I have heard you guys use the term etching. I was wondering what the best chemical to use for etching was, as well as the safest (inhalation wise).
Is this the same as putting acetone on your work ? or is etching the use of a more potent chemical?
I have heard of people cleaning with muriatic acid. and I have found an unopened jug of it here in the shop, I havent messed with it yet because I dont know how dangerous the fumes are, as well as skin contact. IS muriatic acid good to use on aluminum?
What do you guys suggest ?
I've never etched AL. But I do clean all weld areas before welding with a SS brush and I never really have any problems welding it. Only problems I endure are when it's old oil soaked garbage and I have to burn the impurities out of it :( Thats a very smoky bad time
we use ethanol at uni, and then blow the work piece with hot dry air. I assume its the same as putting acetone on your work.
Pascal.
I don't know about HCl as an etchant but it definitely will do bad things to skin, and really bad things to eyes (instantly). http://www.chem.tamu.edu/class/majors/msdsfiles/msdshcl.htm
Here's an msds.
Bill
wow. I think I might stay away from the muriatic Acid.
Thanks
I hadn't intended to be too pessimistic here, just to suggest care. Rubber or plastic gloves and apron, face shield, running water nearby, and good ventilation while handling the concentrated material. (others feel free to add to this list). After dilution the material is much less dangerous. This applies to all acids and strong bases (like sodium hydroxide (lye)). Add acid to the dilutant, not the other way around. Add small quantities at a time.
Bill
AWS welding handbook volume 3 part 1 has a table detailing chemical treatments for oxide removal prior to welding or brazing aluminium.
Sodium hydroxide (caustic soda) NaoH (50 grams) in 1L of water at a temperature of 60 - 71 C, immesre in a mild steel container for 10 - 60msecs rinse in cold water. Followed by Nitric acid equal parts of 68% HNO3 and water at room temperature immerse in a stainless container for 30 seconds. Rinse in cold water. Rinse in hot water and dry.
Others include Sulphuric chromic acid phosphoric chromic, sulphuric acid and ferrious sulphate.
I'm not involved in Al welding but I would guess that your local welding store or distributor may be able to put you onto a proprietary etchant to save you mixing this nasty stuff together.
Etching is more potent than acetone which is simply a degreasing agent.
Two links I found...
http://www.lincolnelectric.com/knowledge/articles/content/tigalum.asp
http://www.alu-info.dk/Html/alulib/modul/A00299.htm
very informative, thank you sir!
If you are looking for an etchant to see the pass sequence or measure penetration you can use Drano. I wouldn't use it for any microscope work, but it will do just fine to check the penetration on a weld.
-Sean
i am just trying to clean the area 100% before welding. is this an effective way to clean? or is it just used as a marker for checking penetration?
I think Sean is thinking about macroetching a weld specimen. This is done to make the individual beads visible for VT during procedure or welder qualification. It is different that etching to clean the metal before welding.
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