Results of acid solution being too hot or something else???

[blackcote]

If any have experienced this I'd appreciate some input. Take a look at the pic here: http://www.caswellplating.com/bbs/al...php?pic_id=569

Does this look familar to anyone? I think the only variable that was changed was the parts were anodized too close to the upper limit of temps (77 ish?) They hovered there quite a while as the temp out side was in the 90's. I was attempting cooling with ice bath around tank, but it wasn't cooling things down... only maintaining temps.

I'm looking for confirmation that I suspect the acid temp was too high, or some other ideas. Thanks.

[sswee]

Are the black marks in the pic pitting? What kind of material? I've run at that temp. range before without that effect, just had problems with dissolution. Only thing similar has been on cast alum. I've had headaches with cast.

[blackcote]

no the black marks are the powdery residue left after I run my finger across the piece a few times. Reminds me of a graphite powder, but finer texture. Almost like a dried version of a dye mixture. This is 6000 series aluminum I'm told. It had a brushed finish on it.

[sswee]

It looks and sounds like smut but I haven't had any problems with 6000 series doing that. I've had some parts made from plate of unknown grade that smutted up and looked similar. If it was dissolution from the high temp, it would've been chaulky pale. If you have many parts of that material, it might help to etch for 1 or 2 minutes before DeOx/DeSmut. I've found it worked for me, especially on beaded or brushed surfaces.
Sorry I couldn't be more help. SS

[destroyer125]

Bringing back an old thread but Im doing a paintball gun body and the body is something making pits....What can I do to make this stop and save the itme Im trying to annodize

[sswee]

Need some more info. Are the pits all over? Whats the parameters of the run? A pic would be useful if you can. SS

[destroyer125]

there everywhere on the piece their tiny black specs but when you look at them thru magnifying glass you can clearly see their little pits in the aluminum.....im running acid bath at 3:1 water/acid ratio 12v at about 4 amps per square foot....acid bath is between 65-75

ive stripped the piece and every time i try to anno it it seems to get more pits....bt it never did thsi before....its like the acid is gettign stronger

[sswee]

Have you tried buffing and polishing the part out after stripping? The black specs sound like the part was impregnated with a contaminate. Something like being blasted with media contaminated with ferrous particles in it.

[destroyer125]

I buffed it yes....But the pits are deeper then what a buffer would normally do....and i rake the wheel clean all the time

I will try to get pics up in the morning....I redid it...and the pits r clearly visible...on the tealish blue colored aluminum...gives it a uniquue look but not what the guy im doing it for wants

[sswee]

What color compound did you use to buff?

[destroyer125]

using tripoli and the jewelers rouge....sry but i didnt get it from caswell....I got it locally

[sswee]

I have had problems on some of the softer alum. when buffing. I rake my wheels often but still have a part on occassion prone to little pits or dimples. They are hard to see on a shiny part but show good after anodize. It took me awhile to find that the wheel had gotten impregnated with residual alum. that was scarring the part back up with these little pits all over on the final buff. When I get these kind of parts, I rake the wheels almost enough to wear them out just raking. Just a possability.

[destroyer125]

what can i do to fix this....I cant sand the gun down....any kind of clear coat to put on it to smooth it out

[sswee]

If that's what it is, I have gone to emory compound on a loose wheel and worked them out leaving a good enough shine to anodize. Acidrain does alot of markers, he might be familiar with this problem and have a better suggestion.

[destroyer125]

anyone know how good the tolerenece is on a DM4 Body?