| Author | Message | ||
     Greg_e |
I know there are a few people making things on here, and I just stumbled upon a different way to Anodize aluminum that is a little safer than using sulphuric acid for the home machinists. It uses a sulfur salt which is far less dangerous and available for swimming pool pH modification. Haven't tried this yet, but it won't take long before I gather the materials. http://www.observationsblog.com/sciencetechnologye xperiments/anodizing-and-dying-aluminum-without-ba ttery-acid https://www.youtube.com/watch?v=7jFN3l_mrKk If you try this, let me know how it works, probably take me a couple weeks to get going. | ||
| Damnut |
Watching with excitement. Let me know how that works out. | ||
| Greg_e |
Went to Lowes and got a bottle of pH down for the sodium bisulfate. Went looking for the lye to clean the aluminum and found nothing as it is all out of stock. Thinking it was out because it is used in some illegal drug, I looked it up and lye is somehow used to make methamphetamine. I wonder what else we can use to clean and etch the aluminum that won't set off alarms. | ||
| Greg_e |
Looks like sodium carbonate might work, Clorox pH up product for pools. Knew I should have picked up a container of this today. Can also be made by cooking baking soda. I did also get some Rit dye in black and in red, just to play around. | ||
| Torquehd |
random side note - sodium carbonate ("washing soda") is added to molten aluminum to degas it prior to casting. I googled "etch aluminum with vinegar" and this video came up https://www.youtube.com/watch?v=HNZZ8RJfzNQ There are some articles on boiling a solution of vinegar and water to remove oxidation from aluminum pots and pans. That may be a possibility. | ||
| Greg_e |
The vinegar works, but is normally very slow. Acetic acid also works, but is again pretty slow unless you are buying the lab grade "pure" stuff. Nitric acid works really well and I think it also keeps the smooth surface on polished pieces, but that's getting into that less safe area again. | ||
| Greg_e |
First test... Huge success! The Clorox pH up is pretty weak compared to lye, let it soak a good long time. Probably works really well with polished objects as it didn't really give the matte etched finish that lye gives. In other words, clean up your pieces because this will not hide any tool marks! I used some sodium carbonate with hot tap water, sorry didn't measure it. The Clorox pH down worked pretty damn well. Again, no measurements, just kind of added a bunch to some tap water (better to use de-ionized water). After 4 hours at 15 volts the piece of 6061 pretty much stopped reacting on it's own. This normally doesn't happen with sulfuric acid as it is a reversible process, the acid keeps dissolving the aluminum oxide. Here's a short video showing the process at the beginning of this step. https://www.youtube.com/watch?v=SmFxHzM0U6g After I rinsed in hot water (a lot) and then mixed up some really strong RIT black dye. Soaked the part in it for a while, then rinsed in cold water. At this point it looked kind of purplish-brown, but the dye was even which proves the anodize was even. Then put it over a pot of boiling water to let the steam seal the anodize "peaks". After cooling and wiping with a paper towel, it is really a nice black. Only two little spots of copper color, must have pulled some copper out of the alloy. Very pleased overall and certainly going to become part of my standard finishing. Here's a short video of the steaming: https://www.youtube.com/watch?v=gEa-yFnZHbU Sorry, no picture of the finished product, since Photobucket has changed I haven't set up a new picture sharing site yet. I'll have to buy some of the good dyes from Caswell, but the RIT worked. (Message edited by greg_e on November 24, 2017) | ||
| Zac4mac |
I'm watching | ||
| Greg_e |
Need to pull camera mounts off my race bike and finish cutting them, then clean up with Scotchbrite rotary pads and do all this again. Got a handful of other parts that need to be done too. One thing I need to figure out is how to chill the anodize solution. This should give similar results to cold/hard anodize. It did get a little warm at times. Forgot to mention that I was just using a cheap walwart power supply, just had it in a drawer and decided it would be good enough for now. A lot of people convert an old PC power supply to use for this, lots of amps for really big parts. Not sure if the oxide layer suffers from too much current like it does with acid anodize, I didn't think to measure my current to see if it was drawing all the supply could give. By the temperature of the supply, I'm guessing it was drawing under an amp (about half the rated value on the supply). The supply never really got hot. |
