Primer pot life warning

[Noklin]

Hopefully this will keep someone else from making the same stupid mistake. I mixed up the two part System 3 primer this morning, thinking that I knew the instructions on application. I had read them several weeks ago when the primer arrived and did not take the time this morning to ensure that what I remembered was what it actually said. I was in no hurry so after applying two coats I broke for lunch. Before I could complete the third coat the primer kicked off in the roller pan. Upon looking at the primer in the can it looked like wet cement. After this expensive mistake, I read the instructions and found that the pot life was only 4 hours at 77F. It was 83F today with a 90F heat index and rain off and on all day. As the instructions warned it kicked off in a little less than 4 hours at this temperature. I loss about a quart of primer.

[Ray Frechette Jr]

If it makes you feel better chalk it up to cheap tuition.

A qt costs maybe $20.00

A week of tuition at Wooden boat would cost several hundred at least...

Once you factor in lost wages and transportation well over 1.5 K.

[Greg Luckett]

If it makes you feel better chalk it up to cheap tuition.

A qt costs maybe $20.00

A week of tuition at Wooden boat would cost several hundred at least...

Once you factor in lost wages and transportation well over 1.5 K.

Well said, Ray, and a very good point.

Noklin, I think all of us have had similar learnings....

Don't feel too bad about it. I nearly blew up a quart of 2 part Interlux a few years ago, that I had put the top back on the the can after using about 1/2 of it, then sat under a tree  to wait for the first coat to dry a bit, then nodded off, woke up to the can's hissing and it had bulged too. I kept my distance until it quit hissing and smoking. Fortunately it was sitting out in the yard away from things that it might have harmed. Now I only mix the amount I need for a coat at a time.

[Ray Frechette Jr]

Neat,  Paint the boat in a hurry A LA Mr Bean!

[Ken_Potts]

I still remember the first time I saw epoxy smoking while it melted the pot on a summer day 

[Maria CS20 104]

:shock:  Hey folks, I too have had cook-off while working with the epoxy and some primer.  Here in North Central Louisiana it gets HOT and when it's over 90 F, it means work quick in small batches.  Sometimes 4 tablespoons epoxy to 2 tablespoons hardner, and even this isn't going to prevent it from cooking before it can be completely used.  Most of the time, I will spend two to three hours laying out work path, cleaning sanding and scrapping, wiping down with acetone, setting up necessary layout of tools, gloves ect for three or four areas I will be working on, one after the other.  WHen the shop is organized and I am organized I set up mix stations near my work areas on the boat.  I have had as many as four setup at for one afternoon.  I then go station to station and mix, precoat the areas to fillet, thicken with wood dust and fillet.  6 tablespoons go a long way using tounge depressors and scrapping up overage and using it to complete a section of the fillet.  I always have three of four bullet leves and a four foot and six foot precision level in place on the boat when I am filleting and fiberglass taping.  BEfore I start at a work station I check every level to ensure level and plumb.  I usually am leaning against the hull or have to be inside with my fat backside swinging around.  Once the set is dome, I stop and check that it is still in line (when I am outside the boat), I have had to adjust the level several times once I finish in one area before I go onto the next work station.  It also make me more cautious about leaning on the hull and moving the boat.  Once all work stations are finished, I go back and check the levels again, and I have to adjust about half the time.  I also found that once the fillet is in place is seems to slow the cookoff and I have not had to grind any out and redo the work.  I have however had a few batches cookoff in my hand when I was using heavyer gloves or got a real mess going where I was filleting, I once put down the batch cup and came back to a melting smoking little caldron sitting usually in an inappropriate place, like the hull bottom, or on top of a work piece.  One actually attached itself to the bottom of the boat when I had become totally distracted as the mix I was installing started to cook into lumps as I was laying it in.  Had another I had knocked over melt into the top and across the toe of my boot as I worked, it fell off the 2x4 I had set it on, I bumped it and it landed right next to my foot and spilled against and across the boot in a big lump, it got warm, the smoking toe of the shoe scared me a little too, ( the toe melt was a larger batch of about 3/4 a cup in 95 degree weather, earlier in the building when I was filleting the inside of the hull after stitching), didn't take me long to realize smaller batches were better to work with.  Many lessons learned, Many more to learn as we are at turnover of the hull and we begin the fairing and priming and painting and of course the sanding and sanding and sanding and sanding and sanding.

Jim

[Dogdad]

:shock:  Hey folks, I too have had cook-off while working with the epoxy and some primer.  Here in North Central Louisiana it gets HOT and when it's over 90 F, it means work quick in small batches.  Sometimes 4 tablespoons epoxy to 2 tablespoons hardner, and even this isn't going to prevent it from cooking before it can be completely used. 

You're changing the mix ratio to slow hardening?  Does the epoxy manufacturer say that's OK?  Most sell a slow hardener for hot weather.  Changing ratios is usually not reccomended because it alters the properties of the cured epoxy.

[Gordy Hill]

Here in Orlando I learned early on that "slow" means fast, and "fast" means now. I noticed the batch getting warm even before it was fully mixed. I put it in the freezer for just a few minutes till the warm feeling was gone. I try to keep all my epoxy and hardener as well as mixing tools in air conditioning at least a day before mixing it. Then I mix it and still pop it in the freezer for a few minutes. The batch stays cool much longer, but as soon as it's spread it changes to ambient temp.

I haven't noticed any problems other than some epoxy on the handle of the freezer door.

Did I mention I'm single and live alone?.....

[Maria CS20 104]

I'm using the 2 to 1 mix ratio and slow does mean FAST sometimes VERY FAST in the warm weather, Really fast as it can begin to cookoff as you mix it up in the cup.  I use CHEAP plastic 8 oz. clear drink cups, I have a few marked to the mix levels as template cups and set them inside the ones I will use and mark the outside with a sharpie marker, making sure I account for the difference in the bottom of the cup as they do not stack but within about 5 32nds, a red hair more than 1/8 inch.  I actually measured it "like it matters"  I can't pour that well and the pumps are pumps.  I did get to getting a bowl of crushed ice and a little of water to set larger cups of batches in when I was mixing a half cup or more in outside temperatures over 85 to reduce cookoff time and that seemed to work really well.  The stuff does not seem to stick to cornell ware so far, but Don't tell my wife.

Jim

[Greg Luckett]

Here in Orlando I learned early on that "slow" means fast, and "fast" means now. I noticed the batch getting warm even before it was fully mixed. I put it in the freezer for just a few minutes till the warm feeling was gone. I try to keep all my epoxy and hardener as well as mixing tools in air conditioning at least a day before mixing it. Then I mix it and still pop it in the freezer for a few minutes. The batch stays cool much longer, but as soon as it's spread it changes to ambient temp.

I haven't noticed any problems other than some epoxy on the handle of the freezer door.

Did I mention I'm single and live alone?.....

Here in Michigan, I do just the opposite. Keeping in the house for a few days to warm up the epoxy, then keeping a heat lamp on the cans while out in the shop.

[PeterP]

Sounds like you need to switch brands. I use Graham's Slow and it gives more than ample time at 85-90 deg here in NC. Raka also works well here. They are both 2:1 by the way. When you mix a batch use a big pot and spread the stuff up the sides. Even a large batch spread thin will not cook off. I personally like large yogurt containers - they are reusable and already paid for.PeterP

[ChrisObee]

Sounds like you need to switch brands. I use Graham's Slow and it gives more than ample time at 85-90 deg here in NC. Raka also works well here. They are both 2:1 by the way. When you mix a batch use a big pot and spread the stuff up the sides. Even a large batch spread thin will not cook off. I personally like large yogurt containers - they are reusable and already paid for.PeterP

I use the bateau marine epoxy and the medium hardener gives a reasonable pot life at 85 degrees.  Above 90 it gets a little brisk but I could have gone to the slow....

[Maria CS20 104]

I think I am using the slow, and I don't like Yogurt so the clear cups will be my preference.  I SUSPECT THAT WHEN IT'S 85 TO 90 OUTSIDE it's about 10 degrees warmer in the carport, especially when there is no air moving about, sure feels like it

Jim

[Greg Luckett]

I usually use West Systems with the fastest hardner, which works well until it get into the 80s here. I rarely do more than 4 squirts at a time. Once the temperatures get into the 80s and above I shift to the slow hardner. Sometimes I push my luck and use the fast and then do not work fast enough, but I do not lose much when that does happen. I like the work to set up as fast as it can, and the slow hardner takes forever unless it is hot.

My next project will be using epoxy from B&B, and will probably be a couple of Divas this winter by the boys. They want to start using them on the river once the ice melts in the spring.

[PAR]

Spread out you epoxy as soon as it's mixed. If you leave in in the mixing cup, it will kick very quickly. Spread it out on a plastic cookie sheet or other large, flat Tupperware type of container. It shouldn't be more then a 1/16" thick anywhere. This will dramatically slow the thermolidic reaction. In fact, mix your fillers into the spread out mixture too, which offers a lot more surface area to mix with. The confines of a mixing cup will make the mixing task take longer and risk kicking off the goo.

Know your products. Slow is slow, fast is fast, extra slow is extra slow. Just about every formulator will give you a fair guide to the general working temperatures you should use their goo in. Putting goo in a freezer will slow the reaction, but it also decreases the viscosity, making it useless for a wet out, substrate penetration or fiber saturation.

I've never heard bad things about the stuff Graham is selling (happy 25th BTW) and the epoxy Joel over a Bateau.com (Boat Builder Central) also works well. Both of these are substantially less then the major industry "players". Bateau's slow epoxy has 20+ minutes pot time in 90% heat which is fairly impressive and comparable to a West System 206/105 combination. West 209/105 will offer 45 minutes in 95 degree heat.

[Tom Lathrop]

When it's hot and yes it does get hot in NC, I use the cooling box in the attached drawing if the mix is not to be used immediately.  A Solo 9oz cup works well to hold smaller mixes.  Just put in a mix of ice and water and so that the epoxy is immersed and it will prevent it from kicking off with plenty of time for most jobs.  This has worked for me and saves a lot of lost epoxy.  For larger batches, make a larger box.

I also have a small bar fridge under the bench that I picked up for $30 at a garage sale that is used to keep left over epoxy and 2 part paint for later use.