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Author Topic: Shelf life for dope  (Read 550 times)

Offline Fred Quedenfeld jr

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Shelf life for dope
« on: November 28, 2021, 07:53:14 AM »
I just opened a quart can of Brodak clear that was 10 years old  It is 80% hard
Do I have to bite the bullet and throw out $36 worth of dope?
any suggestions 
Fred Q

Offline Avaiojet

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Re: Shelf life for dope
« Reply #1 on: November 28, 2021, 09:09:20 AM »
I just opened a quart can of Brodak clear that was 10 years old  It is 80% hard
Do I have to bite the bullet and throw out $36 worth of dope?
any suggestions 
Fred Q

I would toss it, but that's me.
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Offline Serge_Krauss

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Re: Shelf life for dope
« Reply #2 on: November 28, 2021, 09:45:45 AM »
I've been able to rejuvenate Brodak clear butyrate with thinner, if it was not actually hard, but if it's hard, I think you need to take the loss. I don't know how Brodak's would feel about replacing it, if it had been unopened...

SK

Online Brett Buck

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Re: Shelf life for dope
« Reply #3 on: November 28, 2021, 12:55:05 PM »
I just opened a quart can of Brodak clear that was 10 years old  It is 80% hard
Do I have to bite the bullet and throw out $36 worth of dope?
any suggestions 
Fred Q

  I would just throw thinner in it until it was the original volume, stir it up, and move on. There's nothing tricky about air-drying paint, unless there is some secondary chemical reaction, it's plastic dissolved in solvent, you can dissolve it again with more solvent.

      Brett

Online Ken Culbertson

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Re: Shelf life for dope
« Reply #4 on: November 28, 2021, 02:46:30 PM »
I am 74 and most of me still works so I would say that a Dope with only 10 years on it is OK. LL~

Dope hardens by evaporation of the liquids, not a chemical reaction so if it is not already solid I say go for it.  I have thinned gummy Randolph Nitrate that was in the can 3 years and it was fine.  I don't use Brodak.  First thing I do with dope is to put it into glass containers.  Once you open a can it is nearly impossible to get it 100% air tight again.

Ken
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Online kenneth cook

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Re: Shelf life for dope
« Reply #5 on: November 28, 2021, 05:42:58 PM »
              Fred, I had this happen to 4 qts. Adding thinner is more than likely not going to work and the color of mine was extremely amber. The solids were very hard and  wouldn't soften.

Online Will Hinton

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Re: Shelf life for dope
« Reply #6 on: November 28, 2021, 06:18:10 PM »
several years ago I found an unopened barrel of clear butyrate in a tee hanger that showed an inventory of mopre than ten years.  We were recovering a couple of Colts and needed the dope so we opened it, poured the very thick stuff out into a container and added 50% thinner to it.  We ended up using that entire barrel eventually and all was well.  It was Randolf, by the way.
John 5:24   www.fcmodelers.com

Offline Massimo Rimoldi

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Re: Shelf life for dope
« Reply #7 on: November 29, 2021, 02:43:45 AM »
Hi.

IF the dope contains only Nitrocellulose and / or Cellulose Acetate Butyrate there is no problem (as many have already said) to recover it.
In fact, the original production process involves dissolving dry chips in solvent.
Depending on the solvent we have available and the volume of the mass to be dissolved, the process can be more or less fast, personally I recommend adding a small amount of acetone to the dry product to begin with.
This should soften the dried resin very quickly and facilitate subsequent dilution with conventional solvent.

Massimo


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