Gelcoat shelf life

[Frank60]

Hoping this is an easy question. I have a quart of Spectrum gelcoat that's just over one year old. The can says: "shelf life for uncatalyzed materials may be up to 6 months when stored in dry cool areas at temperatures of 60 degrees or less."

Needless to say that I've not met those ideal storage conditions. The gelcoat still looks ok, but I don't want to do a bunch of repairs and find that it doesn't catalyze properly or hold up over time. I'm not sure how to tell if it's still ok.

The can also says that 'gelcoats have limited storage life manifested by hardening in the container'. It's not hardening in the container.

I'm hoping that someone with extensive gelcoat experience can advise me on whether I can still use this stuff. A new quart costs $144 on iBoats. So it's expensive stuff, but it's color matched to my boat and actually matches really well considering that my boat is 15 years old.

Appreciate any advice.

 

[Bacchus]

I dont have extensive experience but would be tempted to mix a small batch and see if it cures properly.

 

[Comodave]

My concern with using it is that if it doesn’t go off properly or doesn’t age well after a while, you will have a lot more work getting it off and new gel on. I know it is expensive but if the manufacturer says 6 months in controlled situations and it is over a year in uncontrolled situation, I would buy new. Your labor is probably worth more than a new quart. Too bad you can’t buy a pint...

 

[Bill V]

Very surprised at gelcoat prices in your neck of the woods. I bought 4 quarts of color matched gelcoat for my boat last May ($188 per gallon), used 1 quart and left the other 3 cans on the shelf in my shop which is heated and temps remain a consistent 55-60* all year. I just finished a project and need to spray the gelcoat and opened up another can. No issues whatsoever with it and results were as good as I could expect.

 

[Sailor of Fortune]

Hoping this is an easy question. I have a quart of Spectrum gelcoat that's just over one year old. The can says: "shelf life for uncatalyzed materials may be up to 6 months when stored in dry cool areas at temperatures of 60 degrees or less."

Needless to say that I've not met those ideal storage conditions. The gelcoat still looks ok, but I don't want to do a bunch of repairs and find that it doesn't catalyze properly or hold up over time. I'm not sure how to tell if it's still ok.

The can also says that 'gelcoats have limited storage life manifested by hardening in the container'. It's not hardening in the container.

I'm hoping that someone with extensive gelcoat experience can advise me on whether I can still use this stuff. A new quart costs $144 on iBoats. So it's expensive stuff, but it's color matched to my boat and actually matches really well considering that my boat is 15 years old.

Appreciate any advice.

If you call Spectrum, I bet they will say go ahead and use it.

 

[tiltrider1]

Gelcoat has a 1 year shelf life per the manufactures. Kind of like food. Just because it has a pull date does not mean it can't last twice that time. Just means the manufacture won't guarantee it after one year. Why spectrum says 6 months? Maybe they add something that has a shorter life. I have a can that is now 2 years old that lives in a wine cooler. I expect it to be just fine but I will do a test sample before I put it on the boat.

 

[DNT99611]

I have used gel coat as old as two years. The problem I have had was inconsistent curing. It is a real mess if you have areas that do not fully cure. And this was fully mixed so that was not the problem. As other have said I would mix up a few ounces and spread it out on something to see if you get good results.

 

[ghost]

I’ve used gel much older successfully. Catalyze a little, you have nothing to lose. I bet it’s fine. If it’s not, it’s a lovely mess, but scrub a dub dub with acetone and you can get it off.

 

[Pete Meisinger]

I used some old resin recently. It had changed colors to a very dark brown. It set up fine and worked out well but it would not have worked in an area of visability. Id get rid of it.

pete

 

[Larry M]

I've had gel-coat stored for 4 years and it work fine. I did have to thin it a bit. If in doubt, Don (Bacchus) had a good suggestion.

 

[Frank60]

Thanks for the replies. I had planned to test it first. I have a feeling though that it will appear to cure properly. My concern was if there's more to it than that, where it may seem like it's cured properly but then not hold up over time.

I'm tending to agree with Comodave that it's probably not worth the risk and aggravation if it doesn't work. I only used about 25% of the quart and did quite a number of small crack and chip repairs. It goes a long way. Hate to waste it, but maybe better safe that sorry.

I've been learning as I go with doing gelcoat. Watched a bunch of videos. It's not that hard to do but finding hard to do well. I've had a real comedy of errors that I thought I'd pass on for your amusement. I had mixing cups that disintegrated with the bottom falling out while I was working. What a mess. Now I got proper cups intended for mixing epoxy. I was using popsicle sticks to stir and ended up with wood splinters in the finish. Now I have plastic stirrers. As I saw on a video, I used an old plastic loyalty card to smooth the gelcoat, and the ink came off the card into the gelcoat. I found out that you need to sand with a block or you get wavy results. For vertical gelcoat, I thicken with silica but continue to have trouble getting that process right. I'm still having trouble getting all of the bubbles out for smooth surface causing me to do a second coat. Anyway, I'm getting better after all those mistakes. It really looks so much easier in the videos.

 

[jleonard]

I've also used gelcoat that was several years old with no problems curing or holding up.
You can use a "cool can" to allow you to be able to brush on multiple coats with the same mixed batch. The cool can will keep the gelcoat from curing.

 

[psneeld]

Read the instructions .....but a tad less hardner I believe also helps along with cooling.

 

[lwarden]

Unless you are touching up very small spots I've found spraying gelcoat is far easier. A cheap spray gun from harbor freight works well and thin with a small amount of styrene monomer and Acetone. A Preval sprayer works too if you don't have compressed air. I've even air brushed it before for very small areas. If you want to get a really good finish and less sanding/polishing cut it 1:1 with Duratec.

 

[ghost]

If you want it to match you pretty much need to spray so you can blend. The preval sprayers are inexpensive and work perfectly. You will have to learn the right level of thin, but same learning curve really as brushing. I start by filling just shy of the surface like you have been doing. Then mask about six inches, or more, around the area and sand to get the sheen off. Say around 120 grit or so. Then spray the repair and let it feather a bit. You can actually build pretty well just spraying, but make sure you did not fill level before spraying. You don’t want that sharp edge. After it cures, sand through the grits, wet sand the finer grits and then polish. If the color was close you will have a hard time seeing it.

If you need to see if the color matches, put some uncatalized gel on the boat and cover with some scotch tape. Fix the color before mixing, usually the boat will be more yellow than out of a new can, so a tiny bit of yellow or brown will make up for the years of oxidizing. Don’t try to be perfect, most won’t notice. The biggest trick is to spray so it blends. If you smooth with a scraper it leaves a perfect surface after sanding it out, but it won’t blend, you will have a line of color change that is easily noticeable.

The rest is practice unfortunately. That’s why good gel coat guys are worth whatever they charge. Compared to a yard guy just learning, my repairs are massively better. The gel guy who taught me, you can’t see his repairs even when he points at them. If you walked by mine and I only told you within ten feet, you would probably miss it 75% of the time.