Nicholas,

I had the same problems when I did my fuel tanks.  Are you using a
syringe to measure out the two part sealer?  It has been suggested that
the tiny bit of silicon that is on the plunger of the syringe could
contaminate the mixture and cause pinholes.  Try another measuring
method.  Supposedly, you cannot clean off the silicon enough.

A few more suggestions:

1.  Ensure the surface is cleaner than you can get it.
2.  I had good results when I used a squeegee to apply first coat.
3.  Some have had good results when using spray painting equipment.
4.  I seem to remember having better results in warmer temperatures.

You don't want to have any pinholes in the sealer.  The pinhole would
not be sealed.  I have heard of some builders using Jeffco epoxy to
seal the tanks.  I haven't heard of any results of it though.

Try this experiment:

  Take a jar of 100LL and throw in a sample of what is under the sealer
(epoxy layup or prepreg) and see if the fuel attacks it over time. Then
you will have an idea of what might happen if fuel does get past the
sealer.

Actually, you probably could get away with a few pinholes, but would
you want to test the theory?  It it much easier to make it the best you
can now than have to try to fix fuel leaks later.

I remember standing there popping all those little bubbles as they rose
to the top.  Yuck!  The second wing I did, the temperature was quite
warmer and I used a squeegee for the first coat.  A lot fewer pinholes.
 I applied a total of 2 thin coats without allowing cure between coats.
 Only waited a few hours to start second coat.

To fix the pinholes that I missed, I sanded them off down to the
prepreg and reapplied the sealer in little masked off squares.

I wish I had better advice for you.  
Good Luck,
Mike Salzman
Fairfield, CA
LNCE

--- Nicholas Paczkowski <npaczkowski@telus.net> wrote:
> I am starting to seal my fuel tanks with the Jeffco 9700 Fuel tank
> sealer.
> When I brush it on, little air bubbles come up through the sealer,
> then
> burst leaving a tiny to small  pinhole.
>
>  
>
> 1.                Is there an application technique to avoid
> pin-holing?
>
> 2.                Is there an easy way to fix pin-holes?
>
> 3.                How critical is it to find and fill each pin hole?