heating poly resin to thin it out before lamination. should vary the amount of catalyst?

General Discussion
1

hey.

It seems that i’m about to ask something everyone knows, because I could not find much about it in the archives.

I was watching some videos of pro glassers on youtube and notice how liquid their resin seems to be when they lam. Specially notorius on the drops that fall from the hanging cloth of the free lap.

I know you should avoid getting at this dripping state of the resin by adding too much styrene. 

I’m reading about heating the resin but no one mention what to do with the catalyst in those situations.

I guess I would heat it until I reach the right density. 

But then, how do I calculate the catalyst percentage not to mess up with my working time?

It is starting to get cold down here in the south. I usually heat up the room to work around 65 degrees and I use the Greenlight Polyester resin additive chart as a guide.

well… 

I hope this question is not THAT stupid.

thanks in advance

2

You should be shooting for resin temp.  My choice would be 75-80 F.

The resin will flow and mix better as temp increases.  Catalyst will react faster with resin, the warmer it gets.

I would use the same amount of catalyst you would use glassing at those same temps during the warmer months of the year.

3

Don’t heat Poly resin.  The reason you didn’t find your question in the archives is because nobody in their right mind puts Poly resin in a micro wave.   That is something that is only done with Epoxy.  You can heat Poly resin by bringing it up to room temp.   And room temp should be 70 degrees.  You bring it up to room temp by heating your room and leaving your resin in the room for a few hours before glassing.  Nobody Heats Poly.  if they do;  they really shouldn’t.  You’re going about it ass backwards.  Heat your room.

4

PS –  all of my resin is nice and liquid.  I sometimes have ten or so Five gallon pails sittin around for a few months.  I keep those fives in a small room about the size of a closet.  In the room I have a small electric heater set on low 24/7.  The only time it is off is summer or when I’m out of resin.

5

If your work space has no heat store your resin in another location where it will be at least 70 degrees at all times. Another method to get your resin up to a good working temp is to put the container of resin in a tub of warm water for a few hours. It would have to be pretty cold for it to become really viscous. I’ve used resin in 60 degree weather and it wasn’t noticeably thicker than at 75.

6

thank you guys for sharing.

I`m going to aim at warming up the room, then.

luckily I asked first. 

 

7

A safe way to heat your resin is using the “au bain marie” technique: putting a cup of resin in a bucket of hot water.

This way you do not risk any overheating.

Best is to cover your resin cup with some plastic wrap to avoid water intrusion.

 

Just for your reference, I never use polyester, just wanted to bring up this technique that I use with epoxy.

 

You really do not want to put resin in a microwave, especially when you also use it for food.

8

I would never heat resin of any kind in a microwave. Never.

For resin warmed by air temp, actual resin temp will reflect the average of the high and low air temps in the area where it is stored.

Effective/complete mixing is the main objective.

I was referring to the heating pad method of resin warming that Barry Snyder has mentioned here at Sways.

Barry uses a reptile heating/warming pad to keep resin at his preferred temperature, all winter.  (Search, “Snyder reptile heating pad.”)

You can purchase “thermostat controlled” reptile and “seedling” heating pads,  They can be set for a precise temperature.  (You don’t want to warm reptiles or seedlings too fast either.)

Using a thermostat controlled heating pad is cheaper than heating up an entire room.

For resin warmed by air temp, actual resin temp will reflect the average of the high and low air temps where it is stored

BTW never heat resin that has already been catalyzed.