posted 03-11-2004 09:49 AM ET (US)        

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I just finished doing some minor repairs to my 17' Montauk and the [resin] has not gotten hard yet after 2 days. I know now that I did not put enough hardener in the resin. Is there a way I can still get this stuff to harden or do I need to remove it and start again?? It is very tacky right now.

Thanks,
Jeff Kubu

posted 03-11-2004 11:59 AM ET (US)            

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Jeff,

I have a lot of experience with glass. If you used some hardner and mixed the resin thoroughly, it will harden eventually. If the temperature is below 50 F where you are working, put a heat lamp on it and try to force dry it. additionally, you can mix a hot batch of resin (more hrdner than normal (not too much) and wet out the top of the repair. The tacky surface under the hot coat will harden pretty quickly. let that dry and sand/grind it down a bit until you hit tacky resin and repeat the process. at this point you should be able to finish the repair with resin that you have measured the appropriate amount of hardner. By the way, don't add a lot more hardner than is necessary either because the same effect occurs. The resin wil set up quickly and get hard but will remain tacky for a long time. Try the heat lamp. I bet it will harden pretty fast once it gets hot.

posted 03-12-2004 05:35 AM ET (US)            

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[Changed TOPIC; was "Not Enough Hardner (sic) in Fiberglass??"]

I have edited this thread to change the word "fiberglass" to 'resin". Fiberglass is a term for the composite material formed by combining resins and woven cloths.

You do not say what type of resin you were using, but it appears that one can make the assumption it was a polyester resin, not an epoxy resin.

Polyester resins are cured or hardened by addition of a catalyst which encourages the chemical change needed to produce the cure. As mentioned above, if the catalyst was added in too small amount, the reaction rate may be rather slow. It can be nursed along and encouraged with heat.

Some polyester resins do not like to cure to a hard finish if exposed to air. This may be ameliorated by covering the exposed surface with Poly-vinyl Alcohol (PVA). I believe you can also use something like Saran-Wrap to temporarily cover the surface of the resin until it cures.

Epoxy resins are completely different in their chemistry, and are made by combining reagents (usually called "resin" and "hardener") in very precise proportions. If a batch of epoxy resin has been improperly mixed with incorrect proportions, a portion of one of the reagents will remain unused in the chemical reaction, with the effect that the resultant batch of resin will be weaker and possible not harden. Heat will increase the reaction rate of epoxy, but if you have made a lousy batch it will never totally "cure" because it is contaminated with the excess reagent that was not used in the reaction.

posted 03-12-2004 03:59 PM ET (US)            

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I have not tried the heat lamp yet. Nor has it had any direct sunlight. I have been working in my garage which is staying right above the recommended 60 degree mark. I really apprec. the advise and will try everything.

Thanks,
Jeff Kubu

posted 03-15-2004 04:01 PM ET (US)            

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Had some similar problems with a few of my repairs. As the previous post stated it will eventually cure. Mine took several days (5-7) but it finally cured.

I personally think this slow cure makes for a stronger finished product. Comparing these slow cure repairs to ones that cured much faster it seems like the faster cured repairs were more brittle.

posted 03-15-2004 04:15 PM ET (US)            

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I put my boat out in the sun today and the repairs dries solid in a matter of hrs. I think it was a combination of maybe not enough hardner and the temp. being just above 60 degrees in my garage.

Thanks for the help and comments !!