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Rustins Plastic Coating, need advice

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AnalogKid

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Tell me please, is it OK for RPC to be soft after ~12 hours? Or RPC will be tough only after a week?
I mix in correct proportion (4:1), temperature ~25-28 °C, surface is wiped with acetone and i apply thin coats with roller. But after 2-3 hours surface is still tacky and fingerprints remains when i press or hold it.
When i mix 3 to 1 (just for experiment) surface dryes faster, but it still soft.
 

Phil Pascoe

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Sometimes it takes a while for the first coat to cure - different times on different substrates. As long as it dries properly I wouldn't worry about it - the second coat should dry quickly.
 

AnalogKid

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Thanks for answer. i dried first coat ~24 hours and it was not tacky. But 2 and 3 were soft.
Also, update. "3to1" coats dries hard after a night.
It looks like hardener is not enough, but I am sure that I mixed in the right proportion (with 5ml syringes, 20ml + 5ml)
Can you tell, how you measure proportion? :)
 

Phil Pascoe

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What do you call "soft"? it would normally be touch dry in a hour or two, sometimes not many minutes, but it wouldn't be properly hard for a few days. What are you using it on?
 

AnalogKid

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Coating wrinkles under fingers, i think it soft :) I use it on veneer, coated with Rustins Wood Dye (lightly rub with fine sandpaper and wipe with acetone before RPC)
Also, i got Rustins support anwer:
"The batch numbers you supplied tell me the hardener is 3 years old, which is roughly how long after manufacture the hardener significantly loses its strength, (although in this regard the rate of lose is a complex variable determined by factors beyond our control, i.e. storage conditions). Changing the mix ratio to 3:1 has helped, but really the hardener needs replacing"
 

Phil Pascoe

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If it wrinkles under your fingers it's too thick - it may well have thickened with age. If you persist with it try thinning it. Was the dye fully dry before you over coated it? - I've found before that sometimes that'll retard the drying even if the dye is compatible, which as far as I know any dye is once completely dry.
 
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