Anodizing questions

[Kaaaaarl]

I have some questions about anodizing and I was wondering if anyone could answer them.

First of all I was wondering if the actual growth of the pours in the aliminium and the sealing of the dye changes the texture/finish of the metal. From what I have read, the desired finish needs to be worked before the process. Is this correct?

When stripping existing anodizing off a marker, does the stripper remove only the anodizing or some of the metal as well?

How many times can an aluminium part be re-anodized?

If two parts of a marker are made from different types of aluminium will the anodizing process result in them being different colours?

Generally, if you were going to make a part for a marker what is a good type of aluminium to get to work with?

Thanks.

[rogalxxx]

I have some questions about anodizing and I was wondering if anyone could answer them.

First of all I was wondering if the actual growth of the pours in the aliminium and the sealing of the dye changes the texture/finish of the metal. From what I have read, the desired finish needs to be worked before the process. Is this correct?

Yes. You have to sandblast the surface to achieve matte finish and polish for smooth one.

When stripping existing anodizing off a marker, does the stripper remove only the anodizing or some of the metal as well?

When left for too long, the stripper will eat the whole metal.

How many times can an aluminium part be re-anodized?

If two parts of a marker are made from different types of aluminium will the anodizing process result in them being different colours?

Achieving the same coulour might be difficult. It's hit or mis generally.


Generally, if you were going to make a part for a marker what is a good type of aluminium to get to work with?

here's the chart of aluminum types :
http://gregers.republika.pl/stopy.html
http://gregers.republika.pl/english.html
and the page itself is quite informative.
I'm going to try anno some parts in my garage this weekend.

Thanks.

[Kaaaaarl]

So I assume the lower the aliminium number the better it is for machining and anodizing?

Are there different types of anodizing? I was reading MCB and somewhere a type 3 or level 3 anodizing was referred to.

[rogalxxx]

check wiki for that. but there are 3 types in general:
type I- soft and scratches easily-easy to make nice colorz
type II- harder and that's what pb guns use-quite easy to make-nice colorz
type II- hardest sh** used for military equipment-hard to make-dark colorz

[Kaaaaarl]

I just did that and it was quite interesting.

Can type III anodizing be done with splash/acid wash effect?

Is it possible to determine the series of an unknown piece of aluminium? Perhaps by working out the density?

[rogalxxx]

Can type III anodizing be done with splash/acid wash effect?

the layer is so thick, that stripping it at places will problably make the other color spots deeper. Apart from that type III anno is quite hard to make. Doing it twice is a bit of an overkill...
I suppose that when making splash anno you either mask the areas for other color or anno whole part, than mask it and than remove new anno and ano it again. I've read that gorilla glue is quite good for masking. I'm sure that profesionals use something else.

Is it possible to determine the series of an unknown piece of aluminium? Perhaps by working out the density?

the differences might be too small. Maybe checking electric conductivity could help.
Cast aluminum does not anno well or at all. There is too much siliocone in it. 

So I assume the lower the aliminium number the better it is for machining and anodizing?

I don't know if there's a rule for it. Generally when it's got more other elements the anno will come out with spots and speckles. The cristals of impurities will affect it.

[Kaaaaarl]

From the wikipedia article it stated that once the anodizing has been done in a light colour it is possible to create an acid wash effect by pouring a dark colour over it before the sealing process but the dyes could resist each other and leave spotted results. It is also possible to print onto the surface of the anodizing before sealing to get photo quality effects.

I think I may look into trying anodizing for myself, it should be fairly cheap and easy to do.

[Have Blue]

Can type III anodizing be done with splash/acid wash effect?

Is it possible to determine the series of an unknown piece of aluminium? Perhaps by working out the density?

Not sure if you can do splash with Type III, but it probably won't look that great.  Type III is done for a really hard, thick anno layer (using a chilled anodizing bath), not for cosmetics.  I'm not sure how much of Type III's color is due to the process, and how much due to dye, but I'm sure a Type III splash (assuming it's possible) would have a very dull, drab appearance.

Density probably isn't the best way to determine the series (hard to get accurate enough) - I recently had an outsourced piece of Al from work that we were trying to determine the properties of.  When we had made the parts ourselves in the past and had them hardcoated locally, they held up great in the field.  But these outsourced Asian parts were failing.  Took a sample to a local anodizer (same place that did the famous tigerstripe splash anno on the old PMI-3/VM-68 when Sheridan was still here in WI, actually) and we found that the part smutted up in the rinse tank immediately to a near black - definitely not the 6061 that we had specified, more likely a 2000 series.

In chatting with Andy (Warped Airsmithing), he noted that a local metal recycler has some sort of gizmo that actually vaporizes a tiny spot on the metal surface with a laser and is able to almost pinpoint the specific alloy based on analyzing the vapor!  Man, I'd like to have a toy like that...

I've thought about trying anno myself, but the thing that keeps stopping me is the inability to do bright dip or electropolish in a home shop environment, which means lots and lots of polishing by hand if you want a 'gloss' finish or are trying to match Phantom parts (which are bright dipped).  If you want an excellent guide to DIY anodizing (including some nifty secrets on doing splashes and other effects), I highly recommend the MoonLite Anodizing Guide: http://www.focuser.com/anodize.html

[Kaaaaarl]

Thank you HB, that was a very helpful post. I am definitely going to look into anodizing a little more before setting something up.

[rogalxxx]

that does it... I just burned my power supply. damn. I'll give up on DIY anno for a while.
Luckily there's one guy who might be able to do it for me-I'll try to get in touch with him.
Meanwhile, does anybody know how can I dispose about a gallon of 30% sulphuric acid?

[Kaaaaarl]

I thought a 15-20% sulfuric acid solution was ideal for type II anodizing, why have you got a 30% solution?

[rogalxxx]

ho, it's 20% my bad.
any idea how to get rid of this stuff?

[Have Blue]

Neutralize it with a base:
http://www.newton.dep.anl.gov/askasci/chem00/chem00693.htm

[Ed]

Use a box of baking soda