Storing Epoxy in the Refrigerator

[MrAl]

Hello,

Recently a friend bought some of that "Mighty Putty" at a local
shop and he got three sticks and gave me one of them.
I tried it out and it seems to work like other thick, putty like epoxies
i have tried, but the point of this post in not to critique the product but
how to best store epoxies like this, even the more liquid type.

Since the product description says that the shelf life is only about
6 months and many times i will go for a year without using any
epoxy at all, i would like to try storing this in the refrigerator.
The idea is that the epoxy ages more with higher temperatures
and less with lower temperatures, so it makes sense that the
shelf life of epoxy can be extended by keeping it cool.
I have read that freezing it does not hurt it either, as long as it
is given ample time to thaw before using again, but i dont intend
to freeze it, just keep it at about 40 to 45 degrees F until it is
needed again and then take it out of the fridge and allow time for
it to reach room temperature before use.

Note that i already intend to seal it up in three air tight packages
before storage: one plastic inner wrap, one plastic tube, and one
plastic outer wrap.

Ideas/Suggestions?

Thanks much...

[haklesup]

In theory it should work, just about all chemical reactions are slowed at lower temperatures. While the epoxy reaction shouldn't start until mixed, it can oxidize and photoreact. You will want to wait for it to warm to room temp before using as it will be very stiff and may not cure vary fast or mix properly or have enough surface tack to stick to the workpiece if too firm or cold.

As for air tight storage, many plastics are not hermetic and allow oxygen to leak through, over a year, LDPE and HDPE will only offer minimal protection. Use an oven bag or maybe a used medicine bottle and use one that also inhibits light (though storage in the fridge does a good job of that). A glass test tube and a rubber stopper would be even better.

On a similar note, I find storing any kind of battery except a carbon-zinc in a refrigerator unnecessary and sometimes damaging to the cell. With most batteries, you only need to avoid any extremely hot events.

[Bob Scott]

Other amateur photographers and myself used to buy 35mm film in 50 foot rolls and wind our own cartridges. We kept them refrigerated in the little plastic film containers. Maybe if a few film processing locations still exist, they could give you a few empty containers? They are more airtight than pill containers.

Another word for Mighty Putty is "museum putty". How do you find it to work, Al? Does the epoxy have some kind of inert filler?

Some of the uses shown on TV, like fixing water pipes under hydrostatic pressure by applying putty on the outside, are rediculous.

[MrAl]

Hi again,


Thanks for the ideas/suggestions.

Bob:
I find the MPutty to work roughly like PC11 only it dries faster and
is probably of a cheaper material base. It's like PC Farenheit but
the temperature limit is 250 deg C rather than 500 deg C.
Yes, it is probably made with a power like filler material to make it
more like putty. The stick comes in two parts with inner and outer
parts. Squishing and kneading the two together mixes it and starts
the hardening process just like other epoxies.
As far as the commercials go, and as with other epoxies, surface
preparation is paramount to getting the stuff to work at all. Poor
cleaning or other problems can lead to a bond that does not work
at all, while proper cleaning and making sure the right materials
are being bonded in the first place can make a very good bond.
This is so true of any type of epoxy or even glue.
I can easily see it bonding to brick if it is pushed hard into the
pores of the brick, but if not i can see it easily falling off.
And yes, i agree that if the water pipe is under pressure that
the stuff would blow off or at least keep leaking, but if the water
was shut off first and the surface prepared correctly and the stuff
was wrapped around the whole pipe then i can see it working.
I can easily see it working for a drain pipe, where it is kept dry
for a good 12 hours or so while the stuff hardens.
What i am say here though is not particular to Mighty Putty, as i
can see this working for just about any epoxy putty of at least
some quality. PC Farenheit is some of the best stuff i have ever
tried, but it's about 5 dollars for 1 ounce, while the Mighty Putty
is 3.33 dollars for 2 ounces, so do the math, and use MP when
possible i guess (this is when you can get it locally for the price of
10 dollars for three 2 ounce sticks).

As another side note, i am currently doing a test of MP to see how
well it holds when applied to some plastic that has been roughed
up with sandpaper. I'll see how long it holds. So far so good
(about 2 days now).

[jwax]

I rarely see a use for the putty type epoxies, choosing instead two-component mixes like "JB Weld", or if you're in a hurry- JB Kwik". It's more tolerant of surface conditions since it does flow into a joint somewhat.
Storage is no problem- it'll sit on a shelf for a year or two and still be good to go.
Epoxies have come a long way! Most will give bonds stronger than the native material.
John

[MrAl]

Hi John,

I like the more liquid types too for certain things, especially when the
item or items need better 'wetting' to bond well. At other times however
it is really nice to have a putty like material that you can form into
any shape and it will hold that shape until it gets hard.
For example, i have a pair of ear sound protectors where one side
broke right off. I tacked them together with some more normal
glue, and then after that was dry i mixed up a blob of PC Farenheit and
formed it into a 1/8 inch thick slab, then wrapped that around the arm
that broke and squeezed it all around until it was firmly hugging the
arm over the break. That stuff hardened in the shape that i molded
it in, and now the arm is strong again because it is reinforced with
a 1/8 inch plastic sleeve which fits perfectly on the arm (because it
was molded to that shape). If i wanted the same results with the
more liquid epoxy, i'd have to apply one coat, let it dry, apply another
coat, let it dry, etc., until a layer that was thick enough was built up
around the arm. This is why sometimes i prefer the putty type now.
You can use it in ways that are more difficult to use the liquid stuff
where you would probably need a mold to make a given shape.
With stuff like this you can just form in with your fingers (within about
10 minutes that is) and when it dries you have a very hard substance
which is like hard plastic.
Home Depot sells various brands and types of epoxy putties, but i
dont think they sell the MP.

[Lenp]

A Thought,

We use JB Weld first, to fill voids then use a putty-like epoxy over top to provide the strength. It's the best of both worlds!

Len

[MrAl]

Hi again,

Len:
I like that idea too. I thought i used JB Weld but i actually used
"Pro Weld" first, just to get the plastic to hold together while i
applied the epoxy putty. I like to wrap the putty around the object
as much as possible so it forms a glove like structure, with the part
in the middle. It's really hard to break off like that. I make sure
to allow about 1/8 inch thickness too so the putty is strong when hard.
If it's too thin it snaps off too easy.
I also find that squeezing it into holes in the part to be mended
works great too as it gives the putty a good grip when hard.