Why o why will my gel coat not dry, I’ve done everything that they said....

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Homer J

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Well I was very pleased with the title but less pleased with the result.
Sunday pm - sanded scratches, acetone to remove grease, mixed gel coat with 2% and double checked. Applied.
Monday pm gel coat still tacky. Phone supplier- they said exclude air, I said thanks for not putting that in the instructions, now what do I do?
They said apply a new coat over the top and clingfilm. Well I went to town to exclude air contact, clingfilm and lashings of exterior masking tape.
Today took off a patch to test and it’s still tacky

what went wrong? It’s not the hardener I checked about 15 times and was really accurate

so - too cold?
or something to do with the first coat

what should I do now? If I have to start again how do I remove the still tackygel coat?

why did I think it should be easier than this? Lucky we now all have weeks to resolve it, if not the funds to do it.

i have plenty of bog roll and antiseptic spray of anyone would like to tackle it for me with payment in inflation proof currency.
 
Gelcoat only goes solid in the absence of air - it's designed to be the layer at the bottom of the mould underneath all the layers of reinforcement.

The stuff that looks like gelcoat but is designed to be used in the air is called 'Flowcoat' or Topcoat, amongst otherthings. It's essentially gelcoat but has liquid wax added to it in about the same quantity as catalyst. You can buy the wax separately and add it to gelcoat.

The confusion between the two finishes isn't helped by 'gelcoat repair' products being sold as 'gelcoat'. But you use Flowcoat to repair gelcoat.
 
I bought a gel coat repair kit from a well-known name. On the second coat i did exclude all the air but still no joy - what now?
 
Motor_Sailor said:
No because you seem to want us to play a guessing game - what brand are you using, whats the job, how did you apply it, etc?
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what guessing game? I have said exactly how I applied it apart from using a brush. I don’t really want to name the company as I suspect it is user error not the manufacturer.
I used it to cover some scratches in a GRP hull of a speed boat. Let me know what else is needed.
The products I used are brand new and used as per makers instruction, with the exception that they neglected to say that it did not contain wax and should have air excluded. When I called them they said to apply another coat and exclude air, which I have done.
 
Homer J said:
what guessing game? I have said exactly how I applied it apart from using a brush. I don’t really want to name the company as I suspect it is user error not the manufacturer.
I used it to cover some scratches in a GRP hull of a speed boat. Let me know what else is needed.
The products I used are brand new and used as per makers instruction, with the exception that they neglected to say that it did not contain wax and should have air excluded. When I called them they said to apply another coat and exclude air, which I have done.
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I suggest you take it all off with acetone, give East Coast Fibreglass a call, tell them what you're trying to do, & they'll sell you what you need & advise you how to use it.
 
Homer J said:
How long should I expect it to take to cure in current temps?
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Homer J said:
what guessing game?
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Whatwere temperatures ? We don't know where your are so cannot even make an intelligent guess.

There are several reasons for a slow or incomplete cure including low temperature, under-catalyzation, high levels of moisture and humidity or even insufficient film thickness

Did you ensure that the substrate temperature was maintained several degrees above the dew point ?

Maybe, If it is only the surface which has not cured you can rescue the situation by rubbing down with fine wet& dry followed by rubbing compound before wax polishing.

BTW mixing proportions for polyester resin and catalyst are not critical like they are for epoxy resin.
 
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AngusMcDoon said:
I suggest you take it all off with acetone, give East Coast Fibreglass a call, tell them what you're trying to do, & they'll sell you what you need & advise you how to use it.
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Watching the video on their website could be very useful
.
 
If you can put up with the smell perhaps make up a small test panel and keep it in a room where the temperature is at least 18C. Make sure the can of gel coat is also at or above that temperature. The panel could be glass or melamine covered chipboard etc.
After application, gelcoat should be tack free (but not hard) several hours later.
Major retailers of gelcoat, such as ECF, often recommend making a test panel first, especially in marginal conditions or where the gelcoat is old. It definitely has a shelf life and although new to you perhaps the can is old?
Re-reading your posts I see you bought a gelcoat repair kit - what temperature range did the instructions specify? My very limited experience would suggest that it is not warm enough at this time of year.
 
If it is just a small area such as scratches and you are not trying to colour match then plastic padding white gel coat repair is fine. I used some at the weekend in 11 degrees C and it went off in 10 minutes and was sandable in an hour. It or it's equivalent can be found in most chandleries.
 
I had a not dissimilar issue using flow coat on the inside of the hull a few weeks back. I ran the heating inside but was too cold and damp so the stuff pickled and refused to cure.

I left it alone for a week, during which there were warmer and dryer days, by the end of which it had hardened properly and I was able to scrape it off like old flaky paint.

The same day I also coated one side of some wood at the time and a very small region of the wood was damp. The resin there refused to cure until the wood had *fully* dried out but the bulk cured perfectly.
 
Homer J said:
I bought a gel coat repair kit from a well-known name. On the second coat i did exclude all the air but still no joy - what now?
Click to expand...

I had this with my Rib last year, don't wash it out with acetone, The solution is actually very simple.

Is the job flat? My hull was upside down which made it easier.

Paint over the new gelcoat area with a thick coat of standard PVA, mine (red hull) went white and looked awful. I left it until I could no longer stick my thumb nail into the gelcoat and scraped/washed off the PVA. The finish wasn't great because I had been trying cling film and parcel tape which didn't work and messed up the job.

Once it was clean of the PVA I sanded it down and repeated the process to get a proud finish that I sanded flat and polished up. The end result was very good.

The above is a good solution - good luck,
 
I purchased gel coat from same supplier with no problems but you could try warming it up with a hair drier or heat gun but be careful with the heat gun not to get to close. You just want to warm it , not cook it. when I first left school ( long time ago now) I worked for a glass fiber laminating company and that’s what we used to do. BTW too much catalyst will inhibit it too so you need to get quantity right although it sounds like you have. Also BTW Methylethylketoneperoxide is not nice stuff so be careful.
 
Thanks all. I think the temperature is the key issue. I’ll leave it covered for another 48 hrs then will try the PVA suggestion. Thank you
 
I had same problem a couple of years ago. It never cured. It was flowcoat so no problem with air, but when it wouldn't set I covered it over just in case and it still wouldn't go off. I suspect I used old hardener. Never had that problem before even in cold weather.
 
Motor_Sailor said:
Gelcoat only goes solid in the absence of air - it's designed to be the layer at the bottom of the mould underneath all the layers of reinforcement.

The stuff that looks like gelcoat but is designed to be used in the air is called 'Flowcoat' or Topcoat, amongst otherthings. It's essentially gelcoat but has liquid wax added to it in about the same quantity as catalyst. You can buy the wax separately and add it to gelcoat.

The confusion between the two finishes isn't helped by 'gelcoat repair' products being sold as 'gelcoat'. But you use Flowcoat to repair gelcoat.
[/QUOTE
Sorry but wrong, my gel coat repair of several square meters was done in the yard in Pwllheli, mix, apply, sand etc!
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