Oh my. Strange blisters all over the fuel tank finish.

[Micha]

Good evening,
I treated the fuel tank with phosphoric acid, just as Snowbum describes in his very interesting article
(https://bmwmotorcycletech.info/fuelmiscl.htm).
Indeed, the inside of the tank got a nice gray and etched finish, but from the outside the tank got a lot of blisters under the paint finish, not only in disaster-prone areas (braze seams, etc.), but also in smooth straight areas that I do not know what and how it was caused. Is the metal really in such a bad condition that its sides are so thin and the acid has passed through it to the outside? I find it hard to believe, because I knock on the metal walls, and looked inside with a flashlight. I guess if the metal walls were rotten, I would see it.
well, I really got messed up here and also got one step closer to a risky purchasing of a new fuel tank for all the risks involved.
What do you think happened here?
What do you think regarding the phenomena? Would gasoline also penetrate the tank's side as the acid did?
How can I email Mr. Snowbum?
I must point out that I want to consult with him and not (God forbid) complain!
I learned a lot from the advice he gave with his great generosity and from the vast amount of information he has accumulated and greatly appreciates it.
I would love to hear what he thinks I should do and why all this could have happened, and of course your opinion!
Thank you and take care

[schrader7032]

Snowbum has a link at the bottom of the tech page to email him.

I'm no chemist, but it does appear that either the fumes of the acid penetrated the metal or they just created a cloud around tank during the process that resulted in this.

[cbclemmens]

It is more likely that the phosphoric acid treatment caused an exothermic reaction in the tank and that the paint blistered due to the heat.

[Micha]

Thanks both of you.
I could not find that email - can you pls direct me? There is none at the bottom of the pages.

Regarding the heat, well the instructions say to use the solution with dilution in very hot water.
The solution was in the fuel tank for 5 hours and was performed in the open air.
But it could very well be that the hot water caused the outer bubbles on the paint.

[schrader7032]

There is a line near the very bottom of the page that says "Email: click". I suspect that it will either bring up your email program or it will start a page where you write your questions and it sends that to him...not quite an email, but close to it.

[weh8127]

Take heart, man. If the tank Is spoiled it wasn't likely a good tank in the first place. If the tank is solid, you're better off repainting than buying a new tank, anyway. Take the tank to a radiator shop and have them put 5 or 7 psi ( English measure) in it and submerge in their tank to check for leaks. If its good they can probably re-coat the interior as well. Then have it painted.

[Micha]

Thanks guys.