Ignorant Anodizing Question

[iamthelazerviking]

I don't fully understand the process, kind of sort of, but let's say you have something already ano'd that has a few raw cuts. Is there a way to just anodize the raw spots only? Or would everything else get ruined?

[Ecapnation]

No, you would still need to strip the base layer then, clear anno, mask the machining, then do the color layer

[glaman5266]

Or if it's black use a Sharpie.

Pretty sure you'd have to have the whole piece done.

EDIT: Well, crap. Now I'm not sure. Ignore me, lol.

[Drcemento]

that would not make total sense when looking a splash anno for instance... where you have to mask and re-dip in multiple colors....

for nics and scuffs I could see the dye not taking at all because it has not been properly prepped, and in the process of prepping it you would strip the previous anno?

thinking about re- doing some old munged up parts that I would strip anyway, but fascinating process and totally doable in my shop

[iamthelazerviking]

Raw ano wouldn't look too out of place on this particular cocker body anyway, plus the cuts would be in the sight rail and between the upper and lower tubes. So leaving it as-is would be fine. Just not sure if I want to molest this or leave as-is 😩

[DocsMachine]

In short, no, you can't "spot anodize" something.

Anodizing, to keep it simple, oxidizes the surface- the process causes the growth of a hydrated aluminum oxide crystal, which until "sealed", is porous. That porosity allows it to absorb and retain dyes. Patterned/splash annos can be done by masking, then dying, or dying, masking, and then dying again. Or acid washes, which dye, then sort of 'rinse' some of the dye away to leave a mottled pattern. Or fades, where one end is dipped in one color, than the other end is dipped in a second color. And so on.

Once it's dyed, the part is basically dipped in a hot plain water bath, which 'seals' the porous surface, locking in the dyes.

If you took an anodized part, milled some cuts into it, and then tried to re-anodize, the electrolytic bath would damage the original coating and dyes.

It's theoretically possible, I suppose, to mask the entire thing except for the cut areas, but I'm given to understand the edges of those cuts would come out badly, probably looking a little corroded.

So if you wanted to color the cut areas, you'd have to do the entire part again, and have the shop mask and do the cuts in the color you want. I'm sure some shops can do that, but I'm also sure that'll cost ya.

Doc.

[Spider!]

but I'm given to understand the edges of those cuts would come out badly, probably looking a little corroded.

This. Visible edges form in the fraction of an inch, if not larger. If they are not white, they are faded or bleed through colors. Plain old lacquer makes a good broad masking coat, but it's very difficult to hit the edges just right (close). Even when you mask and strip after, you get a little action creeping under the mask.

You can use the edge as a "feature". An even edge serves as an outline for a shape or color change. You just have to make the shape something you like. 😬