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Mixing epoxy

#1 
Simplest method of mixing epoxy in the amounts we generally use - a
 pad of "Post Its", and a box of toothpicks.

Not so fast there - this may work, but if you had been reading this
thread in its entirety you would have notice that the tile was
recommended as a non- absorptive surface to substitute for aluminum
foil. Epoxy manufacturers recommend that epoxy be mixed on
non-absorptive surfaces in order to prevent either the resin or
hardener from being absorbed by the substrate and possibly causing a
deficient cure of the epoxy. Sure you can mix it on paper, wood,
cardboard etc and it will probably work most of the time, but it is
better and more controlled to mix it as recommended. Glass, tile,
some plastics, some metals, and other non-absorptive or reactive
surfaces. Glass or tile is best IMO.

For more tips on proper use of epoxy adhesives (as per the
manufacturers) see my website.

Steve Green - Rough and Ready Gems www.briolettes.com
Fine gem briolettes and precision ultrasonic drilling.

#2

Hi: In your article EPOXY SETTING TIPS FOR BRIOLETTES
(http://www.briolettes.com/b_epoxy.htm ) you say:

“6) If using a conical cap, good fit with minimal clearances between
the pieces to be adhered will give your best results. Epoxies are
capable of filling gaps up to 0.040” but a lesser gap will give
better results."

Isn’t 0,040 too thick? (0,040 = 1.016mm)

Best regards.
G. Moura

#3

And for one moRe: Have zillions of little zip lock bags that little
parts and stones come in that have been piling up? I do. They
work great for mixing epoxy with a toothpick. Richard Hart

#4

Wax paper is also a great surface to mix on. Any warnings about
using this as a surface?

Thank you, Reba

#5 
   Wax paper is also a great surface to mix on.  Any warnings
about using this as a surface?

Reba, it sort of depends. Depends on whether or not you’re serious
about getting the ultimate strength from the epoxy. Most people
aren’t very accurate in measuring out the two components, and don’t
mix them really thouroughly either. But then again, in most cases,
it doesn’t matter all that much when there’s plenty of surface area
and little stress. But if you mix epoxy on waxed paper then you’ll
end up with wax in the epoxy. How much difference does that make
… who knows, how much wax, which epoxy system. If it’s a
non-critical application I’m not going to say it won’t work, but I
personnaly wouldn’t do it.

For what it’s worth, having mixed epoxies in specialised industrial
applications, I use a piece of Teflon sheet as a mixing surface.
Now, that’s expensive, and not too easy to get hold of, so an
alternative might be a piece of thick polythene, say cut from an old
bucket.

For mixing I use TWO palette knives. These have straight blades
about 3/4 inch wide, not the small cranked ones. The ends have been
cut off (too flexible) back to stiffer material, and the sharp
corners taken off the cut ends. You use one to do all the mixing
with, then every so often gather all the epoxy back into a small
area, and use the second knife to scape material off the first.
Then go in and mix some more. If you don’t do this you end up wih a
wide puddle that’s well mixed in the centre but which has
indeterminate pockets of one component or the other around the
edges. I learnt this mixing method from the printing ink trade, and
it’s the only way to go, for hand-mixing smallish amounts, if you’re
serious. Oh, and as a rule the slower stuff is stronger than the
fast stuff, especially if you leave it somewhere warm to cure.

As other people have mentioned, leave the excess epoxy on the mixing
pad so that you can geve it a prod to see how it’s getting on. When
cured it pops off the Teflon easily. –

Kevin  (NW England, UK)
#6

I take a strip of aluminum foil, and wrap it around an empty plastic
cassette tape box. It is centered on the non-opening side; then the
ends tuck into the opening. Close the box and the foil is taut. Now
you have a mini portable palette. I mix with an old metal artists’
palette knife, small diamond shape blade, about 25mm. I use this one
only for epoxy. I mix very thoroughly, folding the resin and
hardener back and forth into each other, scraping up from the
bottom, inwards from the sides, etc. The palette knife, designed for
blending of colors, is absolutely perfect for this. As soon as the
epoxy is mixed, I clean the palette knife with alcohol. Alcohol is
not the perfect solvent, but it works as long as the epoxy has not
set up too much, and I always have it around. Spills and oozes clean
up with alcohol too.

I apply the epoxy with a toothpick, and leave it in the glue so I
know when the batch is set. Tear off the foil and use the cassette
box with a new piece of foil next time. I only use slow-setting
epoxies such as 330 and 220. I don’t trust the strength of the
five-minute variety. I will set up the glued work with a swing-arm
lamp pulled close, to accelerate the setting with mild heat if
necessary.

In years past I epoxied almost every day. The aluminum foil and
palette knife have worked very well.

Good luck.
Lin Lahlum

#7

for mixing epoxy i just stick a 3 to 4 inch strip of 2" clear
packing tape onto the bench plate attached to the edge of the work
surface, next to my elbow, fold under a half of an inch to grab for
easy removal, and mix on the smooth top side. if you don’t have a
tape gun, about every office, drug, or discount store has one of the
rolls that comes with a disposable plastic roller with a built in
serrated cutting edge - one roll is about $3.00 and lasts for quite
awhile. another help is to use embroidery needles with large eyes,
upside down, to apply the epoxy - the hole end goes in the mix &
carries enough glue each time, doesn’t drip. to remove old residue
from any surface, break off 1 1/2" of the blunt end of a small wood
skewer, stick it in your flexshaft and the splintery wood does a
great job cleaning without scratching anything. and, as usual, i am
reminding everyone that the best nontoxic, won’t harm skin, pearls,
opals, turquoise, etc., debonder that will remove ‘EVERYTHING known
to stick anything to anything else’ stuff is uncommon
conglomerates.com’s fantastic - are you ready … ‘debonder’. (what?
you don’t have embroidery needles, wood skewers, packing tape? and
you call yourself a jewler?? you probably don’t have chopsticks
either! tsk. tsk!)

good luck -
ive

#8

A brief distinction between 330 and 220: 330 is about 15 min. set
time; 220 much longer. I would avoid 5 minutes epoxies. I have
used 220 for at least two decades without problems using old
business cards and a toothpick.

#9

A brief distinction between 330 and 220: Isn’t it more about the
color after drying? 330 dries water clear, 220 dries yellow.

#10 
A brief distinction between 330 and 220:  Isn't it more about the
color after drying?  330 dries water clear, 220 dries yellow.

220 is also slower setting, and more waterproof, and perhaps
slightly stronger as well.

Peter

#11 
    A brief distinction between 330 and 220:  Isn't it more about
the color after drying?  330 dries water clear, 220 dries yellow. 

220, although amber in color, does not dry yellow.
#12

You have been lucky. I am a volunteer teacher at Temple’s Tyler
School of Art. Inevitably when a student comes to me with the
complaint that their 5 minute epoxy won’t set up and I ask them how
they mixed up, the reply is that they mixed it on a piece of plastic
( usually acrylic or plastic coated paper). My dentist also advised
me that he can’t mix except on glass or metal (paper would not be
handy for him. The explanation is usually that mixing the epoxy
extracts some of the ingredients from the plastic mixing surface. I
make it a rule to always mix on scrap metal, paper, wood or
equivalent. Frank Johnston.

#13

Denice

I use a lot of 5 min and the 30 min Devcon product. And I don’t the
think the plastic baggie can affect the 5 min epoxy. It’s a great
mixing technique you use!! And you don’t have to smell the epoxy as
you mix it. I’m going try it with the 30 min epoxy. I,ll let you
know if there’s a problem, but I don’t expect it NOTE: You can buy
these product wholesale from B. E. ATLAS in Chicago at 800 305
4393… in the 9oz sets, 6 sets to a box, at about 1/2 the retail
price…

Sydney Cash
@Sydney_Cash

#14

Some of the electrical casting kits for waterproofing underground
cables actually are sold in a plastic bag system. They have a thick
outer bag with a thin divider inside. You poke a hole through the
inner bag and keep squashing it around to mix it. Then cut a corner
off and pour while cursing the mess on your pliers :slight_smile:

Unless they use a special bag plastic, I can’t see anything really
different to what you are doing. The one difference with casting
kits is that with big quantities of epoxies in them, they can get
uncomfortably warm when mixing!

At least it is clean and stops chemical contact.

Reagards,
Brian.
Sunny Mackay, Nth Queensland, Australia.