Do larger amounts of resin have longer curing times? For example, I mix up 24oz of resin which seems to give me about 10-15 minutes of working time for a 6ft board. Now i’m about to glass an 8 foot board and going to use 60oz of resin for the deck. Will I still have a 10-15 minute working time? Or does larger amounts of resin take longer to start to cure? I’m new and not the best glasser so i’m nervous about it gelling up on me before I finish up.
In my experience, no. I’m not an expert, but from the few dozen boards I’ve glassed (epoxy resin) the problem is the longer working time. That’s where you run into trouble when you’re getting into bigger batches & bigger projects. Also, with epoxy resin, it seems to set up faster when sitting in a cup vs spread out on a surface. Temperature, humidity, ratio of mix, there are a lot of factors that can affect set up time. But I have not heard of the size of the batch being a big issue, as long as the ratio of your mix is consistent. I’m sure other more experienced voices will join the conversation. But my initial thought is to plan for a longer working time on a bigger project, and compensate by having more help, or planning your work to minimize any wasted time & motion.
I’m with Huck; theoretically the resin hardens within its time, no matter how big the batch is, but the time depends on the climate conditions and even more on the kind of volume. If a liter badge is spreaded, it will take longer than in a cup. This is value for epoxy, I do know nothing ablut poly.
And usually the most clear epoxies especially those who will stay clear, have the longest hardening times. My epoxy can be worked for almost half an hour, if not more and it takes at least 5-6 hours it is still tacky; after 12 hours I can touch it, really safe is 18hours or more…
thanks for the response, thats a long time for epoxy. Ive only used poly resin, this will be my third board. I just always wonder how people glass 9-10ft long board with such a short amount of working time.
There are videos on YouTube (the ones by pro glassesrs) that can give you a real good idea how an experienced glasser does it. Everything in place at start time, focus, no distractions, no wasted motions.
Ohhhkay, as has been mentioned, the hardening time/pot life should be consistent, and with polyester resin and assuming your resin/catalyst ratios are consistent, they should be.
Epoxy, you can’t monkey with the ratios of resin and hardener to get it to go faster or slower. Instead, most make fast or slow hardeners. If you’re doing production, fast is good, otherwise slower is better.
Polyester. add a little less catalyst.
With both, working on a cooler day, out of the sun, possibly chilling the resin components before mixing ( though this may mess with the viscocity. making it harder to wet out the cloth) will help.
Two more things- most people take longer to mix a bigger batch. That time comes off your pot life and working time. And then, well, resin goes off in an exothermic reaction: it gives off heat as it hardens. The stuff that’s on the glass itself, it’s thin, the heat dissipates. In the mixing container, though, it doesn’t, which makes it harden faster, which gives off still more heat, you see how that goes. Don’t do a dab here a dab there, instead get all it on the board and start spreading, quickly.
All of the above is an equation of the knowledge and experience a professional glasser keeps in his head, all the time.Rather impressive, when you think about it.
hope that’s of use
doc…
They work fast. That’s how!
Thanks understood
Doc used a word that is key, here. Exothermic. Poly and epoxy both create heat as part of the chemical reaction. The greater the mass, the more heat. That will shorten working time all else being equal. So if you are going to mix a larger batch than you’re used to, prepare to work a little faster.
I might have missed it, but it seems you do not state what resin you are using? One advantage with poly is the ability to adjust how much catalyst you use depending on ambient temp and volume. So with a bigger batch you can reduce the catalyst ratio and slow the ‘kick’ time. Epoxy must have a constant ratio.
I may be the only one who finds the use of “cure time” to be inaccurate? Curing is the stabilization process that happens after the resin hardens. It is not the same thing as the short time span a batch is workable. That’s called gel time, the point where a liquid begins to become a solid and will no longer saturate the glass fibers.
Pour.
Spread.
Squeegee excess
Tuck rails
Walk away
I am using poly, I used about 12cc cat for a 40oz bucket. Mixed orange pigment and humidity was HIGH that night. Those factors seemed to help me out a bit. About 15 minutes of working time before it gelled.
im doing a 4x6 deck today. The board is 7’2 x 22. Any recommendation on resin amount I should use? I was thinking 60oz because I’m so new at glassing.
Sooo True.
That seems like a hell of a lot of resin for one side of a 7’2. An online resin calculator I found says that a gallon will do 6.5 sq yds of 10 oz cloth. 60 oz is nearly a half gallon.
The surface area of a board that’s 7’2" x 22 isn’t even two square yards.
youre right… it is… but i get nervous lol. I know its overkill I just dont want to run out
awesome video, thanks for sharing that!
Thank you to all you guys who got back to me. It helped a lot.
He ran dangerously close to running out of time and resin. If you watch he’s scrounging for resin out of the drip tray at the end. With color work you definately want to have a little extra.
The channels add an extra layer of difficulty, and he’s not the fastest or best I’ve ever seen, but there is still a boatload of things a beginner could learn from the video on technique & even the way his racks & workspace are set up. I think it’s good for a beginner or a backyarder like me to watch a lot of these videos & take notes, you’ll start to see the differences between various methods & shop setups, & find stuff you can use, like pulling resin from the drip tray in a pinch.