REFLECTOR: Jeffco question

[Brett Ferrell]

Grigore,

I would definitely thicken it up with some Cabo and flox, especially for
the side walls.  The new hardener doesn't set nearly as fast as the old
stuff (which would pop into a rock-hard flaming ball if you looked at it
wrong).  With that said, the volumes you're talking here seem a little
large to me, particularly if you only have your set of hands.  You need
to keep "pulling" it up the side walls if it ends up too runny (and to
some extent even if it isn't), and at least the old stuff exothermed
much faster in bulk, so I would mix smaller batches and keep it moving
myself.

And get some help if at all possible.  Most anybody can handle a brush.

And plan to ruin whatever shirt you're wearing.  (Apparently this can be
avoided, but don't ask me how - I don't know).

Brett

Grigore Rosu wrote:
> Thanks Ronnie.
>  
> Hm, this is in contrast with what Scott Swing told me last week; I
> guess there are different ways to do it.  It was him who recommended me
> the composition above and he said that I should use a squeege, lay two
> coats of Jeffco, and use the same paste to bond the top strake.  There
> were many things he told me and many things I forgot to ask; in
> particular, I am not sure whether it is best for the top strake to cure
> all together in place as it's being bonded, or to do what you suggested.
> Grigore
> On Feb 8, 2008 4:25 PM, Ron Brown <romott at roadrunner.com
> <mailto:romott at roadrunner.com>> wrote:
> 
>     Grigore,
>      
>     I don't think you need the flox and cabosil for coating the fuel
>     tanks, bulkheads and baffles.
>      
>     Just mix and apply the Jeffco and watch for bubbles to form - prick
>     them with a tooth pick or use a small paint brush.  The key is to
>     stay with the Jeffco until it sets and no more air bubbles appear. 
>     I didn't watch for the bubbles, let it set and had a bunch - so I
>     had to sand it and apply a second coat - which only added more
>     weight.  Not good.
>      
>     Go ahead and paint the underside of the upper strakes too.  Just
>     roughen the Jeffco where the stakes meet the bulk heads and baffles
>     before installing the strakes.
>      
>     Some folks have used the Jeffco to install the strake tops - then
>     you would use flox and cabosil to make more of a putty that will
>     stand up and fill the gaps between the bulkheads/baffles and the
>     upper strake.
>      
>     Ronnie
> 
>         ----- Original Message -----
>         *From:* Grigore Rosu <mailto:grigore.rosu at gmail.com>
>         *To:* Velocity Aircraft Owners and Builders list
>         <mailto:reflector at tvbf.org>
>         *Sent:* Friday, February 08, 2008 4:06 PM
>         *Subject:* REFLECTOR: Jeffco question
> 
>         I understand that Jeffco cures much faster than EZ-84, so it is
>         not a good idea to prepare too much at once when sealing the
>         tanks.  Also, it appears that it is a good idea to mix it with
>         flox and cabosil.  I'm thinking of mixing the following at one
>         time each time:
>          
>         - 2 cups of Jeffco
>         - 1 cup of hardener
>         - 3 cups flox
>         - 3 cups cabosil
>          
>         Also, I'd like to give a first coat, then 8-12  hours later give
>         a second coat, then 8-12 hours later seal.
>          
>         Does this sound right?
>          
>         One thing I'm not sure about is how to deal with the top
>         strake.  Should I coat it at the same time I coat the rest of
>         the tank, or I should just coat it before sealing?  I'm worried
>         that if I coat it following the same timeframe as for the rest
>         of the fuel tank, then I may end up with a layer of sealant on
>         the top strake that is thicker than 1/8'' - 3/16'', which is the
>         gap I currently have between the bulkhead flanges and the top
>         strake.
>          
>         Thank you,
>          
>         Grigore
> 
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