[helfires688]

Hello all,

I've got a project where I need to etch some aluminum TIG'ed parts that failed a pressure test, and I saw that Jody recommends Easy Off oven cleaner for etching aluminum, has anyone else used this that could comment on the process and provide any tips/tricks to get a good polish and etch on aluminum?


Thanks!

[Franz©]

Aluminum is a funny animal, it ain't all the same alloy, and different alloys react differently to acids and bases.

I'm presuming your goal is to take a slice of the failed weldment, polish it up and then employ an etchant to display the opening that is your leak.

While you're using ordinary sandpaper in diminishing grades of abrasion to shine the slice up, grab that pack of Ketchup out of the desk drawer, glove compartment or whereever you stash them, and put a few drops on the piece you're not sanding down. Vinegar also works on some alloys along with Phosphoric acid which will dissolve some alloys.
If your alloy is not reacting to acids, try some base ranging from baking soda to drain cleaner such as Draino.

A drop of battery acid will also display cracks quite well on some alloys, but that is becoming more difficult to get with sealed batterys.

[helfires688]

Franz,

The part in question is a 6XXX series aluminum, but I will also potentially etch some 5XXX series as well. Do you know if acids will work on those?


Thanks!

[Franz©]

Low concentration Phosphoric Acid (4 to 10%) in water is universally used to etch aluminum to create a grip structure for paint and coating adhesion in a tank setup.

The key to what you're trying to accomplish is time on target.

Try ketchup, vinegar and if you have to try phosphoric containing toilet cleaner and concrete floor cleaner from Homer Desperate or Blows. Once you get the right combination to react you'll need to work out the time of exposure. It's sort of like the old process of black and white photo developing in trays.

You also need to remember your polishing can hide the void by smearing aluminum over the crack..

This may help you and save me typing.
http://www.esabna.com/us/en/education/b ... -welds.cfm

More information.
https://goodson.com/blogs/goodson-gazet ... -detection

[helfires688]

Thanks Franz! I'll give those a try first and report back.

[helfires688]

I ended up getting the easy off that Jody recommends and it works amazingly well. The part was machined, then sanded with 1200 grit wet/dry sand paper, cleaned with acetone, and then sprayed with easy off. I applied the easy off 3 times, letting it sit for about 2-3 minutes each time and applied a bit of heat with a propane torch. After the third time, I dabbed the area with a wet paper towel to remove the easy off, and then rinsed the part. The results were amazing, I really wish I could post pictures, the weld area shows up as bright metal and the parent metal stays a darker grey. It should be noted that the fresh scent seems to work faster and can be heated where the lemon scent cannot and is slower.

[helfires688]

For reference, this is what I used: https://www.walmart.com/ip/Easy-Off-Hea ... 45&veh=sem