Phosphoric Acid for rust cleaning / inhibitor: Mixture and Procedure

[tmassey]

Because, according to my training in O2-cleaning tanks, the oxygen-cleaning process was supposed to be the very last step.

You are correct: the O2 cleaning *process* is supposed to be the very last step. Detergent by itself does not equal o2-clean. Nor does O2-clean equal a single step. And the detergent step is never the last step: you have at least rinse and dry. So nothing that anyone described violates that principle at all.

Chill, bro.

Thanks, I’m good. Bro.

 

[rjack321]

I’m trying to avoid going the tumbler route at home. I think I'm gonna give this method a try. You just slosh some cleaning solution around in the tank and then do the same with the phosphoric acid solution?

For both the simple green and acid steps (when I use acid) I use my tumbler just no or very little ceramic media. You dont want the acid used up reacting with only part of the tank walls. All my tanks are pretty pristine inside though. So I only use media in extremis or if I get a new-to-me tank that needs extra love inside due to past abuse. I have acid washed (rarely) some of my tanks that ended up with a spot or two of rust on the bottom from a water droplet that wasn't blown out of the valve.

 

[happy-diver]

What's this tumbling isn't that what circus performers do, I call it rumbling but we don't talk about rumbling

Do youse blow like it blows you over as you're hooked directly to a tank without regulator so you really blow

 

[Johnoly]

Bumping & adding to a VERY GOOD thread with my picts and tips. I had some flash rust in a steel 13 pony bottle. No pits but I tried a quick steel wire whip in a drill without much success. I had long ago saved this @tmassey phosphoric acid thread to use when I was ready to do it. The mixing instructions and safety tips were easy to follow. I added an old disposable full face Covid shield for possible splashes just in case. In his table is listed the mixture for 'Heavy Scale” and I used that mix ratio. Here is a side by side picture of the 'before & after treatment' inside the tank for reference.

Just a couple of my tips to add:

I put a worm drive hose clamp with a swivel clip tightened down to the base of my tank so I could hang it upside-down from a rope over a ceiling rafter board in my shed. This allowed me to blow in the tube of scuba tank dry air to almost instantly dry the inside of the tank. It was at an angle but actually made it easier to blow the side walls of the tank. There's no way to easily hold a hot tank while moving the air tube around the sides.

My hot water rinse temperature was 180 degrees cause I used to watch Tim the Toolman Taylor and more is usually better, lol. Worked great, but like Tmassey said wear thick neoprene/leather gloves cause that tank is too hot to hold. YMMV.

Lastly here is a picture of my dirty phosphoric water mix that came out of my tank. As said in the instructions, it went in clear but came out a darker cloudy color.Don't expect a mud color.

Finally, a big thanks to @tmassey for his long detailed writeup and easy to follow mixture. It worked perfectly for me, I'm pleased with the results and not a lot of time.

 

[tmassey]

Not my most liked post, but one that definitely draws enthusiastic response from those who try it.

If I had a nickel for every time @Tracy has texted me about him using the process, I’d have two nickels. Which isn’t a lot, but it’s weird that it’s happened twice.

I used it a couple of months ago on four really-rusted LP72 tanks. I had to use two batches of acid on those puppies. Not only were they rusty, but they smelled bad. For those, the acid alone wasn’t enough: I ended up having to whip those tanks as well. But a good long time with the acid – like several days, and a couple of times with the whip did get them sparkling clean. @coleman.jamie owes me for that: two of them were his. (Actually, he doesn’t: not only did he pay for me to do it, but he also gifted me a couple of replica Dacor stickers to put on the tank to match the ones that were on there originally. I ended up keeping the originals on because I like the “survivor” feel, but his tanks ended up looking really, really nice when they were done.)

The irony is: it isn’t even my process. I just collected the various bits of wisdom floating around and gave them a good mathematical shake up.

I will say this: now that I’ve gained some experience with the process, I think I would always use one level of mix stronger than what the label suggests. I think because the chemistry was so very wrong from the original source material that people were using stronger mixes than the formula actually described. The weaker mixes will get the job done, it just takes a while. I haven’t seen any downside from using a little bit stronger mix. I personally haven’t used anything ridiculous, but up-thread some have commented that they use hardware-store concrete etch straight from the bottle. I think if you use even a little bit of common sense, it’s hard to screw this up.

 

[Tracy]

Not my most liked post, but one that definitely draws enthusiastic response from those who try it.

If I had a nickel for every time @Tracy has texted me about him using the process, I’d have two nickels. Which isn’t a lot, but it’s weird that it’s happened twice.

I used it a couple of months ago on four really-rusted LP72 tanks. I had to use two batches of acid on those puppies. Not only were they rusty, but they smelled bad. For those, the acid alone wasn’t enough: I ended up having to whip those tanks as well. But a good long time with the acid – like several days, and a couple of times with the whip did get them sparkling clean. @coleman.jamie owes me for that: two of them were his. (Actually, he doesn’t: not only did he pay for me to do it, but he also gifted me a couple of replica Dacor stickers to put on the tank to match the ones that were on there originally. I ended up keeping the originals on because I like the “survivor” feel, but his tanks ended up looking really, really nice when they were done.)

The irony is: it isn’t even my process. I just collected the various bits of wisdom floating around and gave them a good mathematical shake up.

I will say this: now that I’ve gained some experience with the process, I think I would always use one level of mix stronger than what the label suggests. I think because the chemistry was so very wrong from the original source material that people were using stronger mixes than the formula actually described. The weaker mixes will get the job done, it just takes a while. I haven’t seen any downside from using a little bit stronger mix. I personally haven’t used anything ridiculous, but up-thread some have commented that they use hardware-store concrete etch straight from the bottle. I think if you use even a little bit of common sense, it’s hard to screw this up.

I mixed up 2 gallons at 7oz 85% per gallon. I believe you had that marked at 5%. Whatever it is, it works great. I have done over 70 tanks with those two gallons so far and it is still eating. I quickly learned exhaust fans and makeup air are very important in this process, but it is fast and does a nice job.