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Resin Stuff: Heating Isocyanate Urethane & Sweating

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I contacted aeromarine products http://www.aeromarineproducts.com/casting-resin.htm

with questions about the casting resin I've been using.  So here is the Q & A from the phone call.

 

Q) My resin lures are sweating, is my resin contaminated?

A)  NO, with the increasing warming trend across the nation in the spring, our resins have a tendency to sweat out oils.

 

Q) This sweating makes it impossible to paint and clear coat a lure, is there anything I can do to alleviate the problem?

A)  YES, if you have an oven (they suggested one that you don't use for food) bake the resin at 150F for 4 hours.  This should help with the oil sweat. 

 

Q) I've heard that heating isocyanate urethane results in chronic toxicity.  Is this true?

A) YES.  However, after curing a low heat of 150F is ok.  

As a precaution, It is suggested to not do this in your house.  If you are doing this your garage have adequate ventilation (open garage door).  It is suggested to wear a mask.

 

Q) Are the gasses released from heating flammable?  Is there a risk of combustion?

A) No  (I'm personally going to use a tray to capture oils sweating out).

 

 

Just figured I would report what I was told.

 

 

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I found that allowing the baits to cure for three to four weeks after pouring pretty much eliminated the problem. As a precaution, I would put the baits through the dishwasher after allowing them to sit for the described time frame.

This may not work for all types of resins but it worked well for me.

Edited by fatfingers

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I haven't have problems with the resins I use from Alumilite. I usually let them sit a day or two just to let them harden fully. They have taken paint well.

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I contacted aeromarine products http://www.aeromarineproducts.com/casting-resin.htm

with questions about the casting resin I've been using.  So here is the Q & A from the phone call.

 

Q) My resin lures are sweating, is my resin contaminated?

A)  NO, with the increasing warming trend across the nation in the spring, our resins have a tendency to sweat out oils.

 

Q) This sweating makes it impossible to paint and clear coat a lure, is there anything I can do to alleviate the problem?

A)  YES, if you have an oven (they suggested one that you don't use for food) bake the resin at 150F for 4 hours.  This should help with the oil sweat. 

 

Q) I've heard that heating isocyanate urethane results in chronic toxicity.  Is this true?

A) YES.  However, after curing a low heat of 150F is ok.  

As a precaution, It is suggested to not do this in your house.  If you are doing this your garage have adequate ventilation (open garage door).  It is suggested to wear a mask.

 

Q) Are the gasses released from heating flammable?  Is there a risk of combustion?

A) No  (I'm personally going to use a tray to capture oils sweating out).

 

 

Just figured I would report what I was told.

 

Good info. As mentioned by other members, the best solution to painting that I have found is to put the baits in a dishwasher. As guessed from previous posts I do not use my regular dishwasher. I got a portable unit that is smaller and dedicated to baits. 

 

I would say their response to the heating question is a half truth. For any liquid, the vapor pressure increases as temperature increases. In addition, there are few ovens that can heat your bait perfectly to 150F when you factor in radiation, convection, etc. They also suggest that a mask will help. I am assuming they mean a half mask respirator with organic filtering. The problem is an organic filter half mask will not remove enough, or any of the isocyanates. 

 

I work with many veteran industrial chemists and have described my operations to them for feedback. They have all said that the best solution when working with isocyanates is a vent hood that takes all fumes (especially when heating) permanently away from the work area. They convinced me that a mask is not enough.

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I am just guessing at a solution here but have you tried washing it down with da or maybe even Dawn dishwashing liquid just before painting?

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Thanks for the input.

The lures feel and look dry before painting.  I use the dishwasher method every time too.  The oil sweat thing is recent, as I have not had this problem before (I've been using their resins for a few years now since the price was nice).  When painting, everything goes on well until I heat set.  Even just exposure in sunlight caused oil boils to occur under the paint.

 

I'm thinking of mounting some wheels onto this lab oven, and just move it outside when I heat a batch.  

This is still assuming that the heat method will work.  If not, then I need new resin.

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I've used a regular hair dryer to heat parts to 180 deg F.  Might be easier to set up a "hot box" with a cardboard box and hair dryer blowing into it.  For that matter, It shouldn't be too hard to set up a solar hot box with a couple of sheets of aluminum foil to reflect onto the box...will take longer but it's free.  I've used the off-white aero-marine casting resin.  It softens with heat so be careful to hang your baits in such a way that they don't bend when heated.

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I've used a regular hair dryer to heat parts to 180 deg F.  Might be easier to set up a "hot box" with a cardboard box and hair dryer blowing into it.  For that matter, It shouldn't be too hard to set up a solar hot box with a couple of sheets of aluminum foil to reflect onto the box...will take longer but it's free.  I've used the off-white aero-marine casting resin.  It softens with heat so be careful to hang your baits in such a way that they don't bend when heated.

Alumilite softens with too much heat as well.

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Good info. As mentioned by other members, the best solution to painting that I have found is to put the baits in a dishwasher. As guessed from previous posts I do not use my regular dishwasher. I got a portable unit that is smaller and dedicated to baits. 

 

I would say their response to the heating question is a half truth. For any liquid, the vapor pressure increases as temperature increases. In addition, there are few ovens that can heat your bait perfectly to 150F when you factor in radiation, convection, etc. They also suggest that a mask will help. I am assuming they mean a half mask respirator with organic filtering. The problem is an organic filter half mask will not remove enough, or any of the isocyanates. 

 

I work with many veteran industrial chemists and have described my operations to them for feedback. They have all said that the best solution when working with isocyanates is a vent hood that takes all fumes (especially when heating) permanently away from the work area. They convinced me that a mask is not enough.

Are there issues associated with the clear cast resins?

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Just an update.  I heated a batch of lures at 150F in my lab oven.  Based on the 2 lures I've re-painted, I've had no issues whatsoever with sweating when heat setting my paint.

 

Now, I did have to remove the old paint (using lacquer thinner).  After letting them dry for about an hour, I placed them in the warm oven for about 3.5hrs and then turned off the power for the night (but left the lures in).

 

I haven't tried this on a recently cured lure, only on the resin batch that I had all the sweating issues with.  I had the oven next to my half open garage door and made sure not to breath when I opened the hatch to check on them.

 

At 150F, I didn't notice the resin getting soft, but noticed that they were sweating out.

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http://i270.photobucket.com/albums/jj100/amcalexa/20130328_194656_zpse755b58b.jpg

 

This is the oven I received... I'm still working on a rack system, but for now I have a couple flat irons pieces going across that I just hang the lures from.  Since the lures I just "cooked" were ones that I had already tried to paint, I left the lips in (since they were CA glued anyway).  I did not notice any weakening of the lip adhesive after baking.  I chucked one all day against the rocks the day after and didn't bust a lip, so I figured it was successful.  

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