Subject: Re: Release wax
From: Mike Crawford
Date: 10/22/2018, 12:47 PM
To: harryproa@yahoogroups.com.au


  For both wax and vaseline, all traces of any surface contamination have to be removed before bonding or painting.  This is always true.

  The real test is to create test panels, clean them as you would if it were your boat, cut them into coupons, bond them with a compatible epoxy, and do destructive pull tests the way Practical Sailor did.  And they thought they had fully cleaned the PVA test samples...

  I've seen a scarf bond fail, months later, when a friend didn't fully prep the surface before gluing.  "Hey, did you wipe that scarf down with xylene again before you glued it?"  "Um, no, we didn't have any, so we used some rubbing alcohol".  And that was on non-blushing epoxy, glued with the exact same epoxy, without any release agent used at any phase!

  The destructive test that compares stress-at-failure is a much more scientific and safer way to test than to see what happens later.

        - Mike



'.' eruttan@yahoo.com [harryproa] wrote on 10/22/2018 11:21 AM:
 

| How will epoxy bond to glass fibres with vaseline on them?
| Wax is harder (when dry).than vaseline, so shouldn't stick to the fibres, imo

We had the same concern. We took a piece of glass and put a small amount of Vaseline on it and heated with a gun and spread it out with a brown paper napkin. The heat makes it spread like mad. The reason for the brown is that it changes color to a darker brown when it gets greasy. When the Vaseline was well spread, we then took another clean napkin and wiped the area down while heating. This absorbed any extra Vaseline, leaving a very, very thin film.

When cooled we laid a new unfolded brown napkin on the surface and put a weight on it and dragged it around, we saw no Vaseline on the napkin. Unfolded brown is very thin and changes color.

So we thought we would not need to worry about the fiberglass.

Of course, with II, the fibers never touches the mold anyway.

In my case I have only done this once. And I will be doing it mostly weekly. I'll give updates.

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