Cold temperatures and vinyl-ester resin

[Wind River]

Originally Posted by Wotname

Get a UV light on to it - that will speed it up big time - at least it does for poly and epoxy so I am assuming vinyl will be the same.

By the way, what the manufacturer say about max catalyst ratio and temperatures???

The absolute minimum catalyst was .75% if measured by weight. If less is used the resin does not cross link correctly and may not cure.

I never used less than 1% and when trying to wet out a large area in 80+ degree temps, there simply was not enough time to work the resin into the glass and roll out the air bubbles. Specs gave 22 minutes before gelling but I saw about 15 minute gel times (in 80+ degrees) and only minutes after that before it was hard enough that it was too late to try to remove the layer.

Trying calculate catalyst by measuring is probably fine if it is a large batch, say 2 quarts or so. Many times I would be mixing a small batch of resin. 5 ounces at 1% is .05 ounce of catalyst. Maybe a very small calibrated syringe might work here but I found the catalyst attacked the rubber plungers in the syringes I used and I ended up throwing them away after a couple uses.

[GILow]

Originally Posted by Wind River

Maybe a very small calibrated syringe might work here but I found the catalyst attacked the rubber plungers in the syringes I used and I ended up throwing them away after a couple uses.

Yes, I had the same thing with the polyester resin, which, I THINK, has the same catalyst.

[Wotname]

Originally Posted by GILow

Thanks guys. I am being (unusually for me) careful with this job. My supplier specified 2% by weight, so by weight it is.

Of course, my maths may be a bit erratic thanks to the fumes, but I THINK i am getting the numbers right. The problem is, each time I have to put the pot on the scales to zero it. Then, remove the pot from the scales, decant from the 20kg tin into the pot, return the pot to the scales before they reset, THEN do the maths to calculate 2%, add that to the number on the scale and pour in the catalyst from the small bottle.

All this gets a bit hard when the fumes get me.

............

I reckon your maths (or at least your arithmetic) will be spot on and way better than mine .

I dunno what qualities you are mixing at a time but I have found easier if I first decant the resin from the big tin into a 5 litre plastic container that has screw top (like an oil container) - I used an old acetone bottle. This makes pouring out a measured amount of resin so much easier. You can either mark the sides of the container or use a measured mixing container. For storage just keep it in dark spot i.e. away from UV.

For poly, I use volume measurements as it easier (for me) to measure the catalyst. Do the conversion once (weight to volume). I have been using a small plastic syringe without issue but I have only put maybe 200 ml though it. I also have a 3 ml glass straight sided lab beaker / flask as back up - cheap as chips from china

I only work in 100 ml (or 100 gram) steps for the resin so the maths stays easy - fumes or not!

[GordMay]

Interesting paper on the subject: “Technical Research - Proper Cure of Vinyl Ester Resins”
➥ https://www.interplastic.com/UserFil...Esters5_07.pdf

[Fore and Aft]

GiLow how about screwing a fan heater to a piece of 4x2 then rotating it so the fan heater blows straight into keel? Here in Queensland where it’s way hotter I do that with a pedestal fan just so I can keep the fumes from burning my eyes.
Cheers

[GILow]

Originally Posted by Fore and Aft

GiLow how about screwing a fan heater to a piece of 4x2 then rotating it so the fan heater blows straight into keel? Here in Queensland where it’s way hotter I do that with a pedestal fan just so I can keep the fumes from burning my eyes.
Cheers

What a great idea, thank you.

Yeah, the stuff is NOT kind on the eyes, is it?

I was wondering if blowing air over it might cause some problem where it blew off critical parts of the catalyst, but clearly, from your experience, this is not the case.

I will do exactly as you say and pick up a cheap and nasty fan heater from Bunnies tomorrow.

Of course, if the boat burns to the waterline... it was probably TOO cheap and nasty.

Edit: I do also have one of those hot air paint strippers that I had considered using, it was what made me ponder the possibility that I might accidentally disrupt the curing process by "blowing away" some part of the catalyst. But a fan heater is just way way better.

[GILow]

Originally Posted by GordMay

Interesting paper on the subject: “Technical Research - Proper Cure of Vinyl Ester Resins”
➥ https://www.interplastic.com/UserFil...Esters5_07.pdf

And I was wondering how I would get to sleep tonight...

That should do it.

Seriously though, thank you Gord, that looks like seriously relevant stuff. I am mid way through studying my masters so I am all geared up for that kind of academic paper.

[Squanderbucks]

Nothing wrong with tanks built integral with hull. Be sure to add additional MEK to the mixed resin. When temps get down into the 40’s best to wait for warmer weather if you can’t raise the temp artificially.

[GILow]

Originally Posted by Squanderbucks

Nothing wrong with tanks built integral with hull. Be sure to add additional MEK to the mixed resin. When temps get down into the 40’s best to wait for warmer weather if you can’t raise the temp artificially.

Hi again. I you and I had this discussion a couple of years back when I was making the diesel day tank and the panic-police were all telling me I was going to die. I still laugh at your login name in the context of the size of your fuel tanks.

We are both still here so it sounds like our diesel fuel tanks haven't killed us yet.

Yeah, I am wishing I could wait for warmer weather for all this, and I may be forced to if I cannot solve the heat problem. But I sincerely hope not because it would stuff up all of my plans for the remainder of the year. I am hoping to get the interior fitout finished in time to move aboard in November, and of course the tanks are the job that really needs to be done first.

Fingers crossed that Fore and Aft's idea works. Cheap experiment, I can get a 2400 Watt fan heater for $20.

As for the additional MEK, the distributor did not suggest that, he was adamant that I stick to 2% by weight when I phoned him to talk about the temperature problem. Maybe it depends on the resin? Could it by a vinyl vs poly thing?

[Wotname]

If you are doubtful that a UV source won't promote rapid cold curing, try an quick and dirty trial.
Get a UV lamp like this one from Bunnings https://www.bunnings.com.au/gecko-50...-lamp_p3340304 , lay up two sample bits, keep them both cold but expose one of them to the UV source.

[Wind River]

Originally Posted by GILow

Fingers crossed that Fore and Aft's idea works. Cheap experiment, I can get a 2400 Watt fan heater for $20.

As for the additional MEK, the distributor did not suggest that, he was adamant that I stick to 2% by weight when I phoned him to talk about the temperature problem. Maybe it depends on the resin? Could it by a vinyl vs poly thing?

Keep your catalyst away from the heater. I was told it becomes very unstable around 150 degrees and and explosive around 230 F.

I was told the same thing about not going over 2% catalyst.

The heater will work fine. I did some hole patching in my hull when it was below 60 degrees so I set up a 500 watt halogen work light about 24 inches away from the patch. It warmed the area quickly and as soon as the resin started to kick, it will create its own heat and will cure without any more external heat.

[GILow]

Originally Posted by Wotname

If you are doubtful that a UV source won't promote rapid cold curing, try an quick and dirty trial.
Get a UV lamp like this one from Bunnings https://www.bunnings.com.au/gecko-50...-lamp_p3340304 , lay up two sample bits, keep them both cold but expose one of them to the UV source.

Great idea, AND I can get a suntan while I am at it.

[Fore and Aft]

That made me laugh GILow, I am imagining you all oiled up in leopard print budgie smugglers fiberglassing your keel.

Cheers

[GILow]

Originally Posted by Wind River

Keep your catalyst away from the heater. I was told it becomes very unstable around 150 degrees and and explosive around 230 F.

I was told the same thing about not going over 2% catalyst.

The heater will work fine. I did some hole patching in my hull when it was below 60 degrees so I set up a 500 watt halogen work light about 24 inches away from the patch. It warmed the area quickly and as soon as the resin started to kick, it will create its own heat and will cure without any more external heat.

That's promising?

What do you think about Fore and Aft's idea of the blower style heater?

I liked the idea because of the fumes issue, but I was worried that there might be some adverse effect by blowing away the boundary layer of chemicals? Fore and Aft has clearly been happy with it, but would you go with his approach or your spot heating approach?

Or both?

[GILow]

Originally Posted by Fore and Aft

That made me laugh GILow, I am imagining you all oiled up in leopard print budgie smugglers fiberglassing your keel.

Cheers

OMG, how itchy would THAT be?

And how do you know so much about my underwear?