Tank Sealing

[skiracer]

I know there has been a lot of tank in the past about sealing fiberglass tanks.  I tried to search for the name of the sealer that is being used, without finding it.  What works?  Thanks, James

[Tim McKinney]

Most guys recommend Por-15. I have used Casswell with good luck but some on the site have had issues with alky related fuels affecting it?

OLD BIKES RULE!!!

[Mark Liston]

James,
Based on careful reading of members input, previous experience and a  lining of my 70 steel tank last week I would highly recommend a product by Caswell. See their webpage "caswellplating.com".
Product no. is GTS1750. Product shipped is enough to do two normal size bike tanks. Cost is $39.99 and shipping to my residence in NW Indiana was $13.50 or so for a total of $53.50.

Mark Liston

[Gordon Brennan]

Here's some information provided by Michael Winter on the subject.

I usually pick up my POR-15 CLEAR at automotive swap meets, but there are sources on-line that sell it as well. It seems that the amount of Alchohol in the gas which is ever increasing is the reason for the problems with the tanks. I have had a tank that never had any problems start to exhibit bubbling of the original gel-coat, but I don't drain my tanks usually.
Here are the directions that I have provided some other people inquiring on the application for coating the inside of a fiberglass tank.

I first wash out the tanks 2-3 times with Lacquer thinner to remove as much traces of oil as possible, rinsing them for about 2-3 minutes each time and after the last rinse, I wash it again with MEK, (Methel Ethel Keytone), or Acetone should also work, to remove any remaining traces of moisture. MEK is very toxic, so avoid breathing the fumes or allowing skin to come in contact with it. Acetone can be use in place of MEK, but doesn't have quite the drying capability as MEK. Once the final rinse is complete, the tank will be stickly on the inside due to the thinner starting to break down the fiberglass resin. Care should be taken not to over do it and collapse the tank.
The POR-15 product I use is POR-15 CLEAR and requires no metal prep. I do use the POR-15 brand thinner and thin the mixture about 15-20% to aid in ease of swishing it around in the tank. The POR-15 websites states that is should only be thinned 5%, but thinning it a little more only slows down the time it takes to initially set up. POR-15 should not be used with any other brand thinner according to them.
I remove the petcocks and insert temporary plugs or rolled up white duct tape in the holes which can be easily removed and reinstalled before the POR-15 CLEAR sets up. To do one tank I used 1/2 of one pint plus the thinner and once poured into the tank, I tape over the filler neck and rotate the tank several times and then drain it back into a separate container through one of the petcocks, which requires rotating the tank several more times to get the majority of it out. Once sufficiently drained, I remove the other petcock plug and the tape from the filler neck and position the tank so that any remaining POR-15 CLEAR will pool in the lower rear area of the tank, which is prone to wearing on the frame cushions and often leaking.
Periodically check for drips coming out of the petcocks and wipe away any drips to avoid plugging of the petcock holes and requiring inserting a drill bit and cleaning them out before the POR-15 fully sets up. After about an hour check the tape removed from the filler neck and once it becomes tacky, repeat the whole process again 2-3 more times, and when finished let the tank set open for a couple of days and it will be ready for use.
BTW, The fiberglass that I coated in POR-15 CLEAR and soaked in Lacquer thinner never did become soft or sticky.
A pint of POR-15 CLEAR thinned 15-20% should be enough to coat 3-4 tanks if done at the same time. Once removed from the original can, do not pour it back in with the unused POR-15 CLEAR or it will cause it the unused POR-15 CLEAR to prematurely set up. Seal the lid of the unused POR-15 CLEAR with some wax paper between the lid and the can immediately after removal of the amount to wish to use, and store it in a cool place for later use, but if any gets in the groove of the can lid, you will probably have to puncture the can to get the lid off.
Preparation for coating the exterior of a tank only requires sanding into the Gel Coat and cleaning the prepared surface with Lacquer thinner. The POR-15 clear is best applied with a brush, as thinning it enough to use a spray gun will usually cause tiny bubbles in the coating, and will require finishing with a brush anyway. Once the POR-15 Clear becomes tacky, repeat the coating process at least 2 more times. POR-15 instructions state that while still tacky your favorite primer/prep coating should be applied to bond with the POR-15 Clear to allow you to later sand the primer and apply paint. POR-15 is a very hard coating, but it can be sanded and painted later if you like hard work hand sanding for a smooth finish.

[joe novak]

Hello,  Thank you for the all the information on tank sealing.  I just want you to know that this posting is worthy of printing so that I may file it in my Penton information.   Remember that the reasons for sealing a steel tank may differ than those of a fiberglass tank, though.   Joe

[skiracer]

Thanks guys!  That is some very informative information.  I appreciate the time taken to write such detailed instructions.  Have a great weekend!  James

[454MRW]

Regarding POR-15 Clear on Metal tanks, I would recommend using Metal-Ready to etch and prepare the tank, but only on a metal tank, not a fiberglass one. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S