Another Anodising query - sorry

Hi Matt,

Yes the SA was based solely on the OD only so you have a good point there for sure.

The part didn't turn gold/yellow but it did have some kind of residue that I noticed washed off in the de-io rinse before dyeing.

Someone else advised that if you heat the dye to anything above 50°C it would in fact start the sealing process?

Lastly I'm think the aluminium is 6000 series but not 100%. Could the residue actually be smut? If so is there a way to overcome this?
Thanks again
 
Sounds like it didn't get a complete oxide layer or that the pores were too small for the dye to take. Here's what I'd try for troubleshooting:

1. redo the SA calcs and run it again. If it's not gold/ yellow tinged (not so much a colour but a tint - doesn't look plain silver anymore), then
2. get some Ti wire and use that to hang the part

alongside both, do the waterbreak test (there's a video on Caswell Plating website about it) to make sure the surface is COMPLETELY clean. Can't be too thorough about that. Dawn dish soap, scrub, rinse with distilled water, rub down with acetone, rinse with distilled water at a minimum. On the last rinse, the water has to form an even film with no breaks or beading. If it beads/ breaks, clean it again. Wear nitrile gloves while you're doing this.

Are you cooling and agitating your anodising tank? Both are really important to get a good oxide layer.

To seal the part I hold it in the steam above a boiling pan of water for 10min then hold it in the boiling water for another 10min. I heat my dye to 140F (sorry about the 160F earlier, that's for the NaOH) and it's fine.

Smut is dark blemishes - I don't think that's your problem. I think it simply didn't anodise properly.
 
Great thx Matt, I have in fact got some Ti wire that came in the kit I bought. I'll also have to get one of those fish tank aerators and try it all again.
 
no problem! Send me a PM with your email addy and I'll send you pdf of the guide I use.

I used a fish tank aerator hooked up to a loop of tubing that has a few small holes drilled in it, weighted down with a piece of alu plate, plus some old ice packs that I keep in a bag labelled "garage use only" in the freezer. Stick the ice packs in some time before you start, then some fresh ones when you start the run. That'll keep the solution down to a reasonable temp even when anodising somewhat large parts.
 
many good points above. Titanium wire, looks to be one big one. Try Ti rod threaded into the part. I have a build thread over on weapons guild you might read if you are a member there. http://www.weaponsguild.com/forum/index.php?topic=64679.msg866354#msg866354

I did find big differences with back dye source. tried three with the Caswill dye giving the blackest part.

Also found cold bath (mid 60s F) and lower amps for longer time gave a deeper black color.
 
Thanks Carl I'll be sure to check out that forum. Think perhaps Ti rod might be little out of my league for hobby purposes but I'll look into it anyways. As expressed definitely think contact is my biggest worry along with few other minor niggles pointed out by your good selves here on forum. Thank you
 
eBay was my friend for the Ti rod. It worked EXTREMELY well, much better than Ti wire.

here's one offer for $15

another larger rod for $7
 
you can also get Ti screws in different sizes/ pitches from McMaster. I've used those occasionally when a threaded hole was in the right place. Definitely with Karl about the temperature though. Can't remember the precise details but heat is not your friend with the anodising step and you're dumping a fair amount of heat in there with the anodising current. From what I can gather, lower voltage (ie. longer anodising times) = smaller pores but more of them. So you don't want to go too low or the pore diameter will be too small for the dye to enter, plus different dyes have different sizes.

I just stick to the 720 guide on Caswell's site, though sometimes I go for 90min anodising time just because I'm impatient :)
 
Haha yes I understand that for sure, I been waiting 2 hours with my fingers crossed every part I've tried so far.

Need to have to look around cos I'm in UK guys and things don't seem as readily available here as they do out in the US.

Yes I follow the 720 calculator I seen posted on this site actually
 
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