Best anodizing guide?

[JOGARA]

I think I need to start from the beginning. I have read through a few of the guilds and have gotten mixed up a bit with everything.

From what I have gathered, 6asf is only really for dark colours with large dye molecules, 4.5asf works for pretty much everything?
I should have for 4.5asf a 20-25% acid concentration?


What am I better off doing for my process? I am dyeing black and need it to be a tough enough for a product case that might be battered a bit.
Ill mix up a new batch, using scales but account for the higher weight and concentration.

[JOGARA]

Hang on. I am using Phosphoric not Sulphuric.

Did I mess up?

[Zeeflyboy]

Well you can anodise using phosphoric, but all these guides are based around the use of sulphuric acid. I don't really know much about phosphoric acid anodising but I certainly wouldn't assume the processes are the same regarding concentrations/time/current etc, nor in it's ability to take dyes afterwards.

And no, 20-25% is far too high (for sulphuric, no idea about phosphoric). The caswell guide says 3 gallons water to 1 gallon battery acid, but battery acid is typically only around 32% - when you run the maths that works out to around 1:11 or approximately 9% by volume.

I don't think there is any problem using 6 asf as long as the concentration is appropriate. I have never seen any suggestion that it will struggle to take dye. If you ran 6asf using the same concentration as for 4.5asf then you would potentially end up with a smaller pore size... if you use a lower concentration of 1:15 then you should end up with similar pore size to the 4.5asf at the higher concentration.

edit, out of interest:

Phosphoric acid anodizing is basically used for structural adhesive bonding in high-humidity environments. This process is known as the Boeing Process and is carried out at 10-15 V. The formed oxide film has a greater durability under adverse conditions than film formed in chromic acid and sulfuric acid. One of the reasons for the great adhesive property is said to be due to the morphology of the oxide film, which should be a film of pores with whiskers or protrusions on the top surface of the formed film.

Sounds like the morphology of the surface is different which makes it particularly suitable for adhesives... if the morphology is that significantly different then it could certainly prevent the acceptance of dyes.

[JOGARA]

Off to go buy some battery acid then :p

Thanks

[edit]
Looks about right this stuff
http://www.ebay.co.uk/itm/161904105341

Used these guys last time for my other acid.