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Does two part resin go bad in the bottle ?

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  • Member since
    August, 2013
Does two part resin go bad in the bottle ?
Posted by Putsie on Monday, November 14, 2016 5:30 AM

Hi guys !

 

Does unmixed resin go bad with age?

I have some stuff from micro-mark.....the "A" "B" sort ...and the date on the cap label is two years ago.  I used it recently, mixing as usual one to one, and the parts remained somewhat "flexible" after curing.  Even after several weeks they are flexible?  I was careful to mix one to one, so anyone have any comment ?

I have found that the molding mixtures get hard with age and unusable.  Does that hold for the resin ?

 

THX

 

 

  • Member since
    April, 2004
Posted by Jon_a_its on Monday, November 14, 2016 7:00 AM

In a word... Yes.

but it could also be a reaction to oxidation in the tin, age, humidity, the release agent, the moulds, if it's Monday...

or all of the above, have there been any changes since the last time you used the resin?

  • Member since
    August, 2005
  • From: Mansfield, TX
Posted by EdGrune on Monday, November 14, 2016 8:13 AM

Jon_a_its

In a word... Yes.

but it could also be a reaction to oxidation in the tin, age, humidity, the release agent, the moulds, if it's Monday...

or all of the above, have there been any changes since the last time you used the resin?

Yes,  as Jon indicates it could be anything.  But it is most likely oxidation fro the air.   And two years,  I'm surprised that the resin didn't harden in the bottle and that you were able to mix up a batch.  
 
Smooth-On resin sells a spray which you spray in the bottle to displace the 'bad' air.  See smooth-on.com.  They also have a lot of how-to videos which are informative.
 
I also tightly seal my left-over resin with some wax paper under the lid & around the threads.    I also store it in the beer fridge in the garage to extend the shelf life
  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Monday, November 14, 2016 8:43 AM

I find it can last quite awhile, but the resin does seperate.  One needs to invert the bottle back and forth to remix it.  It is well known that one needs to stir/mix the resin and catalyst together well. It is not as well known that you have to remix the resin itself before mixing together the resin and catalyst.  Someone on this forum clued me to this several years ago, and I have successfully used quite old resin since.

Don Stauffer in Minnesota

  • Member since
    April, 2005
  • From: Baton Rouge, LA
Posted by T_Terrific on Monday, November 14, 2016 6:42 PM

Was the resin as old as you and I are, Don?

Just kidding, now a new question for this subject:

Why does epoxy give up when solvent-glue don't?

Tom TCowboy

“Failure is the opportunity to begin again more intelligently.”-Henry Ford

"Except in the fundamentals, think and let think"- J. Wesley

"I am impatient with stupidity, my people have learned to live without it"-Klaatu: "The Day the Earth Stood Still"

"All my men believe in God, they are ordered to"-Adolph Hitler

  • Member since
    April, 2009
  • From: Lowell City, Mars
Posted by Cadet Chuck on Monday, November 14, 2016 8:52 PM

Does the chewing gum lose its flavor, on the bedpost overnight???

Music  Music  Music  Whistling

Computer, did we bring batteries?.....Computer?

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Tuesday, November 15, 2016 9:36 AM

T_Terrific

Was the resin as old as you and I are, Don?

Just kidding, now a new question for this subject:

Why does epoxy give up when solvent-glue don't?

 

It is a different kind of bond.  Solvent glue really is akin to welding.  The cement melts the surfaces so the plastic actually fuses together. The solvent can eat through some limited amount of contamination on the surface.

Epoxy relies on a true adhesive bond.  With such surface bonding cleanliness is next to holiness.  Also, I have had a harder time with epoxies lately- it seems something is different in the chemistry of the styrene some kits now use.

 

Don Stauffer in Minnesota

  • Member since
    April, 2005
  • From: Baton Rouge, LA
Posted by T_Terrific on Wednesday, November 16, 2016 12:27 PM

Don Stauffer

 

 
T_Terrific

Was the resin as old as you and I are, Don?

Just kidding, now a new question for this subject:

Why does epoxy give up when solvent-glue don't?

 

 

 

It is a different kind of bond.  Solvent glue really is akin to welding.  The cement melts the surfaces so the plastic actually fuses together. The solvent can eat through some limited amount of contamination on the surface.

Epoxy relies on a true adhesive bond.  With such surface bonding cleanliness is next to holiness.  Also, I have had a harder time with epoxies lately- it seems something is different in the chemistry of the styrene some kits now use.

 

 

 

I would say it is both the kit and the epoxy's chemistries have changed.

Kits are typically "soft plastic" as compared with the rock-hard petro-based styrene plastic of the older kits. As I understand, the newer plastic uses a sugar-based product.

I remember when epoxy first came out, one ad showed a full-size car literally suspended in the air by an epoxy bond!

My experience is that for bonding plastic, the newer epoxy is a lot like the old Lindberg model cement sold at the local mom-and-pop store. It didn't bond well, and had a strange amber residue.

The other day, I unboxed a built-up plastic electrical substation structure fora railroad layout, that our big fat cat slept on, caving-in the box-lid, and all the epoxy bonds were broken, and the epoxy residue (which had turned from clear to amber-yellow) was easily scraped-off. Just like the old Lindberg plastic model cement.

Go figure.Whistling

Tom TCowboy

“Failure is the opportunity to begin again more intelligently.”-Henry Ford

"Except in the fundamentals, think and let think"- J. Wesley

"I am impatient with stupidity, my people have learned to live without it"-Klaatu: "The Day the Earth Stood Still"

"All my men believe in God, they are ordered to"-Adolph Hitler

  • Member since
    August, 2013
Posted by Putsie on Tuesday, November 22, 2016 7:30 PM

Hi folks,

 

thanks for all the answers........the idea of putting it in the fridge sounds good.....I use it with super-glues and it does work.

thanks....

 

  • Member since
    January, 2012
Posted by Ausfwerks on Saturday, November 26, 2016 12:56 PM

Urethane resins are so sensitive to moisture that the shelf life is very slim unless real precaution is taken.

The isocyanates in the yellowish component bond immdeiately with the slightest hint of water, that's the crust you get on the container lip and also what happens in your lungs and throat (if you've ever felt the tightness after mixing it).

Refrigeration makes zero difference, keeping it closed as tightly as possible and only opening it for the shortest period you can will prolong it. Smooth-On sells what they call a gas blanket, with is used to get an inert gas into the bottle and drive out the air.

I buy resin in large quantities and have kept it for extended periods be breaking it down from the gallon jugs into smaller units and keeping them in double sealed zip lock bags. 

I measure out the MDI (the clear part), add color, etc. open the iso (yellowish part), measure, close the container, mix, pour, vacuum and while it's getting to 29inches, I seal the bags on the iso. That way there's little exposure and it lasts. After about a dozen pours, the bottom of the inner bag fills with a crust of moisture bonded sand.

I know someone who spilled a gallon the iso in his shop. He thought he cleaned it up, but the next day his aquarium had a plastic crust on the surfae and everything was dead.

The Isocynate is similiar to the one in CA glue, that's why you can accelerate it by exhaling on it. The moisture in your breath sets it up.

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