Mailing List lml@lancaironline.net Message #25983
From: Dan Schaefer <dfs155@adelphia.net>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: Re: Bond prepping, acetone, paint color, stub wing skin peel.
Date: Mon, 04 Oct 2004 22:12:03 -0400
To: <lml@lancaironline.net>
Scott Krueger wrote:

<<Whilst the appropriate parts (fuelish areas) were bonded with a 3-M
industrial cement (number ?, ............>>.

Scott, if you built around the time I did (started in '86, flew in '93), the
3-M structural adhesive du jour was #3316. At that time, 3316 was the
adhesive of choice by Lancair for bonding together the fuselage halves,
belly pan, wing skins to spars and ribs and the fuel bay close-outs (bottom
wing skins). As far as I'm concerned, it's a super adhesive - coupon tests
confirm that - and even today, on my 235, has not become glass-hard (and
brittle?) like some epoxies we used for wet lay-ups (at that time the plans
called for Saf-T-poxy). On my 235, I can still find a spot where I can
access a 3316 bond squeeze-out and can still make a slight dent in it with a
fingernail if I push long and hard enough. In this case, I believe tough is
better than hard.

N235SP is also a pre-capstrip construction airplane though it seems like
such an obvious thing to do I'm sorry I didn't think of it at the time.

As for bond preparation, builders of that era were advised to use only a
commercial pre-paint cleaner-degreaser called Klix 88. Apparently, Klix 88
is (was? - don't know if it's still available) a powerful oil and wax type
of solvent but not very quick to evaporate giving one plenty of time to blot
it up before it re-deposited the gunk it had dissolved all over the area you
were trying to clean. In my opinion, acetone is less desireable from this
angle because it evaporates so quickly. Yes, acetone will dissolve the bad
stuff quite readily, but when it evaporates it will leave whatever it has
dissolved behind - spread evenly over the area you're trying to clean.

Back in those days, I often flew up to where the Rutan works were located to
listen to their "seminars" (Burt gave some rather informal talks and
demonstrations on working with wet epoxy lay-ups back then) and learned that
the best paper towels for prep was the cheapest, plain white, un-printed,
non brand-name ones as they were far less likely to have any unwanted gunk
in them.

Cheers,

Dan Schaefer


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