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  #1  
Old 09-06-2018, 03:35 PM
Stockmanreef Stockmanreef is offline
 
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Default Alodine question

Do I have to use the Alumiprep-33 on a part prior to Alodining the part? Or can I just scottbrite, soap, water, acetone rinse?

Alodine is bad enough, but the Alumiprep actually sort of scares me. There is HF in the stuff. And low concentrations, which is worse than higher concentrations. HF absorbs through the skin and eats your bones. Low concentrations can't be felt on the skin.

Thanks
ken
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  #2  
Old 09-06-2018, 04:00 PM
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snopercod snopercod is online now
 
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Quote:
Originally Posted by Stockmanreef View Post
There is HF in the stuff.
Nah, it's Phosphoric acid. You really want to use it to get a chemically clean surface. Just be sure to flush off The Alumi-Prep with copious amounts of water. On the Space Shuttle, we tested for residual acid with litmus paper before applying the Alodyne.
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  #3  
Old 09-06-2018, 04:11 PM
Stockmanreef Stockmanreef is offline
 
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so can I just use phosphoric acid?
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  #4  
Old 09-06-2018, 06:54 PM
terrye terrye is offline
 
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Default Alodine question

I think there is also a detergent in Alumiprep 33. This is the stuff Henkel recommends for preparation of Alodine, and I don't think the chemicals in either one are worse than the other. Use the recommended protective equipment: goggles, proper rubber gloves and boots, respirator and protective clothing (I used a vinyl rain jacket and pants). Use good drinking water as a rinse.

Why compromise the preparation?
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  #5  
Old 09-06-2018, 07:23 PM
rv7charlie rv7charlie is offline
 
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Alodine can't do its job without the alumiprep (hint: 'prep') first. My understanding is that alodine is a 'conversion coating', which is effectively another term for a special kind of 'corrosion' that then protects the aluminum from further corrosion. It 'converts' a microscopic surface layer of un-oxidized aluminum to something that protects from further corrosion. It won't work on the corrosion that already exists on any aluminum that's been exposed to the atmosphere for more than a few hours, hence the need for alumiprep. The alumiprep etches away the existing corrosion, allowing the alodine to do its work. BTW, the alumiprep can't do *its* work if there's dirt/oil on the surface.

Again, just my understanding; I could be wrong.

Charlie

edit: Phosphoric acid is phosphoric acid, but that doesn't address concentration. If you can match the recommended concentration of diluted alumiprep, then you're good to go. But be aware that even undiluted alumiprep will eat right through concrete. Ask me how I know.

Last edited by rv7charlie : 09-06-2018 at 07:26 PM.
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  #6  
Old 09-06-2018, 08:46 PM
scsmith scsmith is offline
 
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Please just dispose of the used Alodine at a household hazardous waste site. Don't dump it down the drain or pour it on the ground. It contains hexavalent chromium, which is right up there with dioxin and plutonium in terms of toxicity and it permiates right into ground water or right into rivers and bays with discharge from water treatment plants.
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  #7  
Old 09-06-2018, 09:00 PM
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wirejock wirejock is offline
 
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Default Surface prep

Actually, my $.02, you can use other methods. I tried several. My standard for paint work is a good scrub with scotch rite and Bon Ami cleanser. I compared this method to Alumiprep and saw no noticeable difference in the conversion with the Alodine. That said, I actually used the Alumiprep as I was working through the Winter inside and the scrub method was impossible on the assembled fuse and wings in the garage.
As others have said, treat all chemicals as if they are all dangerous. Gloves, respirator, etc.
Dispose of chemicals and wash water properly. I scavenged all byproducts using a hole made sluice into a large storage bin. It went into a storage building till most of the water had evaporated then the rest poured into a stable container and taken to a haz mat disposal facility. Look at my blog for a tip on the sluice.
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  #8  
Old 09-06-2018, 10:19 PM
scsmith scsmith is offline
 
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Quote:
Originally Posted by wirejock View Post
Actually, my $.02, you can use other methods. I tried several. My standard for paint work is a good scrub with scotch rite and Bon Ami cleanser. I compared this method to Alumiprep and saw no noticeable difference in the conversion with the Alodine. That said, I actually used the Alumiprep as I was working through the Winter inside and the scrub method was impossible on the assembled fuse and wings in the garage.
As others have said, treat all chemicals as if they are all dangerous. Gloves, respirator, etc.
Dispose of chemicals and wash water properly. I scavenged all byproducts using a hole made sluice into a large storage bin. It went into a storage building till most of the water had evaporated then the rest poured into a stable container and taken to a haz mat disposal facility. Look at my blog for a tip on the sluice.
Bravo! I hope everyone follows your lead.
Good idea to let the water evaporate and create a concentrated, smaller volume. No point paying the hazmat folks to dispose of water.
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  #9  
Old 09-07-2018, 12:33 AM
Aluminum Aluminum is offline
 
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Quote:
Originally Posted by Stockmanreef View Post
so can I just use phosphoric acid?
Yes (or sulphuric or hydrochloric for that matter) but you also want to lift any grease so the acid will get to the oxide. Alumiprep contains a mix of solvents and detergents that helps with that. Or you can just use this stuff at half the price of Alumiprep, similar mix. Also good for etching your patio before paint.
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  #10  
Old 09-07-2018, 03:47 PM
Stockmanreef Stockmanreef is offline
 
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Thanks for the replies. Plutonium is a dead-right-now acute poison. Albeit not as toxic as Polonium. Hexavalent chromium is a dead-in-the-future sort of thing. Phosphoric acid is not a big deal--it is just that there is HF in Alumiprep-33. And if you want to scare yourself, then look up what HF will do to you if you get it on you. You should alway have calcium gluconate cream around when using anything with HF.

My biggest concern is getting rid of the waste and generating it in the first place. I am also getting tired of working with nasty stuff when I don't have to. I might start working with stuff at work that will cause blindness or kill you quickly if inhaled. Oh the joys of being a chemist.

I do like the Prep and Etch stuff. Only phosphoric acid.

What I want to do small parts--gear brackets and I thought that alodining the parts would be better than paint. I assume that most of the paint would scrape off when putting things together.

Maybe I will just find a place to anodize the parts.
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