JeffHs
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| posted on 12/1/12 at 10:59 AM |
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Resin won't set?
Does polyester resin or catalyst hardener deteriorate with age? I've got some old stuff that didn't seem to set as I expected last time I
used it, but it wasn't in a critical application so I covered it with filler and forgot it. I need to do a repair that matters so yesterday I
did a trial mix of about 2 parts resin to 1 part hardener. !8 hours later (in a cold garage overnight) it is still not hard, but has reached a rubbery
cheesy state. Should I throw it away and buy new?
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snakebelly
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| posted on 12/1/12 at 11:03 AM |
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Are you sure you're using the right catalyst?
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Toprivetguns
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| posted on 12/1/12 at 11:04 AM |
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It may of expired or the temperature in your garage was too cold. Resins need a certain ambient temperature to cure. .
Try bringing it inside and see if cures properly.
Only drive as fast as your angel can fly... !
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snakebelly
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| posted on 12/1/12 at 11:23 AM |
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Is it definately polyester resin? If so your not using the pink hardener in a tube are you?
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twybrow
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| posted on 12/1/12 at 11:27 AM |
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Very unlikely to be too cold to go off in that time, even in Derby!
And your mix is completely OTT. Polyester typically uses a ratio 0f 100:2 so 2:1 will in itself not exacly be ideal...!
But yes, the resin can take on moisture, and the catalyst degrades over time... try a mix at the correct ratio (assuming you are referring to a
polyester and catalyst, and not an epoxy and hardener - they are not interchangeable!). Most hand laminating polyesters will go off in the pot after
no more than an hour at a 2% mix. If you spread them thinly, they will take longer, and if you completely alter the ratio, that will also have an
effect (you can increase the catalyst ratio to about 10%, but you should get a very fast reaction, and greater exotherm and shrinkage - best to stick
to the specified ratio).
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jossey
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| posted on 12/1/12 at 11:35 AM |
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In my garage in the cold a few weeks ago i mixed up the catalyst with my polyester resin about twice the strength in +3 degree heat and it dried in
3-4 hours....
I guess your using the wrong catalyst. i dont think it expires i have left it open for 3 or 4 months in the past and it just hardens on the top like
an ICE layer....
Thanks
David Johnson
Building my tiger avon slowly but surely.
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JAG
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| posted on 12/1/12 at 11:58 AM |
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In my experience old Resin and Hardner (Polyester) usually hardens faster as it ages - not slower.
I suspect your mixing ratio has caused the problem 
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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JeffHs
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| posted on 12/1/12 at 12:01 PM |
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I'm using the right stuff - Polyfibre resin and catalyst bought together from a specialist. As I said, its old but both look to be in perfect
condition.
I've just mixed up another small batch using more sensible proportions, so I'll let you know what happens.
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spiderman
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| posted on 12/1/12 at 12:08 PM |
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Too much hardener, will make it a rubbery, try the correct ratio and it should be fine.
Spider
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Paul_C
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| posted on 12/1/12 at 01:05 PM |
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Polyester resin setting
It could be age but it could also be temperature.
My hairdryer was never the same after being used to warm up some lamination but it did the trick.
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NS Dev
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| posted on 12/1/12 at 01:38 PM |
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Almost certainly too much hardener, that is waaaaaay too much, and will stop it curing properly.
I have some resin that is 6 years old and went down to minus 16 deg c last winter and it still cures fine.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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Phil.J
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| posted on 12/1/12 at 03:14 PM |
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I'm with JAG. I find that old resin sets very quickly compared to fresh stuff.
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JeffHs
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| posted on 12/1/12 at 04:37 PM |
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Thanks for advice guys. Batch 2 mixed with proper proportions has set properly.
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