Anodizing at home

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

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mhc

I'll start off by saying this is in no way meant to be a 'how to' post - I am a complete novice at anodizing who has recently started doing a few home trials to see if the process is as easy as the multitude of 'how to home anodize' guides on the net would suggest. The intention is to share my experiments and invite others that have tried anodizing to share their experiences as well as any advice, suggestions, tips, criticism, etc.

I'll give a little background to the process I'm trialing. Many of the 'how to' guides reference the Caswell low current density system (LCD) which appears to be a widely used home anodizing system (I don't have any affiliation or arrangement with Caswell but I did find their free online guide useful http://www.caswellplating.com.au/LCD.pdf). After sifting through a few of the online 'how to guides', I found this YouTube 'how to' guide



to be a good one to start with – it explains the basic LCD process and is pretty simple to follow.  More or less following that guide and using the '720 Rule Anodizing calculator' from Caswell's support forum to determine amperage settings and run times,  http://www.ndhsubmersiblescience.com/ano/720rule.html my initial few trials were encouraging at first but later trials were not as successful.

My tank set up;
•   Constant current power supply with 5 Amp / 30 Volt capacity
•   Two lead sheet cathodes and titanium racking wires connected to an aluminium bar
•   12% by weight H2SO4 bath (dilute battery acid)
•   Cheap aquarium air pump and aerator disks to agitate the bath





The first three trials with the red dye were timed to produce a 0.5, 0.7 and 1.0 MIL layer (1 MIL is approximately 0.001" and around the limit of LCD) at 6 ASF from left to right in pairs;



I then tried a gray colored fabric dye while waiting for black anodizing dye to be delivered. The dye was obviously a bit too concentrated and turned out black;



The dye took well, but the finish was not uniform with blotchy areas around the edges. I also anodized (clear/silver) the frame components for an under-head surfmaster although the connection failed on one of the spacer bars and will need to be redone.



I'm having a few issues with Windows 10 randomly shutting down and will continue when I
It can't be too difficult - a lot of people do it.

mhc

#1
OK, I've hijacked my wife's computer for a minute;

Before going too much further with the trials, I wanted to check the anodizing can be removed easily without damaging the part - one of the main reasons I am attempting this is to strip parts and re-anodize them after repairs or modifications. The 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, it's pretty nasty stuff. I found a few posts on blogs and forums that claimed phosphoric acid will work on its own if heated to between 175F to around 212F (the recommended acid concentration varied from 20% to around 80%) it removes the anodize layer without being overly aggressive on the raw aluminium underneath. Caustic soda (NaOH) is very effective at removing anodize but is also aggressive with the raw aluminium. The following link to a finishing forum thread has several different suggestions, including phosphoric acid https://www.finishing.com/20/76.shtml . The process I ended up using is pretty simple, suspend the part on titanium wire, dip in >170F acid and monitor the stripping and rinse when done. I've found it's easier to do one piece at a time, it only takes a few minutes and each piece can vary in timing. The phosphoric acid i'm using is around 60 - 80%, it's sold as pH Down and is used to adjust the pH level in hydroponic systems. There is also pH down products that are based on citric acid, hydrochloric acid and other oxidising agents, if you want to try this be sure to get the phosphoric acid version.
The set-up is simply a heat source and heat proof container;



The acid takes around a minute to dissolve the anodize, depending on the thickness, then another couple of minutes to remove it all;





The final stages of the process look like the reaction is more aggressive than it actually is;





And after a quick rinse under a tap;



The dye in anodizing will not necessarily penetrate the full depth of the layer so color removal alone is not a sure indication the anodize has been completely stripped. Since anodizing is non-conductive, a simple test with a multimeter to check conductivity of the surface can be used to check the anodize has been completely removed – if there is any resistance there is still part of the anodized film remaining.



At first I thought this piece had been left in the acid too long and had started to etch;



It turned out there were still a few patchy areas of anodizing left;



Another short time in the acid cleaned it up;



One piece was etched a bit more after the bath temp climbed to around 230F and the piece slipped off the wire at the end of the stripping. It probably took a few minutes to fish it out;



I cleaned up one side of that piece up today for another trial and it didn't take much time to sand/buff the etching out.

The stripping process I'm using seems to work for me so I'll get back to sorting the anodizing. I've made some progress and will post more when I get back from a few days away.

Mike

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

mhc

Quote from: nelz on April 13, 2019, 02:55:10 PM
I was really enjoying your post 'til you got cut off. The shutdown is probably being caused by Windows auto-update. There are options to change it to manual restart as well as the option for the time of day to auto restart. Hope that helps!

Thanks Nelz but I think it's more than updates, it started a couple of weeks ago and seemed to be triggered by the screen saver - if I stayed active I was OK. The last few days it is getting even less stable and is 'encountering problems and needs to restart' almost continuously. I've tried to run reset but it crashes before it finishes, tried restoring once and it helped for a few days but the restore points aren't there now. I've tried sticking needles into my microsoft doll but that's not working either!

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

Alto Mare

Great thread Mike, but most of yours always are.
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
Forget about all the reasons why something may not work. You only need to find one good reason why it will.

mizmo67

This is awesome and I am sure that I will be pointing customers to this thread!
~Mo

Maureen Albertson :)
Scott's Bait & Tackle / Mystic Reel Parts (Formerly PennParts.com)
Contact Me Via Store Website Please!
Orders/Support# +1 (609) 488-4637 (parts ordering or troubleshooting)
customerservice@mysticparts.com

oc1

Thank you Mike.  This is getting more interesting all the time.
-steve

Frank

Thanks Mike. Very interesting thread!

Best,

Frank
Frank. Retired. Life long fishing and boating fanatic.

biggiesmalls

Awesome thread - deserves a sticky.
Drew

alantani

Quote from: biggiesmalls on April 14, 2019, 03:16:35 PM
Awesome thread - deserves a sticky.
Drew

Agreed.  This is also way past my pay grade. ;D
send me an email at alantani@yahoo.com for questions!

conchydong

#9
We did some anodizing and electroplating in high school chemistry class 41 years ago but I don't remember a darn thing about it.  ::)
I am going to follow this thread for sure.

David Hall

I knew this would be interesting and you have not disappointed.
Thank you for posting this.  I have a number of reels I hope to get cleaned up and re anodized one day in the not to distant future.

Rothmar2

Glad you have got around to sharing this with everyone Mike. Surprised that this hasn't been covered in detail before, but this is a great start. I am following this with interest. But I can see plenty more parcels on your door-step in the not too distant future! ;D :D

Tiddlerbasher

Mike - I'm following this with great interest. This is something I've always wanted to try.

thorhammer

Quote from: alantani on April 14, 2019, 05:46:21 PM
Quote from: biggiesmalls on April 14, 2019, 03:16:35 PM
Awesome thread - deserves a sticky.
Drew

Agreed.  This is also way past my pay grade. ;D


Agree. I'm a chemist and have thought about it but this looks like more hobby than I need to get into lol.


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.

David Hall

I venture to guess if he offered to do this for us, he would  have a hundred reels on his porch the first week.