Gelcoat cure time

So I have a 1990 wellcraft 20 fish that when I pulled the outboard off to do repairs it also pulled the gelcoat off due to the sealant that was used to seal the bolts. I sanded the area and brushed on a thick coat of unwaxed gelcoat then sprayed PVA over the repair. I waited about 24 hours then sanded the repair and realized I still had some low spots so I wiped the area with acetone to add more gel and when I run the acetone over it the gel got tacky and I noticed that it was wiping the gel off.
Did I not wait long enough before attempting to sand and recoat ? The gel seamed to be really hard and sanded good...

Thanks in advance

Mark

 

Gel coat can be affected by acetone if it's not fully cured.

How much catalyst did you add.

And what's the ambient temperature.

 

I only mixed up 1oz of gel and I used 14 drops of catalyst the temp was around 68 the gel started to kick in about 10 minutes so I hit it with pva

 

It is very difficult to accurately measure catalyst ratios when mixing such small amounts of gel coat, and the drop method is poor at best. So sometimes you get it right, and sometimes you don't.

Using a small scale that can be found on Amazon or eBay for under $15 will yield far more consistent results.

And in the lab 100cc of gel coat is the normal amount mixed because it will give repeatable results.

After saying that, leave it sit longer before sanding, another thing to try is buffing before sanding. Buffing it first will heat the gel coat instantly and help it cure more thoroughly.

 

Ok thanks I will pick a scale up for the future.. also when the direction's are instructing to 12 drops to 1oz are they talking 1oz in weight because I was mixing it by volume.?

 

It's close enough either way, the QC lab will go by weight. All the equipment that pumps and sprays resin or gel coat mix by volume.

 

Best practice would have been to fair the repair area before applying the finish.
I use a heat lamp to insure cure before sanding.

 

Ok what exactly does it mean to fair ? I see it mentioned a lot. If you are talking about feathering out the area for repair by means of removing gel and making the place larger i did that as part of the prep work... also I did put a heat light on it after I finished applying it....

 

Wax is really cheap and gets the best results. Otherwise, use a sheet of mylar or other similar material over the repair.

 

Where is a good place to get it because every where I see it's about $16 an ounce

 

PVA works fine, you won't get better results with wax.

 

You already spend more than $16, not counting your time.

 

Oh I agree with that i just thought that when you said it's cheap that you knew of a place it was cheaper

 

Wax Additive Sanding Aid for Gel Coats and Resins https://www.bottompaintstore.com/Wax-Additive-for-Gel-Coat?gclid=Cj0KCQiA1KiBBhCcARIsAPWqoSo4Ov43jBnSfHbZ8VZfccMLn0xcdrOyCWy4gSrHZszWkj3PEcjsBXQaArlmEALw_wcB

 

Yes sir that is definitely cheap enough