REFLECTOR: Tank sealing and Strake closing

[Chuck Harbert]

Guys, a couple of comments made me wonder if I was understanding this 
correctly. I wrote recently about mixing epoxy and cabo (peanut butter 
consistency) to seal the inside of the tanks. A very thin layer will cover 
pinholes and none will appear afterwards. Although I've not used Jeffco, I 
think Kurt commented about fixing a leak using Jeffco and cabo which would 
be the same. Heck, you could do both to be sure you have no leaks (I had 
none).

The comment about using epoxy and micro (ballon) to join the (top and 
bottom) strakes worried me because I thot you never use balloon it a 
structural situation, only for filets and fills. We joined my strakes with 
epoxy, cabo, and milled fiber which is what I think it calls for.

I was told that anytime you join metal to glass (aluminum tubes into tanks) 
that you use Alphapoxy because it bonds better and won't leak. Don't forget 
to sand the metal too.

Have I got this right?

Chuck H
--------------------

Kurt wrote:
> My knowledge has to be tempered with the fact that I have not flown my V 
> yet.
> I have leak tested the tanks and all is well.
>
> What I did was:
>
> Grooved the foam out a bit on all sides of the baffles and bulkheads. Then
> packed them with Micro and Jeffco. then sanded them a bit (for bite) and 
> glassed
> in per the plans.
>
> Made "cap strips" as many have talked about. Installed those.
>
> coated all of the inside of the tank, baffles, bulkheads and the inside of
> the top strake with Jeffco. Let it dry.
>
>   Note:  as it dries, some pinholes from popped bubbles will start to
> appear. I mixed up a little jeffco... and "dripped" it on those holes 
> while the rest
> was still tacky. I did this with a toothpick. That took care of most of 
> the
> pinholes.
>
> Once it had dried, I sanded all the Jeffco to get some "tooth" to it.. for 
> my
> next coat.
>
> Once I was ready for the "closing"... I recoated the bottoms of the tank, 
> and
> bulkheads with Jeffco.... so whatever falls off of the cap strips sticks 
> into
> the fresh Jeffco.
>
> GET HELP.  You dont have enough hands to do this in a timely manner by 
> your
> self.
>
> Then mix up Jeffco structural (not the sealant) with Micro. apply to the 
> cap
> strips so you have a good sealing mound.
>
> put on the top... weigh it down.. and wait.
>
> Go do the other one.
>
> Like I said before.. I had a couple small leaks. They were hard to find 
> with
> a single balloon on the tank line. So I put a big party balloon inside 
> another
> one. Filled with a compressor.. and affixed to the fuel tube. That gave me
> enough extra pressure to find the leaks with soapy water. In both cases.. 
> they
> were in the forward, outboard, upper strake to bulkhead area (where the 
> radius
> is small).
>
> I mixed up some Jeffco and Cabbo... and hooked a long tube to the fuel 
> line
> (previously used for leak testing).  drew a vacuum with the tube in my 
> mouth
> and "painted" the leaky area with the mix. In essence.. pulling it into 
> the
> leak. Once that was done.. I added a bit of Micro to the mix.. and put a 
> small
> fillet over the area too.
>
> The next leak tests were a success.
>
> Hope that helps.

>
> Question for the knowledgable,
>
> Anyone have the difinative answer on these?
>
> Is it better to seal the tanks with the Jeffco right before you close the
> fuel Strake or is it ok to paint the Strake walls days even weeks before 
> you plan
> on sealing the strake? Can you mix Jeffco with micro glass and use like
> EZ-poxy? Bonding abilities with aluminum?
>
> I haven't used this stuff yet...Sure smells good though, the wife is love
> this stuff, ahh...the joys of building at home. Thanks in advance for your 
> input
> all.
>
> Larry Lambert.
> XL/
------------------------
>
> Larry,
>
> Ok - I'll answer....but since you said question for the
> knowledgeable.....:o)
>
> A: I think it's better to paint in conjunction with closing the strakes.
>
> I like to chemical bond the Jeffco IF you have the chance to do so.  We
> did all of the prep work on our strakes - ALL - and had everything setup
> to be able to just do the Jeffco, and then seal the strakes.  We used
> two coats - and applied them within the chemical bonding period - it's
> been a while - so I don't ember the exact # of hours.
>
> We bonded the strake using Jeffco, glass and flox and cabo - which is
> what was suggested by Scott Swing.  We used Aeropoxy for all other
> bonding - that was not part of the tank sealing area - you will find a
> portion of the leading edge to be in this 'area' - as well as the strake
> to the spar.
>
> Jeffco colorant can separate - so I'd suggest really mixing the product
> - but it is NOT problem - per Engr. Tech support at Jeffco.
>
> Scott Swing has said something like... "build the parts out of ez, bond
> with Aeropoxy."  I don't remember exactly what he said about aluminum -
> but I know he didn't have an issue with it for the strakes - we bonded
> in the vent tubes with Jeffco.  We did not bond in the aluminum for the
> fuel senders or the finger strainers - those we used Aeropoxy - we
> covered them with bid - and then like everything else-  Jeffco.
>
> As always - contact the factory if you have any concerns - and contact
> Jeffco Engr support - good people.
>
> And don't try the above with just 1 or 2 people....we tied up 4 people
> for the better part of 2 days.
>
> BTW - I have a bunch of pictures if you are interested...
>
> John