sometimes if there are any minute pinholes in the flash copper the subsequent acid copper will attack the steel microscopically. It might not be noticeable until the plating is removed.

These pinholes are difficult to avoid and might be caused by insufficient agitation (aeration) or could be due to impurities in the copper solution.

Try eliminating the acid copper step and do all of your build with the flash copper. It will work. It just takes more time in the flash solution, and may require multiple coats (with a sanding in between).

Ken

[clydes]

cool ill try that .that acid copper has been giving me head aches since the start. will a scotch bright pad work to sand ok for a sanding step inbetween flash coppering?

[dadkar2]

If you are simply trying to brush finish something, then Scotchbrite is fine. If you are looking to flatten high spots and irregularities, use Wet-or-Dry sandpaper. Caswell offers the stuff for pennies per sheet.

Ken

[clydes]

thanks ken i will give that a shot. clydes

[mcaswell]

A 'SCRUBBER' finishing wheel will also do a great job.

[clydes]

i have read a lot of people are using this product . ill give it a shot
thanks caswell. clydes

[clydes]

craig at caswell said i would be able to use nickel to build up for the pitting problem as long as i used a buffer layer of flash copper inbetween. has any one had any luck doing this? cydes

[minord]

What I do when all else fails, (on any type metal) is to:

Sand blast. Make sure you have a filter in-line from your compressor to keep oil and krap from being blasted into your new clean surface too. After blasting, (you need to be handling you part with gloves from this point on....) just lightly blow the dust off, then go straight into the flash copper....no rinse.

Flash copper should work fine, but so will nickel. the nickel is simply an unnecessary step in most cases, since flash copper came on the scene. By the way, you need to do all your de-greasing before sand basting, that way you don't bury oily inpurityies into your clean surface.

Also, stay away from latex gloves. I went to using nitryl gloves and eliminated a lot of adhesion problems just by doing that.

Make sure you have the right temerature, a clean surface, proper amperage, and good agitation, (and don't touch part with your hands) and everything should work fine.

Hope that helps!

Dave

[clydes]

you must have to put the copper on really heavey with just blasting it.

[minord]

You got it. Let it go for about 1 hour, then pull it out and rinse and dry it, then get on it with something nasty like 80 grit black oxide paper (wet/dry). I like to do it dry, doesn't seem to make as much of a mess, but you could wet sand it too.

Work the roughness down until you start to see steel, you want to just take the copper off on the high spots. After a couple more hours in the flash copper, you should be able to sand it really smooth without going through the copper.

At that point, I'd go back into the copper for 1 more hour, then sand smooth with 400gr, then polish to a mirror finish. If you go through the copper any place, just de-grease, and hit the Flash Copper again for another hour, and you should be able to get the final shine without going through it again.

Once you get there, all you need is 1 hour in the nickel at 110 degrees, and PRESTO!

Normally steel isn't that big of a problem, but I've had some cast steel parts from old bikes, and sometimes they can really test your resolve. Whenever I get into old stuff, I'll use the previously described method just to save time in the long run, not having to re-do stuff. It is the same method I use for pot metal, and has been pretty fool-proof.

Hope that helps....

Dave

[minord]

Just thought of one more minor little detail:

The method described above is used where tolerances aren't an issue. Remember to mask bolt threads, holes for bearings, etc. The whole Idea here remember, is to get a solid air-tight layer of plating on a piece of metal that won't seem to plate without pitts. Kind of like bondo on a dented fender. You will end up with a very smooth and highly polished surface that is also in most cases very inconsistent as it relates to thickness. Depending on how well you're paying attention as you sand and polish, you'll have any where from .0005" to .005" of plating when you're done, and on a round object, that increases the O.D. by .010". If you "chase the threads when you're done, you now have exposed base metal again!

SOLUTION:

Chase all your threads before you start plating.

Flash Copper for 1 hour.

Remove, rinse & dry, Paint all threads and bearing race areas with plater's mask and let cure over night.

Build the copper up as much as you need to for smoothing and polishing.

After polishing, remove all plater's mask, degrease extreemly well, and rinse with distilled water.

while the part is still sheeting water, go into the nickel LIVE and plate for one hour.

RESULTS: Perfectly plated part, and no thread tolerance issues.

Later........

Dave

[clydes]

thanks dave that was very helpful. it answered a lota questions i have had . great expaination! clydes