ProSeal Dance HOBBS 314.5 hrs

Yesterday was a very productive day as I logged 5 hrs in the shop before heading off to the Great American Beer Festival with my little sis and some of her friends. I finally introduced myself to ProSeal...well, thats not entirely true as I used it on my rudder trailing edge. However, when I did the trailing edge I used a cartridge that mixed inside so it wasnt as messy. This was the first time I had to weigh it out and actually mix it in a cup.To those who dont know, ProSeal is a two part polysulfide that is commonly used to seal fuel tanks. Its dark gray sticky stuff. There are plenty of horror stories out there that builders have regarding this evil concoction.

So the first step in the process is riveting and sealing the tank stiffeners, the fuel cap access hole and the fuel drain. Its a good first introduction to the process without getting overwhelmed as this is the easiest of the tasks to come. All in all, my general thoughts are it isnt that bad. Check back when I finish however, rumor has it, it only gets worse from here.

For this batch I did 60 grams (white) to 6 grams (black) (10:1 mix ratio) and quite honestly it was a perfect amount for this task. I used every drop I had and didnt feel like I was shorted on anything. Of course, this was my with my application 'style'...other builders may use more or less. I'm not sure but I think I was on the light side with my application. Most builders put much more on the first tank than the second so I am keeping that in mind as I work. I dont believe quantity is as important as quality and paying attention to the areas that really need it. We'll see if I'm successful with this strategy when I check for leaks at the end.

Some random thoughts and observations after day one...

1. Anticipate that you will need to do something you didnt expect...like drill out a bad rivet, have those tools ready...I didnt. It got a little stressful since the clock was ticking.
2. The shop was at a nice 72 degs, I had a good 90 mins working time with my batch. If its warmer, expect to have less time.
3. Cover anything and everything you can to keep it clean...within reason
4. Cleanup is not that bad with MEK...even 24 hrs after the fact
5. Wear two pair of gloves, it makes it easier to swap out clean ones (Thanks to Sean Blair for that tip)
6. Try to be neat, but in the end, this is about functionality...its not a craftmanship contest. Nobody will ever see the inside of your tanks so dont stress about how it looks too much.
7. Be smart about your application of ProSeal...what exactly am I trying to do? Where is it going to leak (rivet holes)? Focus on that first, the 'extra' stuff (mating surfaces) is just insurance.
8. Do a good layout of tools that you'll need before starting...be organized.
9. Do a 'dry run' on how you will rivet parts and tools for the job before mixing the ProSeal...squeezer? rivet gun? is there enough room? etc, this will cut down on stress. Have a plan. Just like flying...think ahead and be prepared.
10. ProSeal is the consistency of fresh really sticky taffy, if you havent experienced it.
11. I didnt need rivet tape when I backriveted...the ProSeal held the rivets in place pretty good.
12. Use the stickiness of the ProSeal to your advantage if you can. I got to the point where I could 'stick' a rivet to the end of my finger and then insert in the hole.
13. I didnt apply ProSeal directly to the rivets, but dabbed it in the hole before inserting the rivet. Either way would work.

Here are some pics from day one of the ProSeal dance...

Maybe a bit of overkill, but I used a sharpie to lay out my areas for scotchbrite..this is where I will scuff the alclad (dont forget to do both surfaces) for good adhesion of the ProSeal. I dont want to go crazy with this scuffing because once you take off that alclad it has no corrosion protection. I havent heard of tanks having interior corrosion problems but I still will be conscientious of this as I work.

After scuffing...then clean with MEK to complete the surface prep

Apply electrical tape to keep these areas clear of ProSeal...this is where the ribs reside. The tape works great and is the perfect width.

Fuel drain...same layout idea for prep. Although the drain will sit on the outer surface of the skin.

This was a good tip that I picked up from other builders. Cut down the bristles on these brushes to use for application. You have to watch for bristles coming loose, but otherwise it works great. Quite honestly, I couldnt find popsicle sticks and used these exclusively. Both would be nice however...I need to find some.

Protect your stuff from the goop. I used press'n'seal cling wrap to cover my scale and chemical bottles. Here is a shot of my digital scale I bought at Harbor Freight...$20. Worked great. Dont forget to tare the scale for your mixing cup.

Pre-soaking the rivets in MEK to make sure all chemicals/coatings/dirt/oil are removed so you get good ProSeal adhesion.

Interior view of the fuel drain all sealed up. A little overkill here since the rivets are the only real source of leaks. But hey, a little extra wont kill ya either....but certainly not needed.

Kinda ugly...but it should do the job.

Here is the inside of the fuel cap access hole (the 'money' hole). I really paid a lot of attention to this area to make sure I sealed it up good.

A shot of the finished product...a good start.