Anodizing at home

Started by mhc, April 13, 2019, 11:04:00 AM

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Penn

#15
QuoteThe professional anodizers talk about (on-line) using a solution of phosphoric and chromic acids but chromic acid is difficult to get hold of – and for good reason

Ding Ding

You can't dump this down the drain and also without the correct materials you will notice color changes almost instantly in the sun.  Black will turn blurple is a good example.  Red will turn pink, etc.  

tony

alantani

well, purple and pink are popular colors!!!!!!
send me an email at alantani@yahoo.com for questions!

mhc

Quote from: alantani on April 17, 2019, 03:57:24 AM
well, purple and pink are popular colors!!!!!!

;D ;D ;D - not so much when you were attempting green!

Thanks for the sticky Alan! There seems to be a bit more interest in this topic than I expected - I hope it turns out to be useful for anyone that wants to experiment with DIY anodizing.

Quote from: Alto Mare on April 13, 2019, 04:03:47 PM
I'm glad you're aware how dangerous some of that stuff is, I would be scared to try it at home.
I didn't think it was possible to strip the anodizing.
Looking forward to see your finished product, I have no doubts it will be flawless when you're done with it.

Sal

Thanks Sal, The stripping process is working as well as I had hoped, but putting it back on is a work in progress and still a long way from flawless. You bring up a good point with the safety aspect, I should have mentioned it earlier – Sulphuric acid and Phosphoric acid are corrosive to skin and eyes and need to be handled with care – rubber gloves and eye protection are necessary. Also, when mixing acid with water, always add the acid to the water (AAA). With many acids there is a lot of heat generated when mixed with water, if you add water to concentrated acid the water can rapidly overheat (beyond boiling point) and splutter violently, splattering the area and you with acid. By adding the acid to the water, the heat is generated at a slower rate and is dissipated in the water but still requires caution.

Quote from: Rothmar2 on April 15, 2019, 05:00:47 AM
... I can see plenty more parcels on your door-step in the not too distant future! ;D :D

Quote from: thorhammer on April 15, 2019, 11:23:50 AM
Mike, if you weren't so far away I imagine you'd be getting Ohana parts boxes here directly to color up for us :) From me anyway.

Quote from: David Hall on April 16, 2019, 01:13:41 PM
I venture to guess if he offered to do this for us, he would  have a hundred reels on his porch the first week.

Thanks for your confidence guys, but I think it could be some time before I'll be confident enough to risk doing parts for other members.

Quote from: Penn on April 16, 2019, 01:20:29 PM
QuoteThe professional anodizers talk about (on-line) using a solution of phosphoric and chromic acids but chromic acid is difficult to get hold of – and for good reason

Ding Ding

You can't dump this down the drain and also without the correct materials you will notice color changes almost instantly in the sun.  Black will turn blurple is a good example.  Red will turn pink, etc. 

tony

From what I have read so far, organic dyes (like most fabric dyes) will work but are a lot less color fast than inorganic (metal?) based dyes that are sold as anodizing dye. I am also toying with the idea of a nickel acetate sealing bath that some say is better for sealing the color than a simple boiling DI water bath – other articles I've read say it's just faster with lower energy costs?

Mike
It can't be too difficult - a lot of people do it.

AJ

Sounds like you may have a virus, try running Microsoft malicious software removal tool.  Instructions are available at https://support.microsoft.com/en-us/help/890830/remove-specific-prevalent-malware-with-windows-malicious-software-remo

Do it at least twice!  This will get MOST malware but knot all.

mhc

Quote from: AJ on April 18, 2019, 11:43:51 AM
Sounds like you may have a virus, try running Microsoft malicious software removal tool.  Instructions are available at https://support.microsoft.com/en-us/help/890830/remove-specific-prevalent-malware-with-windows-malicious-software-remo

Do it at least twice!  This will get MOST malware but knot all.

Could well have been a virus AJ, I had tried running reset but it was crashing before it finished - untill I diconconnected the net and reset had time to run and reinstall widows. That was a couple of days ago and it seems to be OK now, I had to reinstall a few programs but it got rid of of the stuff I've installed over the last year or two and don't use. I didn't know about microsoft malicicious software removal tool, thanks for the tip and link - it might be an easier option when it happens next time,
Mike
It can't be too difficult - a lot of people do it.

mhc

Before getting back to the anodizing trials, I tried the phosphoric acid stripping process with a couple of commercially anodized parts. There were two accurate handle arms and two tiburon rod clamps - both the handle arms were pitted to start with, red one in particular was badly pitted under where the counerweight sat. The black rod clamp was new and the other clamp is old but in fair condition.
Before;



After;





The handle arms and old clamp took around the same time as my test pieces but the new black clamp took a few minutes longer than the rest, and there is a small bit of residue left in one internal corner. Don't know if it was just a thicker coating or maybe it was Type III anodizing but whatever the reason, it was still pretty quick and easy.

Mike

It can't be too difficult - a lot of people do it.

Tiddlerbasher

Mike - regarding the virus. Assuming you are running Windows 10 its built in anti-virus (Defender) is reasonable but not perfect. I personally use Malwarebytes (premium). The cost is minimal and it has never let me down. I basically let the program do a complete scan every morning - on a reasobaly modern pc it only takes a few minutes. The program is also very good for online live protection. Cyber crime is on the rise, perhaps that's why there is proposed Federal legislation working its way through Congress.

mhc

#22
Quote from: Tiddlerbasher on April 19, 2019, 09:33:28 AM
Mike - regarding the virus. Assuming you are running Windows 10 its built in anti-virus (Defender) is reasonable but not perfect. I personally use Malwarebytes (premium). The cost is minimal and it has never let me down. I basically let the program do a complete scan every morning - on a reasobaly modern pc it only takes a few minutes. The program is also very good for online live protection. Cyber crime is on the rise, perhaps that's why there is proposed Federal legislation working its way through Congress.

Thanks Chris, after the reset I am relying solely on defender, which may not be enough as you said - I've seen Malwarebytes recommended elsewhere some time ago and will look into it.

Back to the anodizing trials – I've been tossing up whether to post the details of my unsuccessful trials or just wait until I've sorted it out and show the good results (assuming I'll get good results eventually). I've decided to post the results of what I've tried to date; hoping to get some input from others that have, or have tried to anodize at home and also show that for me at least, it is not quite as strait forward as the 'how to' guides might suggest. I'll try to keep the descriptions brief but will include a few notes like the target thickness and current density calculated using the '720 rule' calculator with a few observations on the outcomes.

Next up was to try anodizing some of the stripped test pieces.
Target thickness: 1.0 MIL, 6.0 ASF, Dye: Marawe black (anodize) and idye gunmetal (fabric);



One to remember! Bath temp started at 72F finished at 76F (I don't have any temp control and am relying on ambient temps), Looks like contamination on at least one piece, the black dye was well above 140F and may have started sealing the pores before the dye had penetrated?

Target thickness: 1.0 MIL, 6.0 ASF, Dye: Marawe black (anodize) and diluted idye gunmetal (fabric);



Bath temp started at 73F and climbed to 79F. There is not much improvement - the color is better on the black but there is a patchy cloudy film around the edges that didn't buff out.

Time to step back and re-assess what I'm doing with a bit more searching the net. One of the Caswell forum threads discussed a few of the possible causes of "splotchy" or poor dyeing results.

https://forum.caswellplating.com/forum/anodizing-questions/2454-splotchy-anodize-or-dye-result

One of the causes mentioned was allowing the piece to dry after dying and before sealing – something I hadn't been paying attention to but will be from now on.

'Standard' Type II anodizing uses 12 ASF in a 15-16% sulphuric acid by weight bath, LCD uses 3 – 6 ASF in a 9-10% acid by weight bath. My bath is 12% by weight at the moment, about half way between the two processes, so I thought I would try a current density about half way - 9.0 ASF. It shortens the run time and hopefully reduces the temp variations I've been getting. I also made room in my beer fridge while I was pondering this and cooled the bath before starting, and reduced the target thickness to 0.7 MIL.

Target thickness: 0.7 MIL, 9.0 ASF, Dye: Marawe black (anodize)





The finish is starting to look better – the scratches on the surface were there beforehand. The color is an even gun metal gray but not the black it was meant to be. I'm not sure what caused the darker streak across one piece. The starting temp was 63F and finished at 68F which is on the low side of the recommended temp. I'm not sure if the poor take up with the dye was due to temps being a bit lower than recommended causing smaller pores or the layer wasn't deep enough for black.

Next I stayed with 9.0 ASF but increased the thickness to 1.0 MIL
Target thickness: 1.0 MIL. 9.0 ASF, Dye: Marawe black. The two on the right;



Start temp 65F finished at 72F. Getting darker, but still not black.
Next was to try reducing the current density to 7.5 ASF.
Target thickness: 1.0 MIL, 7.5 ASF, Dye: Marawe black



Start temp 71.5F finished at 73F. Darker again, but still not black.
Next was to go back to 6.0 ASF with 0.7 MIL and give the gray fabric dye another try at the original strong concentration to see if it produces the same black it did earlier.
Target thickness: 0.7 MIL, 6.0 ASF, Dye: Marawe black (anodize) and idye gunmetal (fabric);



Temp started at 73.5F and finished at 78F. This was probably the best result so far – both the Marawe black and fabric dye (long piece) look an even black.
The slow progression towards black showing the last four trials;



I have been persisting with trying to get 1.0 MIL thickness – it's reportedly the maximum thickness achievable with LCD and would offer the most corrosion resistance using the LCD process. Thinking the process was starting to work, I tried for 1.0 MIL with the underhead surfmaster frame.
Target thickness: 1.0 MIL, 6.0 ASF, Dye: Marawe black;





Temp started at 64.4F and climbed to 75F. The result was a good finish with an even dark purple finish.  >:( :) I'll try a higher starting temp with the same settings while I wait for some jet black dye to arrive.

That brings this up to date.

Mike
 
It can't be too difficult - a lot of people do it.

Donnyboat

Great Post Mike, getting more interesting all the time, thanks you, keep it coming, cant get enough, cheers Don.
Don, or donnyboat

Alto Mare

Mike, I love the way you keep trying different settings, you are doing all the hard work for others to enjoy...good job.

I like the way the part came out, I never thought you would be able to do this at home.

Keep it coming...


Sal
Forget about all the reasons why something may not work. You only need to find one good reason why it will.

oc1

I was hoping you were going to teach us all how to do this Mike.  Now I realize that the rest of us will not have the patience.  Good work.
-steve

mhc

#26
Thanks guys, I've got a quick update to let you know I'm still chipping away at this. I tried to replicate the earlier trial that produced a reasonable outcome – 0.7 MIL @ 6.0 ASF and used the Marawe black and the original red fabric dye. The black didn't produce the same 'almost black' result it did earlier and the red looked OK – the four on the left of the following photo;



After trying a few more settings resulting varying shades of gray and dark purple I decided to wait for the new dye before going further. Except for a quick attempt at 'fading in' more out of curiosity than anything;



That's going to need practice  ;D

The new dye turned up last week and I took particular care to follow the instructions to prepare the dye bath, including checking the pH was 6.0 +/- 0.5 and operated at 60 +/- 2 deg C. The first trial (1.0 MIL @ 6 ASF) was better than promising – it was a deep consistent black. I also lashed out and bought some nickel acetate based sealant which is supposed to improve the color fastness of dyes.



Next was to increase the current density to 9 ASF and still aim for 1.0 MIL. The two tiles on the right (After so many trials I've been spending less time on the surface finish before the trial);





It's difficult to photograph black but I can't see any difference between the two results. It's still early but I am (becoming) more confident to start on a few actual parts, more to come.

A bit more of the boring details for anyone that's interested: Something I haven't mentioned is the dissolved aluminium content of the anodize bath - Most of the anodizing forums I've read recommend a dissolved aluminium content of between 5 and 15 gms/litre in the electrolyte to help with pore formation. I have been trying to ignore it, partly because they only stated it 'helps' with dying and partly because a few sites stated the aluminium content will increase as the bath is 'run in' after a few uses. Maybe it takes the 20 or so trials I have done so far to build the Al content up to 5 gms/litre rather than 'a few'.
When I first mixed the electrolyte bath I'm using, I checked the sulphuric acid concentration by following the pH method of titration in the following link https://www.pfonline.com/articles/titrating-sulfuric-acid-anodizing-baths. The pH jumped from less than 3.0 to over 10.0 which would indicate there was no Al present. After my inglorious 7th trial that had multiple problems, I decided to check everything including the acid content of the bath – the sulphuric acid content was unchanged at 11.6% by weight, however this time the pH increase between 3.6 and 10.0 was measurable and showed an Al content of 2.0 gms/litre. It's a very loose correlation but after 20 trials the Al content is probably around 5 gms/litre by now which could also explain why the system appears to be settling down.

Mike
It can't be too difficult - a lot of people do it.

Swami805

Thanks for all this, Looks pretty good from the pictures. At minimum you've got it where it will protect the raw aluminum which is the point of the process,hope to see you hanging a few fish soon!
Do what you can with that you have where you are

mo65

Thanks for researching this Mike...great info for all to use. 8)
~YOU CAN TUNA GEETAR...BUT YOU CAN'T TUNA FEESH~


Tiddlerbasher

Quote from: oc1 on April 19, 2019, 08:42:06 PM
I was hoping you were going to teach us all how to do this Mike.  Now I realize that the rest of us will not have the patience.  Good work.
-steve

Steve - if you do not have the patience - I'm a no hoper :D