How toxic is resin?

[No_6]

So I've been experimenting with Smooth-On Crystal Clear 202, and I really like it. I used a proper respirator and did it all in my bathroom with the window open. After I finished casting, I kept the door closed and window open for a couple of hours to ventilate. I only mixed a small amount (about 2-4oz), but there was no perceptible odor. Was the 2 hours of venting enough? Or does resin keep releasing toxic (& odorless) vapors for much longer?

BTW, the instructions indicate that CC 202 has a pot time of 9 minutes and a mold time of 90.

[Johnnycrash]

I cast with no respirator, no venting. The stuff you get like Smooth-On and such is LOW in the toxicity area. They are designed to be used at home. The resin does off gas for about a week. But what it gives off, is nothing to worry about. This goes for polyurethane resins only. Polyester based stuff is nasty nasty nasty. Nasty to work with, nasty to smell, and all round ain't no good for you.

Now, with that said... Don't drink the stuff, or gnaw on it like you do a pen.

The most horrible of horrible of deaths would be to have a bad guy drink equal parts A & B and then do jumping jacks. It would burn due to the exothermic nature, it would also foam badly when mixed with the stomach juices...

[Umi_Ryuzuki]

The fact that polyurethane resin is mostly oderless makes it deceptive in
regards to the fumes it gives off.

I learned years ago, that if I did casting work in the garage and did not
ventilate, I would get a huge headache at the base of my scull and back of the head.
I now vent the casting pot through a hose that dumps directly outside through
a pipe I ran through the garage wall. And work with as much ventilation as possible.

[Joseph Osborn]

Crystal Clear is nastier than the regular Smooth-On stuff, so you were wise to take the precautions. Matter of fact, their website has this big warning:
"CAUTION: NOT FOR HOME USE. THIS PRODUCT IS FOR INDUSTRIAL USE ONLY." Once the resin has hardened it's normally safe to handle as long as you take the normal precautions about sanding and making dust. If the mix was improper and the casting is oozing, then I would not touch it with bare hands.

Whenever I mix & pour Crystal Clear I wear my respirator and long sleeves in addition to the nitrile gloves I normally wear. The thing about isocyanate sensitization is that you can't predict when it might affect you, so the common sense thing to do is follow the manufacturer's safety recommendations.

[Stu Pidasso]

I've been seriously casting for 4+ years now, and look at me: I'm fine!!!!

[No_6]

I've been seriously casting for 4+ years now, and look at me: I'm fine!!!!

That's reassuring!

Apart from all the warnings all over the directions (there are SO many warnings that it is kind of hard to actually find the directions--I wound up looking it up online), I've found that the Crystal Clear 202 is really easy to work with (worries about poisoning myself to death aside). The short pot time means that I don't have to wait forever if I need to fill pinholes and such.

I've been using the Crystal Clear to fill windows, and it really does look great...

[Chas]

the dangerous compound in polyurethane resin is called isocyanate. it is colorless odorless and extremely hazardous. it can be absorbed by breathing it in and also through contact with the skin.
It will not kill you and the danger is not an acute one. it is a cumulative effect. When it is absorbed it gets into your blood and stays their - it NEVER goes away. continued exposure increases the amount in your system. it has no ill effect until it reaches a critical mass in your system ( different for everyone. When you notice its effects its too late - nothing can be done. The effects usually manifest as symptoms similar to pneumonia I believe. This is known as 'sensitivity' and when it manifests it results in an intolerance to polyurethane plastics. You cannot be in their vicinity without manifesting symptoms to which their is no remedy. There is a lot of polyurethane & polyurethane blends in our lives. Sensitivity makes life extremely difficult.
the isocyanate is in the catalyst not the resin itself. When the polyurethane has cured the isocyanate has evaporated and the parts no longer pose a threat.
While the part is curing the isocyanate is evaporating into the air, so it should be vented out of your living space.

Short end of the stick Take precautions! it is not only dangerous for those using it, but if its used in your house its dangerous for all those living in the house. this is why you should cure it in sealed area that is vented outside until it has fully cured.

If you are concerned - and you should be- you should try to acquire a copy of the MSDS sheets for the resins you are using. I would suggest contacting the dealer or manufacturer of the resin and inquiring about getting a copy so that you know exactly what you are dealing with and what the potential heath effects are for yourselves and your families.

One last thing. Masks, the type used to prevent against the spread of infectious deceases, - the white ones that slip over your nose and mouth, are not sufficient protection. you need a respirator with charcoal filters 3M manufacturers some that are standard issue in the rapid prototype industry - which is an industry in which I use to work and where I learned this stuff.

[No_6]

the dangerous compound in polyurethane resin is called isocyanate. it is colorless odorless and extremely hazardous. it can be absorbed by breathing it in and also through contact with the skin.
It will not kill you and the danger is not an acute one. it is a cumulative effect. When it is absorbed it gets into your blood and stays their - it NEVER goes away. continued exposure increases the amount in your system. it has no ill effect until it reaches a critical mass in your system ( different for everyone. When you notice its effects its too late - nothing can be done. The effects usually manifest as symptoms similar to pneumonia I believe. This is known as 'sensitivity' and when it manifests it results in an intolerance to polyurethane plastics. You cannot be in their vicinity without manifesting symptoms to which their is no remedy. There is a lot of polyurethane & polyurethane blends in our lives. Sensitivity makes life extremely difficult.
the isocyanate is in the catalyst not the resin itself. When the polyurethane has cured the isocyanate has evaporated and the parts no longer pose a threat.
While the part is curing the isocyanate is evaporating into the air, so it should be vented out of your living space.

Short end of the stick Take precautions! it is not only dangerous for those using it, but if its used in your house its dangerous for all those living in the house. this is why you should cure it in sealed area that is vented outside until it has fully cured.

If you are concerned - and you should be- you should try to acquire a copy of the MSDS sheets for the resins you are using. I would suggest contacting the dealer or manufacturer of the resin and inquiring about getting a copy so that you know exactly what you are dealing with and what the potential heath effects are for yourselves and your families.

One last thing. Masks, the type used to prevent against the spread of infectious deceases, - the white ones that slip over your nose and mouth, are not sufficient protection. you need a respirator with charcoal filters 3M manufacturers some that are standard issue in the rapid prototype industry - which is an industry in which I use to work and where I learned this stuff.

Thanks Chas! That's good to know. I'll just have to do my casting somewhere other than my bathroom. Or add an additional fan.

[Chas]

Due to some inaccuracies in my last post (its been a while so I'd forgotten some things and remembered others incorrectly. Here is a link to a fact sheet on isocyanates. Its 23 years old, but its accurate and still very useful.

http://www.cdph.ca.gov/programs/hesis/Documents/iso.pdf

If you use polyurethane resins please read it.
and here is what the OSHA has to say about Isocyanates.

Isocyanates are compounds containing the isocyanate group (-NCO). They react with compounds containing alcohol (hydroxyl) groups to produce polyurethane polymers, which are components of polyurethane foams, thermoplastic elastomers, spandex fibers, and polyurethane paints. Isocyanates are the raw materials that make up all polyurethane products. Jobs that may involve exposure to isocyanates include painting, foam-blowing, and the manufacture of many Polyurethane products, such as chemicals, polyurethane foam, insulation materials, surface coatings, car seats, furniture, foam mattresses, under-carpet padding, packaging materials, shoes, laminated fabrics, polyurethane rubber, and adhesives, and during the thermal degredation of polyurethane products. Health effects of isocyanate exposure include irritation of skin and mucous membranes, chest tightness, and difficult breathing. Isocyanates include compounds classified as potential human carcinogens and known to cause cancer in animals. The main effects of hazardous exposures are occupational asthma and other lung problems, as well as irritation of the eyes, nose, throat, and skin.

[No_6]

Lord. Now I'm convinced that I've poisoned myself for life. I didn't wear gloves & got it on my hands. I wonder how long I've got until my hands fall off.

[Johnnycrash]

Chas is a little off base posting that info. If you look at it closely, the "deadly" effects are for breathing in the fumes. That really only happens when the isocyanate is in vapour form. If you look at the list of products, all of those need the isocyanate to be "aerated", as in airborn mist. Or when the product is subject to thermal degradation (fancy word for burning).

In the resins it is held in solution. So, unless you are burning it, using it to spritz the cat, or a beer chaser... It is perfectly safe to use.

[No_6]

Chas is a little off base posting that info. If you look at it closely, the "deadly" effects are for breathing in the fumes. That really only happens when the isocyanate is in vapour form. If you look at the list of products, all of those need the isocyanate to be "aerated", as in airborn mist. Or when the product is subject to thermal degradation (fancy word for burning).

In the resins it is held in solution. So, unless you are burning it, using it to spritz the cat, or a beer chaser... It is perfectly safe to use.

Thanks for making me feel better.

[Chas]

Isocyanates can affect you when they evaporate into the air you breathe or when they form a mist or a dust in the air, or if they come into contact with your skin.

Evaporation happens without burning, no? When part a & part b are mixed together is there not heat given off?

Regardless if you know better than the health professionals more power to you.
No_6 was asking about the health risks and toxicity of resins and I gave just that to the best of my knowledge. If you want to provide council to disregard that information you are entitled to do so.
I used polyurethane resins 5-6 days a week 10-12 hours a day for 2 years and always wore the proper personal protective equipment. You don't bother and think you are 'fine' that's great. I just hope you can live with yourself if someone else follows your example and advice and get's ill.

[Darthsideous]

the dangerous compound in polyurethane resin is called isocyanate. it is colorless odorless and extremely hazardous. it can be absorbed by breathing it in and also through contact with the skin.
It will not kill you and the danger is not an acute one. it is a cumulative effect. When it is absorbed it gets into your blood and stays their - it NEVER goes away. continued exposure increases the amount in your system. it has no ill effect until it reaches a critical mass in your system ( different for everyone. When you notice its effects its too late - nothing can be done. The effects usually manifest as symptoms similar to pneumonia I believe. This is known as 'sensitivity' and when it manifests it results in an intolerance to polyurethane plastics. You cannot be in their vicinity without manifesting symptoms to which their is no remedy. There is a lot of polyurethane & polyurethane blends in our lives. Sensitivity makes life extremely difficult.
the isocyanate is in the catalyst not the resin itself. When the polyurethane has cured the isocyanate has evaporated and the parts no longer pose a threat.
While the part is curing the isocyanate is evaporating into the air, so it should be vented out of your living space.

Short end of the stick Take precautions! it is not only dangerous for those using it, but if its used in your house its dangerous for all those living in the house. this is why you should cure it in sealed area that is vented outside until it has fully cured.

If you are concerned - and you should be- you should try to acquire a copy of the MSDS sheets for the resins you are using. I would suggest contacting the dealer or manufacturer of the resin and inquiring about getting a copy so that you know exactly what you are dealing with and what the potential heath effects are for yourselves and your families.

One last thing. Masks, the type used to prevent against the spread of infectious deceases, - the white ones that slip over your nose and mouth, are not sufficient protection. you need a respirator with charcoal filters 3M manufacturers some that are standard issue in the rapid prototype industry - which is an industry in which I use to work and where I learned this stuff.

Thank you for posting this Chas, it is really helpful. I have been concerned about the health hazzards of casting. Thanks for posting this question No_6

[Chas]

You're welcome Darth, but as I stated there are some inaccuracies in that post. The link in my second post has more accurate information. Please read that if you have any concerns.

[MillenniumFalsehood]

With anything it is often better to er on the side of caution. Wearing a charcoal filter mask would be preferable to dealing with health effects down the road. Thanks, Chas!

[Glorfindel]

Don't breath it or drink it. If you do....
http://www.youtube.com/watch?v=GVmeeYwEiQw

[No_6]

Thanks for all the information Chas, and I definitely plan on erring on the side of safety. Since I live in an apartment, and simply lack the ability to do larger casting projects in a manner that would give the best results AND be safe, I'll be limiting myself to casting smaller parts so that I can closely control the environment.

[shiphorns]

Majority of the Smooth On and Alumilite products are very safe, because they are made with aromatic diisocyanates (MDI or TDI) that are already partly polymerized (called prepolymers) which means they are very large molecules with extremely low vapor pressures (i.e. do not evaporate much into the air around you). A lot of the warnings on industrial products pertain to these diisocyanates in their more volatile monomer forms (not at all polymerized).

As noted, the exceptions are the UV-resistant clear products. When you see these properties on a polyurethane resin, it indicates that your diisocyanate component is Dicyclohexylmethane-4,4'-diisocyanate which requires more safety precautions for these important reasons:

1. It is not as reactive as aromatic diisocyanates, so unreacted residue stays around a lot longer (self-polymerization reaction with moisture in the air takes longer). In a dry climate, it can hang around for weeks.

2. It is irritating to the skin, eyes and lungs in much, much, much lower concentrations than the aromatic diisocyanates. Permissible air concentrations in the industry are in the 5 parts per billion range. By the time you smell H12MDI, you've reached airborne concentrations WAY above what it takes to cause health problems (if you smell it, GTFO!)

3. The potential asthma-related effects can be delayed in onset. You can feel fine just after using the product, and have potentially fatal respiratory distress several hours later unexpectedly. Like with allergies, there is no way of knowing ahead of time who is at risk of serious reactions, so this is why there are all those warnings on the products.

The comment above about diisocyanate exposure being cumulative is not accurate, it's a sensitization issue not accumulation, i.e. once you've had a bad reaction to isocyanates from exposure, you're likely to keep having that reaction with increasing severity and lower thresholds on subsequent exposures.

I would not recommend using Crystal Clear 202 in your bathroom. Use it in a garage, or someplace where a messy spill would not require a hazmat cleanup to make the space livable again. Seriously, you don't want that stuff lingering in your living area.