Preserving Epoxy (Epoxicles ???)

I am seeking advice about mixing and storing epoxy.

I started my first wooden rib last night after weeks of thinking,
planning, building jigs, cutting gussets, testing, rebuilding jigs.....

I decided to use epoxy for a number of reasons. The problem is mixing
small enough quantities reliably. I decided to make enough to do a
good job rather than economise. I made my first mix and spent a
relaxing hour gluing my first two ribs (in 2 jigs).

At the end of the session I had about 60% of the goop left in a glass
jar. The pot life is 2.5 hours and I had the glue open for only 30
minutes. What the heck ... I put the lid on and placed it in the
freezer.

This morning, the lid came off ... so freezing does stop it from curing
.... but is it any good?
The epoxy 'fresh' from the freezer is really thick... way too thick for
a brush. This is a good thing .. it does not run in the Texas heat!!!!
The viscosity is perfect for smeraring small quantities onto rib stock
with a tooth-pick ... it stays put and does not run before I fit the
stick.
By the time I had glued the rib sticks and way ready for the gussets,
the epoxy had softened and was now perfect (not too runny) for a small
brush to prepare the glue lines for the gussets (todays and the 'other
side' for yesterdays).

With 30% left, back to the freezer.

My discovery that frozen epoxy is more controllable than room temperate
makes life easier.
Freezing means that I can make reliable sized batches and not have t
throw the remainder away.

This seems too good to be true!!! Where is the catch? Will freezing
harm the ultimate strength or any other 'significant property' of the
epoxy. I'd really hate to be doing something unsafe.
Has anybody else done this?
I will test my first ribs to destruction, just to make sure.

Thanks
Steve

while you are making ribs with the frozen glue take a couple of scrap rib
sticks and make a few test coupons. when they are set test to destruction.
if the wood fails, good glue. if the glue fails, time to re-think the
system.

R. Burns

"steveukman" wrote in message
oups.com...
I am seeking advice about mixing and storing epoxy.

I started my first wooden rib last night after weeks of thinking,
planning, building jigs, cutting gussets, testing, rebuilding jigs.....

I decided to use epoxy for a number of reasons. The problem is mixing
small enough quantities reliably. I decided to make enough to do a
good job rather than economise. I made my first mix and spent a
relaxing hour gluing my first two ribs (in 2 jigs).

At the end of the session I had about 60% of the goop left in a glass
jar. The pot life is 2.5 hours and I had the glue open for only 30
minutes. What the heck ... I put the lid on and placed it in the
freezer.

This morning, the lid came off ... so freezing does stop it from curing
... but is it any good?
The epoxy 'fresh' from the freezer is really thick... way too thick for
a brush. This is a good thing .. it does not run in the Texas heat!!!!
The viscosity is perfect for smeraring small quantities onto rib stock
with a tooth-pick ... it stays put and does not run before I fit the
stick.
By the time I had glued the rib sticks and way ready for the gussets,
the epoxy had softened and was now perfect (not too runny) for a small
brush to prepare the glue lines for the gussets (todays and the 'other
side' for yesterdays).

With 30% left, back to the freezer.

My discovery that frozen epoxy is more controllable than room temperate
makes life easier.
Freezing means that I can make reliable sized batches and not have t
throw the remainder away.

This seems too good to be true!!! Where is the catch? Will freezing
harm the ultimate strength or any other 'significant property' of the
epoxy. I'd really hate to be doing something unsafe.
Has anybody else done this?
I will test my first ribs to destruction, just to make sure.

Thanks
Steve

In article .com,
"steveukman" wrote:

I am seeking advice about mixing and storing epoxy.

This also works on epoxy primers, and, to a limited extent, 2-part
polyurethane paints. I would imagine that it also works on fuel tank
sealants.

Freezing slows down the chemical reaction and greatly extends pot life.

Orval Fairbairn wrote:
In article .com,
"steveukman" wrote:


I am seeking advice about mixing and storing epoxy.


This also works on epoxy primers, and, to a limited extent, 2-part
polyurethane paints. I would imagine that it also works on fuel tank
sealants.

Freezing slows down the chemical reaction and greatly extends pot life.

Its been a while since I took organic chem, but I seem to remember a
rule of thumb that said organic reactions slow down by half every 2
degrees C lower you take them.

"steveukman" wrote in message
oups.com...
I am seeking advice about mixing and storing epoxy.

For 15 bucks you can buy an electronic scale on EBay with an accuracy of a
tenth of a gram that will allow you to mix tiny batches of epoxy.
Personally, I wouldn't feel comfortable with using previously frozen, mixed
epoxy for an airplane unless the epoxy manufacturer okayed it, but I'm a
coward. My advice is to get an accurate scale and only mix as much as you
need.

By the way, which epoxy are you using that has a 2.5 hour pot life in the
Texas heat?

Best,
Dennis Johnson
Legacy #257, first flight expected in three months

Thanks for all the ideas. I really appreciate the helpful nature and
experience of this group. I most certainly will be doing materials
testing .... the first few ribs were going to be sacrificially tested
anyway .... finally a use for a teenage son and a Bowflex!!!.

I had tried syringes (from a photographic chemical supplier), but the
epoxy seems way too thick to dispense accurately in really small
quantities by this method or by pouring. I have some 80 year old
chemical balance scales that are good to .01g .... but goop management
seems to be the limiting factor.

The glue that I am using is called "Hexcel" by Aircraft Spruce,
described as similar to T88 and the 'slow cure' version seems to have a
great pot life.

Thanks
Steve

Dennis Johnson wrote:
"steveukman" wrote in message
oups.com...
I am seeking advice about mixing and storing epoxy.

For 15 bucks you can buy an electronic scale on EBay with an accuracy of a
tenth of a gram that will allow you to mix tiny batches of epoxy.
Personally, I wouldn't feel comfortable with using previously frozen, mixed
epoxy for an airplane unless the epoxy manufacturer okayed it, but I'm a
coward. My advice is to get an accurate scale and only mix as much as you
need.

By the way, which epoxy are you using that has a 2.5 hour pot life in the
Texas heat?

Best,
Dennis Johnson
Legacy #257, first flight expected in three months

For 15 bucks you can buy an electronic scale on EBay with an accuracy of a
tenth of a gram that will allow you to mix tiny batches of epoxy.

50mm syringes from the farm supply store, or Woodworkers Supply works
great for small quantities if you can mix by volume. Woodworkers also
has small cups, sticks, and acid brushes for a reasonable price. No
need to resort to the freezer trick..............
================
Leon McAtee

wrote:

For 15 bucks you can buy an electronic scale on EBay with an accuracy of a
tenth of a gram that will allow you to mix tiny batches of epoxy.

50mm syringes from the farm supply store, or Woodworkers Supply works
great for small quantities if you can mix by volume. Woodworkers also
has small cups, sticks, and acid brushes for a reasonable price. No
need to resort to the freezer trick..............
================
Leon McAtee

Forgot to mention the standard trick to make this work is to break off
the tip of the syringe - leaving a larger hole.

In article .com,
" wrote:


For 15 bucks you can buy an electronic scale on EBay with an accuracy of a
tenth of a gram that will allow you to mix tiny batches of epoxy.

50mm syringes from the farm supply store, or Woodworkers Supply works
great for small quantities if you can mix by volume. Woodworkers also
has small cups, sticks, and acid brushes for a reasonable price. No
need to resort to the freezer trick..............
================
Leon McAtee

Another technique is to place the "glue pot" on ice, to extend pot life.

Resort to? Once I discovered it, I thought it the superior way to
preserve epoxy! Particularly when doing fiberglas lay-ups that because
of time constraints took a week to finish.

wrote:

No need to resort to the freezer trick..............
================
Leon McAtee




--
Bruce A. Frank