The Shop > Finishing
Anodizing Bench - starting my own...
aeroHAWK:
--- Quote from: John Rudd on June 04, 2015, 05:26:25 AM --- Are you going to add some colour to your items?.....Blue perhaps? :thumbup:
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Yes, I have dyes for black, blue, red, and yellow. Since the job I showed, didn't require color, I haven't yet set up those tanks. I need to make the bubble manifold and work out the heating (the dyes need to be at 140 deg. F). I have heaters that look like this:
I'm still working on the temperature controller....
--- Quote from: DMIOM on June 04, 2015, 06:13:32 AM ---Your actual anodising tank - you've got your aerating pipes right in the corner - ideal situation to avoid shadows is as close as you can to 360 degree surrounding with the cathode - lead flashing sheet or similar. I would fit the lead lining first and then the pipes on top. Bubbling on its own may not be enough - you may need pumped circulation as well... Note your comments on larger liquid mass reducing probs with heat build - but remember you may need to inject some heat to start with as well.
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Good points Dave. Thanks for the suggestions. Your point about the cathode being 360 degrees has me thinking of making a new one. :thumbup: The bubbles seem to be working well, so it doesn't look like a pump is needed - it's not a large tank. Also, I keep my shop heated year round so the acid tank stays a good temperature.
--- Quote from: DMIOM on June 04, 2015, 06:13:32 AM ---Talking of heat, note you're using coolers - what temp will they safely stand? especially boiling sealant.
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Another great point. I neglected to show that I'm using a stainless steel pan for the sealant tank...
--- Quote from: DMIOM on June 04, 2015, 06:13:32 AM ---(p.s. that's spelt the way the rest of the world does so if you searched anodizing you may have missed that thread! :thumbup: )
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Thanks Dave, I did notice that we Yankees tend to spell things a little differently. I'm still getting used to the spelling of "colour" also (my spell checker doesn't like it).
--- Quote from: Arbalist on June 04, 2015, 11:04:01 AM ---The last anodising I had done was what they called "hard anodising" which is I think done the same way except the acid solution is kept very cold?
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I have considered this too. I found some additive that makes it so it doesn't have to be so cold.
Arbalist:
I used to belong to an Air Rifle club and one of the other members worked at a metal finishing company. Some of the Anodised parts he brought in looked stunning, many of them were multi coloured. One example was a part that was mainly blue but had a random silver "thread" running all over it. Some other items were red and blue. I didn't think to ask how it was done I think it may have involved a wax resist?
aeroHAWK:
--- Quote from: Arbalist on June 04, 2015, 12:34:14 PM ---One example was a part that was mainly blue but had a random silver "thread" running all over it.
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It may be what I understand is "splash" anodizing. I uses a masking solution and bleach to remove unwanted die. Here's a YouTube video:
DMIOM:
Thanks for extra pics Aero. One thing to watch with those heaters is that you don't get the dye too hot, even in just one location. You can (don't ask me how I know!) get the dye too hot, and even just one hot spot can cause a problem. You would think, in general 'chemical' terms, hotter is usually faster which can often be better. The problem is that if the dye is too hot, you can get premature sealing of the oxide matrix you've carefully grown in the ano tank - you may just get a bit of dye in the top of the matrix and it'll "self seal" - but it won't be full-depth, can be particularly noticeable on black dyes where it will look paler and potentially longer-term wear unevenly.
Re circulation etc. in the actual ano tank - your pipes look to have a row of holes on the top. That will give a rising curtain at each side, and will induce some circulation; but depending on the geometry of the part, it may not be enough, particularly if you've got areas where bubbles can be trapped. The actual ano process out-gasses, and if those micro-bubbles get trapped they act as a localised insulator, so you can get an un-even depth of matrix and hence uneven colour if you're dying it. If you're going to stick with just bubbling then you may want to (a) have some holes at varying angles, and (b) consider having some transverse rows across the floor of the tank. I have pumped circulation through a chiller, but also bubble pipes every 2 inches.
There are a few more points (which you may already know about!) in that thread I linked to earlier.
Dave
bertie_bassett:
if I remember rightly, for multi coloured parts you dye the whole thing with the lighter colour, then use bleach to clean off the dye where required, and re colour those areas. followed by sealing with steam.
might be wrong though!
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