The Murphy Builders Site

Jason, before you go taking all the proseal off, give it a week or so and
see how it sets up. It is TOTALLY normal to be able to take your thumb nail
and carve proseal clean off the aluminum after it has just gone tack free,
and even for some days after you have done the work. I have had times in low
humidity/temp times of the year that I've had to blow heat over a pan of
water on it's way into the tank area to get the stuff to cure up and stop
being able to easily peel. Proseal like sikaflex is hydroscopically cured.
Ie it needs humidity to help the cure, but I'm sure there is lots over in
Scotland!

If it doesn't harden up a bit more for you shortly and if you mixed your
proseal from that seemingly empty catalyst container, maybe it was missing
something important.

Also, SORRY BOB, I have never followed that recommended clean first, scuff
second, blow off and then proseal (you are going to be putting proseal on
top of a LOT of dirt!). I always drill and debur the tank area, then give a
quick wipe with Acetone to get the old storage/processing dirt/grease and
plastic wrap scum. Then I scotchbrite a good cross hatch pattern into every
joint seam for the Proseal to bite into, then I wipe clean again with lots
of Acetone (changing towel continuously) on the entire piece and set the
stuff aside for the acetone to evaporate totally. If the stuff is going to
sit around for a few days I cover everything up with poster board to keep
dust off, BUT mostly to save them from the curious "dropper bys" that seem
to have a need to put their fingers everywhere. I have had only one fuel
tank that ever leaked and that was my own very first Rebel that had a pin
hole down the upper stringer closest to the main spar because the proseal
slumped away (now I flip the wings over right after installing the top tank
skin so it "auto fillets"). I have built over a dozen leak free wings, so I
must be doing something right! I rarely use 3/4 of a quart of proseal per
tank. Even on the SR with 4 bay tanks I only used 3 pints (1 QT and a 1/2)
of Proseal and this includes the proseal required between the spar doublers
and solid rivets! More proseal doesn't stop leaks, it just makes it harder
to fix if they do leak because it all has to be removed to bare metal to
form a new membrane over the seepage area.

Keep in mind that when you touch bare aluminum with your thumb, the oil from
the body contaminates for a radius of about 3 to 4 inches! That is why I
cover everything up once cleaned, because the shop "drop bys" seem to be
attracted to bare, freshly scotchbrited aluminum the flies to $^it and when
you are not watching they will put their grubby fingers all over your
prepped areas!

Best Regards,
Wayne G. O'Shea
www.irishfield.on.ca

----- Original Message -----
From: "Rick Harper" <rjwh@ozemail.com.au>
To: <murphy-rebel@dcsol.com>
Sent: Friday, November 09, 2001 5:28 PM
Subject: Re: Don't pick you nose, or proseal...

G'day from OZ Jason !

I read time and time again of guys having problems with fuel leaks
etc.....so I was rather cautious when it came time to Pro-Seal the wing
tanks (to say the least).

I extended our tanks by one rib...and we have 240 litres(English spelling)
capacity....
and ABSOLUTELY NO LEAKS !!!

I'm certain that if you can "peel off the set Pro-Seal" ..you have a

problem

!
Take off what you have done so far and start again ! (sorry)

1) You HAVE to clean the surfaces with volatile spirits !!!!!!!! (I used

a

scotch bright pad, thinners and then MEK (make sure you don't breath the
stuff too much either !)

2) Put LOTS of Pro-Seal on.... on ALL sides...front , back, bottom &
top,....don't hold back ....who's gonna see it anyway !?!?!?!
(I used the two 1 litre kits just to do the two bottoms and sides of the
fuel tanks...and ordered another 1 litre kit just to do the two

lids....and

NO LEAKS !

Rick & Wendy Harper
541R Flying :-)
----- Original Message -----
From: Jason Beall <super_rebel131@yahoo.com>
To: <murphy-rebel@dcsol.com>
Sent: Friday, 9 November 2001 18:14
Subject: Don't pick you nose, or proseal...

Hi all,

I've had my first 'Proseal experience'. This stuff is
sticky!

Another Proseal Question...

I cleaned my aluminum really well, wiped it down with
a clean, dry cloth and went at it. No MEK or Acetone.

Mixed it as per instructions on the can. It set up
alright. It's resiliant, but if you pick at it it will
peel up. Is this normal? I practiced on a coulpe
pieces of scrap I riveted together. I think i'm ok,
but i was amazed at how relatively easy it it to
remove.

Any suggestions? Any others have any Proseal
'learnings' to pass on. All in all, it's not the
nightmare people make it out to be.

-Jason

=====
________________________________________________

Jason Beall
Super Rebel No. 131
Aberdeen, Scotland, UK
super_rebel131@yahoo.com

__________________________________________________
Do You Yahoo!?
Find a job, post your resume.
http://careers.yahoo.com

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Dave,
To add to the suggestions, research the archives for some numbers for SealPak proseal product for thicker and brushable grades. Also be sure to allow for temperature related cure time variations. It halves for each 10 degrees above 70. We found the small, metal shank, stiff bristle brushes 1/2 inch wide often called "acid brushes" by the welders are useful. The popsicle sticks are available at WalMart here as "craft sticks". They are necessary for mixing and troweling. As stated elsewhere do put a layer on each surface. In my opinion this is not a time to be stingy with material. No one ever had a tank leak because they put too much ProSeal on the joints. I would also dip each rivet as installed. Due to cure time this is really a time to gather extra help to dip and push rivets. Also to do an external solvent clean up before the ProSeal hardens.

One critical consideration is to be sure there is a clear path for fuel and water to run to the wing sump drain. The stringer must be cut back far enough and no ProSeal dam formed at the root end. We will have to cut one wing open to remedy this safety issue.

We aligned our ribs to the wing by using a number of 1/8" black steel rods down through the rivet holes. With help keeping the rods in place and straight the skin is then slipped over the rods in the matching holes and the skin lowered. This pulls the ribs into alignment for clecos.

Be sure to throughly seal the rear bulkheads, tank corners, and stringer penetrations at the outboard solid tank rib. We didn't and then paid the price. You get a second chance before installing the top skin to go over the inside again. We used brush grade and tried to be thorough but still missed a bulkhead bottom and corner leak. We found these leaks by using a stethoscope with a long tube for listening. When the tank has any pressure there is a loud whoosh from the leak.

Good luck and wear old clothes,
Ralph Baker
Elite 624E (reserved)