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Drying PVB + red gum bound stars


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Posted (edited)

Intro for moderators: I've made a mistake, this has nothing to do in the tools and tooling section, would you be so kind to move it please?

Hi all. I've been making some stars (kp, al flitter, ti sponge, red gum) and bound with PVB and isopropanol.

Contrary to other PVB isopropanol bound stars they seems to be drying VERY slowly. After 3 days under the fan, they are like little chewing gums: a more or less hard crust on the outside and inside still very soft. They can be squeezed easily, and when "opened" the consistency is just like after mixing. The outer crust has gone airtight! Does anyone knows, or already had this experience? if I can catch-up this, or if my batch is just ruined... Thanks in advance.

Edited by Sulphurstan
Posted

The redgum is to blame. Once to wet the stars are easily driven in.

Redgum sucks.

 

PVB alone is not so problematic, but when RG is around, be careful with the solvent. Use a scale or a graduated cylinder, dont just dump it in your comp...

 

Never try to accelerate the drying processs. If you use pure isopropanol the stars should be dry in few days at room temperature.

 

 

Posted (edited)

Thanks Mabuse.

Ok, that make sense, i just sprayed the isopropanol "at guess", stir, comp looks dry..., spray more, stir, comp still looks dry... spray again, stir.... and then very suddenly the thing became super soft, and I thought to myself "oups looks like I have sprayed to often, the RG has dissolved!!".

 

I will probably dispose of this batch, and make VERY little addition of isopropanol, stir long time, before adding little more IPA and so on..

Just throwing 100 grams of comp away, hate that 😵👹 but it's a lesson!👏

Edited by Sulphurstan
Posted

Dry alcohol bound stars in a cold dry enviroment. I had the same issue aswell, the outside becomes hard en blocks the alcohol inside the star from evaporating.

 

I wouldnt dispose them. They will become hard someday, it just takes a while now. Atleast 1 week from now, maybe even longer. Throwing them away will undo your hard word :/

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