<br><font size=2 face="sans-serif">Jason</font>
<br>
<br><font size=2 face="sans-serif">When you say finishing resin do mean
epoxy or polyester? I do not understand your configuration of bonding the
horns, but if the bond is the only thing holding the horns on, best use
and adhesive. Laminating epoxies and all polyesters have low peel
strength = bad bond characteristics. Horns will experience a cleave stress
which is shear+peel, if there is any flex then lots of peel stress.</font>
<br>
<br><font size=2 face="sans-serif">A <b>good</b> adhesive has thousands
PSI shear strength, but only 25 lbs of peel. Laminating resins peel = 0.<br>
</font>
<br><font size=2 face="sans-serif"><br>
Gray Fowler<br>
Senior Principal Chemical Engineer<br>
Radomes and Specialty Apertures<br>
Technical Staff Composites Engineering<br>
Raytheon</font>
<br>
<br>
<br>
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<td width=40%><font size=1 face="sans-serif"><b>"J Shu" <jshulman@cfl.rr.com></b>
</font>
<br><font size=1 face="sans-serif">Sent by: nsrca-discussion-bounces@lists.nsrca.org</font>
<p><font size=1 face="sans-serif">03/16/2009 11:46 AM</font>
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<div align=center><font size=1 face="sans-serif">Please respond to<br>
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<td><font size=1 face="sans-serif">"General pattern discussion"
<nsrca-discussion@lists.nsrca.org></font>
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<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td><font size=1 face="sans-serif">Re: [NSRCA-discussion] thinning epoxy,
how?</font></table>
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<br><font size=3 color=#000080 face="Arial">So much good info. I'm gonna
use Finishing resin to seal the motor area. </font>
<br><font size=3> </font>
<br><font size=3 color=#000080 face="Arial">How bad of an idea would it
to be the finishing resin to glue in the fiberglass horns into the wood
surfaces?</font>
<br><font size=2 face="Arial"><br>
Regards,<br>
Jason</font><font size=2 color=blue face="Arial"><u><br>
</u></font><a href=http://www.shulmanaviation.com/><font size=2 color=blue face="Arial"><u>www.shulmanaviation.com</u></font></a><font size=2 color=blue face="Arial"><u><br>
</u></font><a href="http://www.composite-arf.com/"><font size=2 color=blue face="Arial"><u>www.composite-arf.com</u></font></a>
<br><font size=3>----- Original Message ----- </font>
<br><font size=3><b>From:</b> </font><a href=mailto:gfowler@raytheon.com><font size=3 color=blue><u>Gray
E Fowler</u></font></a><font size=3> </font>
<br><font size=3><b>To:</b> </font><a href="mailto:nsrca-discussion@lists.nsrca.org"><font size=3 color=blue><u>General
pattern discussion</u></font></a><font size=3> </font>
<br><font size=3><b>Sent:</b> Monday, March 16, 2009 11:44 AM</font>
<br><font size=3><b>Subject:</b> Re: [NSRCA-discussion] thinning epoxy,
how?</font>
<br>
<br><font size=2 face="sans-serif"><br>
Jim</font><font size=3> <br>
</font><font size=2 face="sans-serif"><br>
Polyesters will not cure when in contact with oxygen, leaving a sticky
surface. If your surface is not sticky after applying-curing polyester
then you are using a "true" polyester finishing resin, which
is fine, BUT look out because to stop the oxygen inhibition polyester "finishing"
resins add 5% wax, which floats to the surface and blocks the oxygen. I
say lookout, because any future bonding to this area will be extremely
poor. If you are not bonding to an area saturated with this resin you are
fine.</font><font size=3> <br>
</font><font size=2 face="sans-serif"><br>
K&B paint was fine, just a regular epoxy cured with a polyamide, meaning
the mixture needs to be "inducted" prior to use, that is mixed
up and then sits in a mass for a t least 15 minutes (read the instructions)
or the polyimide will slightly separate giving you a sticky surface.</font><font size=3>
<br>
</font><font size=2 face="sans-serif"><br>
Unfamiliar Formula U, but Concept clear works very well.</font><font size=3>
<br>
</font><font size=2 face="sans-serif"><br>
I always clear coat with Concept 2021..easy, lightweight and more durable.
My entire engine area is sealed with Concept clear or laminating epoxy.</font><font size=3><br>
</font><font size=2 face="sans-serif"><br>
<br>
<br>
<br>
Gray Fowler<br>
Senior Principal Chemical Engineer<br>
Radomes and Specialty Apertures<br>
Technical Staff Composites Engineering<br>
Raytheon</font><font size=3> <br>
<br>
</font>
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<td width=46%><font size=1 face="sans-serif"><b>"J N Hiller"
<jnhiller@earthlink.net></b> <br>
Sent by: nsrca-discussion-bounces@lists.nsrca.org</font><font size=3> </font>
<p><font size=1 face="sans-serif">03/16/2009 10:16 AM</font><font size=3>
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<nsrca-discussion@lists.nsrca.org></font><font size=3> </font>
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<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td><font size=1 face="sans-serif">Re: [NSRCA-discussion] thinning epoxy,
how?</font></table>
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<br>
</font><font size=2 color=#000080 face="Arial"><br>
Thank you for the very informative information. I have never used epoxy
for fuel proofing. I've used Polyester finishing resin and K&B epoxy
paint until I ran out and recently Formula-U Polyurethane paint. What are
your thoughts on these alternate materials?</font><font size=3> </font>
<p><font size=2 color=#000080 face="Arial">I find fuel proof compromising
gouges are more visible using colored paint rather than a clear coating.</font><font size=3>
</font>
<p><font size=2 color=#000080 face="Arial">Jim Hiller</font><font size=3>
</font>
<p><font size=2 face="Tahoma">-----Original Message-----<b><br>
From:</b> nsrca-discussion-bounces@lists.nsrca.org [mailto:nsrca-discussion-bounces@lists.nsrca.org]<b>On
Behalf Of </b>Gray E Fowler<b><br>
Sent:</b> Monday, March 16, 2009 6:24 AM<b><br>
To:</b> General pattern discussion<b><br>
Subject:</b> Re: [NSRCA-discussion] thinning epoxy, how?</font><font size=3>
</font>
<p><font size=2 face="sans-serif"><br>
Fast curing epoxy adhesives such as the 30 minute are a bad initial choice.
I realize that thousands have used it in these applications, but that still
does not make it a good choice. The non reactive components in the fast
epoxy plasticize with age and methanol and nitro will seriously degrade
the stuff. Using one of the thinner slower curing laminating resins will
require less solvent, if any and provide a much longer lasting barrier.
Any solvent added to an epoxy needs to evaporate completely or you will
created a problem. Denatured alcohol (ethanol) evaporates very slowly.
Cutting a fast cure epoxy with a slow evaporating solvent is a recipe for
trapping alot of solvent, making the chemical resistant even worse. Methanol
evaporates much faster and epoxy is much more soluable in methanol. Be
very careful using ketone solvents (acetone, MEK) or aromatics (Toluene,
Xylene) because many kit manufacturers use styrofoam as a core material
that will be destroyed in seconds with all solvents except the alcohols.</font><font size=3 face="Times New Roman">
</font><font size=2 face="sans-serif"><br>
<br>
SO!</font><font size=3 face="Times New Roman"> </font><font size=2 face="sans-serif"><br>
<br>
1. Use a thin slower cure laminating resin</font><font size=3 face="Times New Roman">
</font><font size=2 face="sans-serif"><br>
2. Use Acetone, MEK or Laquer thinner</font><font size=3 face="Times New Roman">
</font><font size=2 face="sans-serif"><br>
3. NO puddles, super thin coat</font><font size=3 face="Times New Roman">
</font><font size=2 face="sans-serif"><br>
4. Alcohols if you have a styrofoam core</font><font size=3 face="Times New Roman">
</font><font size=2 face="sans-serif"><br>
5. rule #3 again</font><font size=3 face="Times New Roman"> </font><font size=2 face="sans-serif"><br>
<br>
6. If you only need the plane to last 1 year, then use 15 minute epoxy
and do not worry..it will last 1 year or so.</font><font size=3 face="Times New Roman">
</font><font size=2 face="sans-serif"><br>
<br>
Gray Fowler<br>
Senior Principal Chemical Engineer<br>
Radomes and Specialty Apertures<br>
Technical Staff Composites Engineering<br>
Raytheon</font><font size=3 face="Times New Roman"> </font>
<p>
<table width=100%>
<tr valign=top>
<td width=53%><font size=1 face="sans-serif"><b>"J Shu" <jshulman@cfl.rr.com></b>
<br>
Sent by: nsrca-discussion-bounces@lists.nsrca.org</font><font size=3 face="Times New Roman">
</font>
<p><font size=1 face="sans-serif">03/15/2009 02:15 AM</font><font size=3 face="Times New Roman">
</font>
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<td><font size=1 face="sans-serif">[NSRCA-discussion] thinning epoxy, how?</font></table>
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</font><font size=2 face="Courier New"><br>
<br>
I want to add another layer of sealer to the firewall and tunnel on my
plane... what's the best way to do it with epoxy? I've got 30 <br>
minute but not sure how to thin it to seal it.<br>
<br>
Regards,<br>
Jason<br>
www.shulmanaviation.com<br>
www.composite-arf.com<br>
[attachment "IMG_4498 (500 x 299).jpg" deleted by Gray E Fowler/US/Raytheon]
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