TOPIC:

Hi! I may not even need tank liner but I really don't want to learn about it after painting.

I though installing it is a way to go (and cheap insurance). But reading another topic - I don't want to "uninstall it"

My question is:
1. Do you agree it's a cheap insurance or I should test for leaks first and do it only if it leaks? Hard to tell, leaks might appear after I sand through bubbles (not that many) and paint?

2. If doing it: Caswell or POR15?

There are many different point of view on the topic of tank cleaning and sealing.

I like to use phosphoric acid to derust (the same thing that Por-15 specifies.) It does a good job, is fast, doesn't need to be neutralized other than rinsing, and is pretty safe. As a bonus it's cheap, readily available, and it leaves the metal with a protective film that helps ward off (but not eliminate) flash rust when rinsing.

There are other good derusters like evaporust and the like. These are actually top of the heap in my opinion, but they are more expensive and slower.

Vinegar also works but it much slower. It's cheap and easy to dispose of so those are two good bonuses.

Using something strong like HCl works but is more risky. It needs to be neutralized and disposed of carefully. You can expect rapid flash rusting after rinsing too.

If the metal is solid and strong, with minimal thinning, and you are able to get the tank 100% free of rust I'd stop right there and call it done. If the metal is thinned and or springs a leak then I'd go the liner route.

Por-15 is thin like a thick paint and is easy to work with. This would be my first choice unless there is significant metal erosion. In that instance I'd go for Caswell's tank sealer. It's super thick and flows like cold honey. I recommend thinning it to the max allowable on the label. Because it's so thick though it helps reinforce thin metal, include sealing leaks. Tape over the leak area on the outside of the tank before sealing.

When sealing it's critical to flow the material all over the tank to get every inch of the surface covered. Then I'd go over it a second and third time. Then dump out the excess. There will still be extra material in the tank so keep turning it until the material kicks off and stops flowing. Only then can you rest and put the tank down.

It's a lot of work but done right a sealed tank will last for years.

[quote="Nessism"
If the metal is solid and strong, with minimal thinning, and you are able to get the tank 100% free of rust I'd stop right there and call it done

+1 on Nessism's advice. I picked up an 85 V65 Magna 9 years ago. The inside of the tank was slightly rusted, so I cleaned the rust out and did nothing more.
I still have that bike, and the rust has not returned. It is kept in a garage that never goes below freezing. Maybe with a bike left outdoors this would not be the case.

I have POR15 in my wifes KZ400 and time will tell on that liner, However, I have an SR650 tank with a failed caswell liner. Should be a fun process to remove.

Based these two I would go with the POR15 if a liner is needed.

None.

Kidkawie is correct - none is best. Ed

TheWhiteDevil wrote: I have an SR650 tank with a failed Caswell liner. Should be a fun process to remove.

Based these two I would go with the POR15 if a liner is needed.

Hey White Chopper Devil? Can you tell me about the bad Caswell experience? I put it in a set of 1970 OEM Harley fat bob tanks.
I did not paint them yet. I coated them last year! All my projects take time! I never finish because I start another one and work on 10 projects at the same time
I did prep it well, even though Caswell says to leave some bad? For their product to stick. I did it all! acid, black cat aggressive media blast in the blast cabinet, dry wall screws with a lacquer thinner wash. Did it in summer, baked in the sun! I loved the stuff. But nothing has been in it yet.
Thanks.

z1kzonly wrote: I did prep it well, even though Caswell says to leave some bad? For their product to stick.

I call BS on Caswell for that. Por-15 suggests the same but don't believe it. Remove ALL the rust before sealing. And the only reason to seal is if the metal thins out and/or you spring leaks while derusting.

Caswell is my weapon of choice. I have never heard of a Caswell failure before this. Hell, I spilled some on my garage floor and it is going to have to be chiseled off.

+1 on Caswell. I used it several years ago on my XT225 that had pinhole leaks in several spots. Its more than a coating, its a 2 part epoxy. I believe with a second application, I could peel the metal away and have an epoxy tank.

Nessism wrote: I like to use phosphoric acid to derust (the same thing that Por-15 specifies.) It does a good job, is fast, doesn't need to be neutralized other than rinsing, and is pretty safe. As a bonus it's cheap, readily available, and it leaves the metal with a protective film that helps ward off (but not eliminate) flash rust when rinsing.

And, it's reusable - at least to the point where is doesn't do anything anymore.

cb900f wrote:

Nessism wrote: I like to use phosphoric acid to derust (the same thing that Por-15 specifies.) It does a good job, is fast, doesn't need to be neutralized other than rinsing, and is pretty safe. As a bonus it's cheap, readily available, and it leaves the metal with a protective film that helps ward off (but not eliminate) flash rust when rinsing.

And, it's reusable - at least to the point where is doesn't do anything anymore.

(in the USA at Home Depot) Kleen Strip Etch and Prep is phosphoric acid. I've got a gallon ($15) that's been used dozens of times and it's still potent. Sludge develops on the bottom of the jug so I short pour when using it. It started out green and now it's clearish, but it still works great. Amazing stuff. Recycle again and again.