Caswell Info Requested for Coating of new Tank

[EEL]

Hello All,

My local dealer just confirmed my new 05 S2R800 gas tank is in. Since its fresh out of the box, I'd like to coat it now before I have to deal with the expanding issues later on.

As a precursor I read some of the existing posts on how to coat a plastic tank. However I need to get some clarifications as some things are not settling well in my brain

1) It looks like one kit is more than enough to coat a tank. But I would prefer not to have excess. Someone please confirm that half of the mixture is adequate for getting a good coat.

2) I see how people are covering the bottom of the gas tank w/ plexi and the old O-Ring. But what about the gas cap? I'm assuming the gas cap doesn’t get insalled. What did everyone use to cover this up?

3) Most of the internals on the S2R are built into the flange at the bottom of the assembly. What about the vent and overflow lines? I don’t know if the internal hoses come pre-installed in the new tanks or what. How did whoever's done this before manage not to clog these up during coating process.

4) Peope have been saying that the caswell coat flows really slowly. Some people have mentioned thinning it to obtain better flow. What are you supposed to thin it with? How much did you add into the half mixture (mentioned above) to get the right consistency?

Thanks in advance.

[booger]

You can buy black rubber stoppers to fit your gashole at the Ace Hardware. Seeing the design of the fill tube, you may want to fit the puck to the inside rather than the outside & just carefully reach in & pull the plug from your gashole as the Caswell's curing.

Ask DP what he uses to thin, and his technique. I think he just uses regular paint thinner & patience. Any excess will ooze out while the tank's setting up.

I don't think you need to worry about the vent & overflow lines, examine the routing and you will see what I mean.

[Speeddog]

1) One kit is enough, and yes a half batch will be adequate.

2) A rubber stopper will work, but make sure it's a good fit, and tape it securely so it doesn't come out.

3) Vent and overflow lines are not an issue inside the tank.

4) An ounce of thinner works well.

These are the best info threads:
http://www.ducatimonsterforum.org/index.php?topic=46057.0
http://www.ducatimonsterforum.org/index.php?topic=43642.0

I recently did a tank, when I get some free time, I'll post up some more info.

[Goat_Herder]

I recently did a tank, when I get some free time, I'll post up some more info.

Please do.  I also got my brand new tank recently and will be coating it this winter.  Also, I've found a gas station with 100% gas (no ethnol) so my Duc will be drinking pure gas from now on.

[ducatiz]

1.  Do not use anything to thin the solution.  It's not a problem with metal tanks, but solvents WILL react with the nylon and can create a gas pocket.  If you do thin it, there is no guarantee this will happen, but it can.  The solution is thick, so do it in a warm LOW HUMIDITY environment.

2.  You will need to rough up the surface somewhat.  Use a hard plastic bristled brush, a small one and get as much of the inside as you can.  During the cure process, some of the components of the material come to the surface and stay there.  Roughing it breaks these up a bit and permits adherence.

3.  You can do more than one coat.  The first coat should not use any thinning, but the subsequent coats CAN.

4.  I can't stress how important temperature, humidity and motion are for this.  Don't do it when the temp is under 70 and if the humidity is over 25-30%.  You want the air a bit dry.  Nylon sucks up ambient moisture and the rate of absorption increases with temperature and humidity. 

Everything I know about doing this I have learned over the last 2 years of following the tank issue.  There is no problem with epoxy adhering to nylon, depending on the type and so far Caswell's has shown itself to adhere well.  There are others available for all of the polyamines (including Teflon).  The issue is really prep.  The instructions for Caswells are for a metal tank, don't follow them (i.e. thinning the solution and using nails in the tank)

PM me if you have additional questions.

[ducatiz]

One more thing, look on the underside of the tank for two things.

1.  The mould date
2.  The inspector's stamp

I am curious what dates you find.

(click thumbs)
Inspector stamp

Mould "clock" showing date -- number of dots missing is month, number in center is year.

[ducpainter]

I think the quality/compatibility of the reducer makes a difference on this 'Tiz.

If someone uses acetone/gasoline/paint thinner I can see a problem.

If you use a quality urethane or epoxy reducer I don't think gas pockets will be an issue.

[ducatiz]

I think the quality/compatibility of the reducer makes a difference on this 'Tiz.

If someone uses acetone/gasoline/paint thinner I can see a problem.

If you use a quality urethane or epoxy reducer I don't think gas pockets will be an issue.

the issue raised by the maker was the interaction of the reducer with the nylon itself.  i don't understand the specifics, but the rotomolding process includes some ingredients which outgass during the cure and form a layer on the surface.  the outside surface is hand finished, treated (sanded down and sealed) then primed for paint.  The inner surface is untouched, literally as is from the rotomold so the top layers of the nylon can have crap trapped.  if you want to see evidence of this, look at the surface and see the trapped air pockets.

one place i spoke to that does the tank coatings actually puts the tank in a jig that turns it for 24 hours so the coating is continually turned to get maximal coverage.  i don't know how they prep the tank.

corking the filler from the inside is a good idea imho.

the main area for coverage is the bottom of the tank more than the top.  some folks just capped the fuel pump opening and poured into the filler.  Some spots on the inside top may have been missed, but water precipitate in gasoline will sink to the bottom.

[ducpainter]

the issue raised by the maker was the interaction of the reducer with the nylon itself.  i don't understand the specifics, but the rotomolding process includes some ingredients which outgass during the cure and form a layer on the surface.  the outside surface is hand finished, treated (sanded down and sealed) then primed for paint.  The inner surface is untouched, literally as is from the rotomold so the top layers of the nylon can have crap trapped.  if you want to see evidence of this, look at the surface and see the trapped air pockets.

one place i spoke to that does the tank coatings actually puts the tank in a jig that turns it for 24 hours so the coating is continually turned to get maximal coverage.  i don't know how they prep the tank.

corking the filler from the inside is a good idea imho.

the main area for coverage is the bottom of the tank more than the top.  some folks just capped the fuel pump opening and poured into the filler.  Some spots on the inside top may have been missed, but water precipitate in gasoline will sink to the bottom.

I don't know what coating stays liquid for 24 hours. That jig would be great for acid etching tanks for POR.

[ducatiz]

I don't know what coating stays liquid for 24 hours. That jig would be great for acid etching tanks for POR.

I didn't mean they rotate it for 24 hours, that was bad editing.  they turn it until it is set which is just a couple of hours and then moving air for 24.

[thought]

Damn, this makes me worried as I just did the sf tank with a oz of thinner, I used lacquer/epoxy thinner, I didnt brush the inside of the tank to rough it up, and I only did one coat T.T

The only thing I would add is that the SF tank has a vent hole in the plastic by the gas cap that has to be cleared of epoxy for the breather hoses to work.  I didnt know this and I was getting a huge vacuum till it was cleared.  This also might be the be case with the new monsters... I was getting a vacuum sound with my 796 even though the hoses were ok.  The amt of vacuum wasnt as much as the SF though.

i'll add a link to this thread in the other caswell tips/tricks thread.

[EEL]

Ok so all this thinner talk got me a little bit worried. So I started doing some digging and research. Based on my conversation w/ Caswell, they recommend (as mentioned in other people's postings) lacquer thinner or xylene for a thinning agent.

I found a site that shows chemical resistance of different solvents to different materials; one of them being nylon. Link below for reference

http://www.coleparmer.com/Chemical-Resistance

I took an MSDS from google for a standard lacquer thinner and noticed its primarily a mix of hexane, toluene, acetone and methanol.

Checking compatibility w/ Nylon from the site above for each of these chemicals, it looks like most are decent. Methanol/ hexane have some issues w/ nylon and some of the others have ratings good to 72 degrees Fahrenheit. Looks like if you already used lacquer thinner, you're probably going to be OK.

That being said, xylene seems to be the way to go. Its got no compatibility issues with Nylon up to 120 degrees Fahrenheit.

Xylene meets Caswells requirements and requirements for nylon compatibility AND is pretty damn cheap.

Hope this helps others. This is probably the route I will end up going unless some of you pros out there see any problems with my logic. Comments are much appreciated.

Thanks

[ducatiz]

that's very useful

one additional point

get a wire brush and rough up the surfaces you can reach with it.  one of those smallish parts brushes or even a round type.

[ducpainter]

Ok so all this thinner talk got me a little bit worried. So I started doing some digging and research. Based on my conversation w/ Caswell, they recommend (as mentioned in other people's postings) lacquer thinner or xylene for a thinning agent.

I found a site that shows chemical resistance of different solvents to different materials; one of them being nylon. Link below for reference

http://www.coleparmer.com/Chemical-Resistance

I took an MSDS from google for a standard lacquer thinner and noticed its primarily a mix of hexane, toluene, acetone and methanol.

Checking compatibility w/ Nylon from the site above for each of these chemicals, it looks like most are decent. Methanol/ hexane have some issues w/ nylon and some of the others have ratings good to 72 degrees Fahrenheit. Looks like if you already used lacquer thinner, you're probably going to be OK.

That being said, xylene seems to be the way to go. Its got no compatibility issues with Nylon up to 120 degrees Fahrenheit.

Xylene meets Caswells requirements and requirements for nylon compatibility AND is pretty damn cheap.

Hope this helps others. This is probably the route I will end up going unless some of you pros out there see any problems with my logic. Comments are much appreciated.

Thanks

Good info...

I wasn't worried.

[jgrm1]

4.  I can't stress how important temperature, humidity and motion are for this.  Don't do it when the temp is under 70 and if the humidity is over 25-30%.  You want the air a bit dry.  Nylon sucks up ambient moisture and the rate of absorption increases with temperature and humidity.

How bad are the Caswells fumes?  To achieve these conditions, I would need to line the tank indoors this time of year.

-Jeff