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Proseal Curing Question

S

Stockmanreef

Well Known Member
I live in Michigan, its cold, and I want to build my tanks. Well, I mixed up a small batch of proseal. It was really hard to mix and to weigh out. The material was not flowable at all. It is about 40 F in my garage and only turn up the heat when I am working.

1. I think that I figured out that I have to keep the unmixed proseal in the house where it is warm. Good idea? How warm should the material be in order to get it easier to work with? I have seen posts where they heat it up to 80F prior to mixing.

2. Should I bring in the parts to have them at room temp prior to applying the sealant?

3. Should I bring the parts inside to get them to cure?

4. should I just move on to the ailerons and flaps, then wait until warmer weather to build the tanks?

Thanks
ken
 
I think the proseal and parts should be at room temp (70 or more) before you apply it. That way, it'll flow better into any gaps, and will squeeze out better when you rivet the assembly. You'll also have an easier time applying a good filet in areas which get that treatment.

At low temperatures, you will see extended curing time. Days, maybe weeks. It won't hurt a thing, but every time you walk past and put a thumbnail into the proseal, you'll wonder "Is this stuff gonna cure?".

The answer is yes.
 
I did my tanks about 1 month ago. Temps when garage unheated were in the 40's.
I just brought the tanks inside and left in a guest bathroom for curing.
Tom
 
Stockmanreef said:
Is it worth purchasing a Semco gun for applying the sealant? Or should I just stick with the syringe method.
Click to expand...

I spread the stuff with popsicle sticks. Worked well.

If you were gonna build 5 airplanes or something, a semco gun might make sense. A better application method just isn't gonna save you much time or improve the quality of your work.
 
I was sort of thinking the same thing. I just caulks a shower with a caulk gun and regardless of the number of times I caulk something, I always end up with a mess. I assume that this will be the same with sealing tanks. Unlike a shower, the tanks don't need to be pretty, just sealed.

thanks
ken
 
i bought a Semco gun on ebay for around $50 bucks. Bought disposable 2 oz. cartridges and nozzles from Aircraft Tool Supply.

It made the job so much easier than on my first build.
Highly recommended.
Tom
 
You can nuke the resin (not the hardener) for a few seconds in the microwave to get it warm, before mixing. Works great.
 
cold proseal

Ken
I am also working tank parts. I keep the proseal in the house the night before (68 degrees).
The parts change temp so fast there isn't much reason to keep them inside but I do bring the garage up to 55-60 before working with it. After working, I brought the parts back in along with a sample. Two days inside the sample was pretty stiff. I wouldn't call it fully cured but it seems safe to handle.
 
proseal

Read the label. It needs to be above 50 f. I worked at a low bidder FBO on northwest dc9s that had numerous pressurized skin repairs that were done at below 50. When the airplane left and pressurized it blew out all the sealant and had lots of leaks. The FAA paid a visit soon after.
 
I tried the veterinary syringes drilled out to a #30 hole.
Compared to the semco, it required hand squeeze pressure that made it difficult to run a consistent bead in tight spaces. Plus, it tended to drip even after I stopped pushing.

I really don't have a dog in this fight, but I put the ease of using the Semco right up there with a titanium bucking bar. Of course, if I was cionvinced that I won't build a third plane, I could resell it here for what I paid for it.

Tom
 
Hey guys, not even close to building yet, but was wondering WTF is a semco gun, searched Ebay and found this, apparently a bunch for sale, for 20 bucks in case anyone wanted, and if its the same thing.

http://www.ebay.com/itm/Semco-pneum...615?pt=LH_DefaultDomain_0&hash=item19e278d727

anyway keep up the tips guys and gals.

my bad, noticed it does not have the barrel, there are other auctions still up thou for 50-75 bucks that look complete. if you wanted, take a look worse case your out 5 mins.
 
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The sealer is good at lower temps and it will actually give you a longer working time. At our factory here in Wichita the sealer crib will premix a large batch of B1/2 and immediately put it in a -40 degree freezer where it will last for 30 days. Once you thaw it you still have approx 30 minutes of working time. If you elect to warm your sealer I would only do it for the time you are working with it, the rest of the time I would store both parts in the freezer.
Just my 2 cents.
 
I did the ailerons and flaps first just cause I didn't feel like dealing with proseal in my garage in summer. I'd probably do them first and wait till spring.

I like the semco gun. Got it from brown tools and can probably sell it here when done. It's easier to apply (I also tried the syringes) because you don't have to put any effort into pushing the stuff out while you're concentrating on a good bead.
 
Semco alternative

tomhanaway said:
I tried the veterinary syringes drilled out to a #30 hole.
Compared to the semco, it required hand squeeze pressure that made it difficult to run a consistent bead in tight spaces. Plus, it tended to drip even after I stopped pushing.

I really don't have a dog in this fight, but I put the ease of using the Semco right up there with a titanium bucking bar. Of course, if I was cionvinced that I won't build a third plane, I could resell it here for what I paid for it.

Tom
Click to expand...

Here's my take on the syringe v. Semco question. I bought veterinary syringes, drilled the hole out larger, "hot-glued" a short piece of plastic tube in as a nozzle and then put the whole thing in my generic caulking gun. I did this because i found the syringe itself too hard to squeeze by hand. Of course in retrospect, that's probably because my proseal was cold. I'm in New England and heat the garage while working but I never thought to take the proseal inside to warm up-- probably would have been better, but using the caulking gun worked just fine too.
Tanksealing_zps31057122.jpg
 
Stockmanreef said:
Is it worth purchasing a Semco gun for applying the sealant? Or should I just stick with the syringe method.
Click to expand...

The vet syringe and Popsicle sticks work but the Semco gun is much easier. Here's a small write-up I did on my blog: http://larrys-airplane.blogspot.com/2010/07/semco-sealant-gun.html.

If you're shopping ebay, make sure you get the air line that's made for the gun. The fittings looked hard to source. The plastic tubes, nozzles and plungers can be bought at Brown Tools. I have both the 2.5" and 6" and use both. The smaller one is really good for making those fillets inside the tanks. I liked mine so much that I bought several and gave them as gifts.

IMG_0438.JPG
 
Those semco guns are expensive...
I made my own using a regular caulk gun.

I bought the caulk gun with the two rails running between the handle and the end. get them at the Home Depot Aviation Department.

All I did was take my scotch bite wheel and reduce the diameter of the plunger till it would fit in the end of the proseal tube.

Works like a champ... just remember to release the pressure on the trigger when you get done or it will ooze out everywhere.
Jack
 
thanks for the ideas. I am going to attempt the syringe method, maybe modified to use with a caulk gun. I will try this method with the tank stiffeners. If that proves to be a PITA, then I will buy a Semco gun. I have a feeling the I will be buying one. As pointed out selling it should be easy.

Ivan-- I like the PPE (personal protective equipment).

How many people use a respirator while applying sealant?

I wear one while working with anything evolving VOCs. In particular, while cleaning parts with acetone, MEK, or painting.
 
Those semco guns are expensive...
Click to expand...

I just looked at the big auction site and saw 9 listed with most looking complete. Buy it Now prices ranged from about $25 to $99 with some having free shipping. No relation but I've bought from one of the sellers, Faber Surplus, with good experiences. They have the one I like which is the 2.5" with a paddle trigger. I also don't have any stock in Semco but everyone I know that uses them, loves them. For me, my Semco gun is to proseal as a tungsten bucking bar is to riveting.
 
I?m working on my tanks right now. Garage temps in the 30-45 range dependent on outside temps. The pro seal work time was greatly increased, however so is the cure time. After fay sealing the interior ribs on the first tank, it took a good 5 days for it to tack up. After I finished closing the tank up I let it set in the garage for a week and the pro seal was still very pliable. Move the tank inside and it cured in like 3 days. Bubble pressure test indicated zero leaks.:D
 
Stockmanreef said:
thanks for the ideas. I am going to attempt the syringe method, maybe modified to use with a caulk gun. I will try this method with the tank stiffeners. If that proves to be a PITA, then I will buy a Semco gun. I have a feeling the I will be buying one. As pointed out selling it should be easy.

Ivan-- I like the PPE (personal protective equipment).

How many people use a respirator while applying sealant?

I wear one while working with anything evolving VOCs. In particular, while cleaning parts with acetone, MEK, or painting.
Click to expand...

Ken-

I'm pretty careful about PPE these days. Once when I was younger I painted a car using isocyanate based paint with only a particulate filter mask and it earned me a nice vacation in the hospital. They say a person's sensitivity to that sort of stuff only gets worse. I may be being overcautious, but proseal stinks and that's enough to make me be careful. Also, anytime you have proseal mixed you also have MEK fumes from cleaning tools, so the VOC mask is just good, cheap insurance in my view.

By the way, we just air tested that tank this past weekend and found no leaks after soaping, and it's held 27 inches of water since saturday so I'm pretty happy with my results!
 
Semco (or clone) +1

I definitely like the semco gun, used with the vans pre-proportioned semkits of proseal goop. There was much less mess, less air bubbles, and the beads went down nicely. I keep my proseal cartridges in the fridge until ready for use, then let them sit and warm up prior to mixing. Usually there is a little heat when the two parts get mixed, so this helps bring it to work temp. Keeping it a little colder will increase work time, but I only did this for things like the trailing edges. For the tanks, there was plenty of work time, since the gun lays it down so quickly and easily. Can't recommend the gun enough.
 
I actually decided to buy one instead of making a mess. The decision came caulking the shower. I can never get an even bead with a caulk gun. I assume a syringe will be worse. I figure I can always sell it when I am done.
 
Semco gun

I had picked up a used pneumatic gun thinking it would be a luxury. I found that the ability to dispense and control pro seal evenly and consistently, using one hand and feathering the pneumatic trigger on the gun, was an invaluable aid when in the middle of pro seal operations. You can also reuse the plastic cartridges, as pro seal doesn't stick to polypropylene. Simply mix your own pro seal, spoon into the cartridge and dispense. When the slug dries inside the cartridge, unscrew the cartridge nozzle and remove the cartridge plunger with a needle nose, rinse and repeat.
 
Semco Gun

I just did my first batch with the Semco gun. It was really nice to use even though I accidentally put on a 1/16" tip instead of the 1/8" tip. I did not make any mess (other than mixing). One thing I did was the double glove trick which is a great idea. The other thing I did was when I peeled the outer glove off, I put it back on inside out, so I could use them twice.

I unscrewed the tip and pushed out the plunger. I put a screw in the tip so that I could pull out the plug later.

ken
 
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