Polysulfide sealant resistance to Lacquer Thinner

[BJohnson]

Question:

Is the polysulfide sealant soluable in lacquer thinner, or do I get to rebuild my tanks?

After procrastinating closing out my fuel tanks for 5 years, I finally closed them out and leak tested with a manometer and soap bubbles to find that they are leak free. However, as I went to prep the baffle and end ribs for primer, I found that stray bits of sealant could be removed with a lacquer thinner dampened wipe.

When I closed out the tanks, I used a pre-packaged Semco cartridge, that only required injecting the hardener and mixing. But when I built the tanks I used a digital scale and recommended weight ratios. Comparing the two visually, my hand mixed material is several shades lighter gray, but still a dark gray, than the Semco mixed material, which in nearly black. So now I am concerned that the hand mixed material was not mixed to the correct proportions, leaving the sealant vulnerable to the avgas.

 

[Daver]

tank sealant

I was always led to believe the this sealant, once cured, is impervious to just about everything.

My tanks have been assembled for about 3 years now and in service with fuel in them for almost a year.

No leaks yet.

I was careful during assembly to clean everything I wanted the pro seal to stick to with MEK; all surfaces and rivets. I scuffed up the AL pretty good too.

Knocking on wood...

Dave
flying -9A

 

[sprucemoose]

Bruce,

If you used the stuff from Vans, it does cure to a medium dark grey color, not pitch black. Don't worry about it.

 

[rzbill]

Laquer Thinner will clean up Vans proseal offering for many moons after cure. Can't say I tried 5 years but have done months.

 

[chevytoo]

I have used proseal for more than 30 years. We never measured for mixing, just mixed until the colour was about right. It always cured. Sometimes in a week and sometimes it took a month. When it is cured there is no solvent that I am aware of that touches it. We used paint remover and then scotch bright and MEK. I see there are plastic cutters available to clean up old proseal. I have not used them but they look interesting.

Ray

 

[RV6_flyer]

I tried to remove cured ProSeal with a number of different paint strippers. Of the ones I tried, only about 1 in 6 softened it up.

Very few things will remove it once cured but it can be removed with the right product if you can find it.

 

[DanH]

Question: Is the polysulfide sealant soluable in lacquer thinner, or do I get to rebuild my tanks?

I've had cured samples submerged in a 50/50 mix of lacquer thinner and MEK for over a year. Definitely not soluble....even with improper mix ratios.

 

[rzbill]

Hmmm.. Curiouser and curiouser

With that data from the Wizard of Wetumpka, I can only assume that my experience might have come from a cold shop. I lived in PA during the tank building period. It took a LONG time (many days) before my proseal would not show a fingerprint and Laquer Thinner would visably assist removal of drips for weeks afterwards. I am 100% confident that my ratios and mixing were spot on.

 

[BJohnson]

Thanks but still curious

OK, thanks for the advice. I am sure the mixing ratio was what was recommended. The material stiffened up within a day and was tack free soon after. So I will move on and celebrate not having any leaks!

But, I am still puzzled by the ability to clean up the sealant with lacquer thinner. It did not wash away, but with scrubbing the material would wipe away eventually, from the top of the material, down to the metal. It was not an adhesion failure since the last material to rub away was the material closest to the metal.

Curious about the 1 yr immersion test from Dan. Did the material seem any softer than a non-immersed specimen?

Another thing that got me scratching my head was during the manometer testing of the leaks. It was so sensitive to temperature that putting my hand on the tank would rise the water level 2 mm. Over a 1 degree temp swing, water levels would change between .5 and .8 inches (never measured it). But no matter haw many times I tried collaborating that result with PV=nRT, the calculations would not indicate that high a level of change. Another mystery left behind to get this thing flying.

 

[John Tierney]

Proseal thinner

I've been told that the Proseal mixure can be thinned with toluene, and I think the primary ingredient in Lacquer Thinner is toluene. Has anyone tried this? I have a small leak that could probably be solved with runny proseal.