Prop Making Safety Guide

Sean Bradley has already written a similar guide that is stickied in multiple places, but he also encouraged other people to fill in the blanks and I think I can fill a gap here with a different structure and a more material-specific approach.

I'm trying to condense all the information you need into one document, but to keep it simple enough for everybody to understand and colourful enough so that noobs don't feel textwalled, run away and get themselves killed.

Click the previews to get to the document. Yes, it's more than four pages. Download the PDF from Google Docs for better quality pictures.

one thing about smoothon products is that if you get them on your skin they will get in your pores and never come out. Learned that from experience. always wear gloves

Charlieiscool12 said:

one thing about smoothon products is that if you get them on your skin they will get in your pores and never come out. Learned that from experience. always wear gloves

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That's why this neat little glove symbol is all over the tutorial.

hmm, that's why I'm so retarded... Need to wear gas mask more, and definitely pick up a more modern (aka easier to find filters for) gas mask, or half-mask.

Thanks for the document! Handy to have this information all in one place now.

Wow, great document! Glad to see things are finally turning as far as safety and working with Smooth-On products.

I just had an idea for the forums in general: Maybe it should be required that people who post tutorials also post the general safety gear required. If we had a general set of standard images(dust mask, organic/inorganic respirators, gloves, etc. just the major things) that you could include in your posts and maybe they link back to this document. This would reinforce the notion of general protection and it would be implicit that the person doing the tutorial also understands the safety requirements and is not passing bad habits on to other people.

Zat German said:

Wow, great document! Glad to see things are finally turning as
far as safety and working with Smooth-On products.

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Thanks!

Ironically, Sean's safety guide does say to wear a respirator when using those products - and it's been there for quite a while. I don't know when SmoothCast was "discovered" on the 405th, but I know that the source that mislead me once is several years younger. The problem really isn't that the information isn't there, it's that people don't care.

I just had an idea for the forums in general: Maybe it should be required that people who post tutorials also post the general safety gear required. If we had a general set of standard images(dust mask, organic/inorganic respirators, gloves, etc. just the major things) that you could include in your posts and maybe they link back to this document. This would reinforce the notion of general protection and it would be implicit that the person doing the tutorial also understands the safety requirements and is not passing bad habits on to other people.

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The pictograms I used are in the public domain, you can get them from the respective Wikipedia articles.

The blue ones are mandatory signs, the yellow ones are danger signals and the red ones are prohibition symbols. All of these are standardised in my country but should be recognisable all over the world. The orange ones are chemical hazard symbols, these are standardised in all of Europe, but are deprecated and should or will be replaced by the new GHS symbols. You will see those in the US as well.

I wouldn't use product shots, they might mislead people.

It looks like you mentioned everything, I especially liked this part:

6.1.1 Ill just wrap a scarf/bandana/shirt/cat/surgeon's mask/piece of cloth/this guide around my head and that will protect me
No it wont. Think about it- everybody would just use a few old rags if that helped!

I liked how you knew dumb people would try to use a cat, or the safety guide as a replacement for a respirator.

Trust me some people are that dumb.



Also you could add a part about how it is not meant for airsoft/paintball use, without actual airsoft/paintball aproved gear.

Thank you Ventrue

This is very well done. I'd go as far as saying THIS should be the very first thing a person Should READ before starting a build. It will give them some idea what they will need and/or what type build they can safely go within their Space, skill level, and budget.

If you can't afford the safety gear then you can't afford to work with that medium.

The life you save just might be you're own.

Thanks again Ventrue, I'm going to add this one to my links page.

I am definately saving this to my links to give to noobs. They might light themselves on fire if they are misinformed.

Toacrabman said:

Also you could add a part about how it is not meant for airsoft/paintball use, without actual airsoft/paintball aproved gear.

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I'll keep the idea in mind, but I think that would go beyond the scope of the guide. It's about building the stuff, not about what you do with it afterwards.

thorn696 said:

Thank you Ventrue

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Glad you like it

Toacrabman said:

They might light themselves on fire if they are misinformed.

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Funny you mentioned that @_@ It may be worth mentioning that the curing of some of the compounds can yield an enormous amount of heat. This may not be relevant to the focus of the guide, and the danger it poses might be minimal. I had Bondo'd a model and due to making it a "quick" batch, and it being a hot day (around 87F) it threw off so much heat it began melting the plastic tray I had set it on. Granted I mixed it up too hot, and the higher-than-average heat isn't likely to be encountered by most, but it may warrant a small footnote at the end to warn of the cure heat.

It may also be worth mentioning the dangers of contact lenses and chemicals. The vapors can absorb into the contact lenses as it's a permeable plastic, and now it's in constant contact with your most vulnerable of organs, and the danger is present for both disposable lens, and long term use lenses. My Optician is a hobbier and told me about it, and it seems like a valid concern. He told me that it would be best to wear glasses instead of contact lenses, or a full face mask when working with any type of chemical/toxic compound, though he cautioned that with a full mask you might remove it, then go out to check on your work while it's still a danger. The long term use lenses are even more of a threat, because once they absorb the fumes you're putting it directly onto your eyes daily until it is time for a new pair, which can be a month or longer depending on the type.

Just my two cents, but other than that the guide was very comprehensive and it'll prove to be a good safety primer for newcomers like myself to help boost safety knowledge and awareness.

Jake D said:

but it may warrant a small footnote at the end to warn of the cure heat.

It may also be worth mentioning the dangers of contact lenses and chemicals.

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I'll look into that.

ventrue said:

Evidence suggests that urethane products can continue to emit isocyanates even long after they are cured, sometimes for many months.

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This is from page 13. Do you have any citations that expand on this? I cannot unfortunately read the German one, despite my account name. Isocyanates have been a real thorn in my side as far as using Smooth-On products and whether I should worry about long term exposure(the primary use at the moment would be for filling voids in a helmet with Foam-It 10) post-cure.

Tonight I purchased access to "Flexible Polyurethane Foam. I. FTIR Analysis of Residual Isocyanate" which is an article from Journal of Applied Science, Volume 34, Issue 1, July 1987, Pages: 395–407, K. C. Cole, P. Van Gheluwe, M. J. Hébrard and J. Leroux. This article seems to be cited in a lot of isocyanate research on health effects.

Basically, they used Fourier transform infrared techniques to measure the amount unreacted isocyanate present when cutting them open after they had been left in both dry and humid environments.

The long and short of it was that unreacted isocyanates were present in higher concentrations for a longer time in a dry environment than in a humid environment. Temperature and humidity at foam creation affected the amounts detected, with higher humidities and temperatures leading to less isocyanates being present. The article concludes with:

After a period of approximately 1 week, the residual isocyanate concentration becomes virtually stable. Only severe hydrolytic conditions accelerate the depletion of the remaining isocyanate groups.

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which seems pretty hopeful to me.

Now, there are some things that need to be said about the conclusion I am drawing from this. One, they are talking about flexible polyurethane foam and Foam-It 10 is a rigid foam which is ultimately a difference of open cell vs. closed cell foam. I do not know if this affects the speed of outgassing but it seems like closed cell foam would outgas slower. Two, I have no idea how the test foam actually compares to Smooth-On's products, but I am trusting that Smooth-On has done the research and it is as good or better as far as toxic substance presence after cure. Three, there would still be a danger of unreacted isocyanates being released when sanding or cutting into the foam post-cure, especially within that first week to 10 days(this is longest period the study covered).

So, those are some of my thoughts on that particular subject. I hope this was an appropriate thread to expand the discussion on isocyanates. I just want to find the best, safest products to use for myself as well as everyone else. The last thing I would want to see is someone developing asthma or deteriorated lung function due to improper use of products in a hobby.

Zat German said:

This is from page 13. Do you have any citations that expand on this? I cannot unfortunately read the German one, despite my account name.

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Sources 3.6 and 2.3 are the relevant ones here. The latter is German and seems to be scanned from a paper version, so unfortunately Google Translate doesn't work. It's talking about several experiments where urethane insulation foam raised the isocyanate and amine concentration in rooms over a time of several months and where particle boards emitted isocyanates for ten days. The document looks very well researched, so I would assume that if the problem just vanished after a week, it would say so.

I am trusting that Smooth-On has done the research and it is as good or better as far as toxic substance presence after cure.

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I believe that Smooth-On makes good products and I believe that they tell you as much about safety as they are legally required to do. I wouldn't go as far as to say that their products are less toxic than the ones of other manufacturers. In that context, you should read source 3.6. Open the SmoothCast 320 MSDS while reading the chapter "SALESPEOPLE TELL ME THAT THEIR PRODUCT IS 'DIFFERENT.'"

Even if a resin was "less toxic" once cured, that would rely on you measuring and mixing the two parts perfectly - which is close to impossible, especially at home. There's always a good chance that at least in some of your material there is a surplus of one part, which will then find no partner to react with and just keep sitting there forever, doing whatever it likes.

ventrue said:

Sources 3.6 and 2.3 are the relevant ones here. The latter is German and seems to be scanned from a paper version, so unfortunately Google Translate doesn't work. It's talking about several experiments where urethane insulation foam raised the isocyanate and amine concentration in rooms over a time of several months and where particle boards emitted isocyanates for ten days. The document looks very well researched, so I would assume that if the problem just vanished after a week, it would say so.

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Hmm. I am going to OCR that German paper with Adobe Professional at work today and try to run it through Google Translate to get some more information out of it.

Open the SmoothCast 320 MSDS while reading the chapter "SALESPEOPLE TELL ME THAT THEIR PRODUCT IS 'DIFFERENT.'"

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Yeah, this is still an excellent point and I am glad you make it in the guide. At the end of the day though, it really comes down to trust and good safety gear. I found a urethane-based foam product for the model rocket industry that literally has no safety information whatsoever. Nothing on handling or working with it. Not on their website or any of the pre-sale product information I could find. That seems plain irresponsible.

Even if a resin was "less toxic" once cured, that would rely on you measuring and mixing the two parts perfectly - which is close to impossible, especially at home. There's always a good chance that at least in some of your material there is a surplus of one part, which will then find no partner to react with and just keep sitting there forever, doing whatever it likes.

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Yep. I think this is one of the reasons why Smooth-On's documents stress mixing and mixing technique. Though you could always attempt to undermix the Part A using a graduated cylinder or something. Then at least you have unreacted Part B, however Smooth-On does not identify what chemical(s) Part B is. You could also add a small amount of water to it, to help disperse the extra isocyanates but that is going to change the composition in the case of foams and may cause the chemical reaction to fail if you use too much.

Zat German said:

Yep. I think this is one of the reasons why Smooth-On's documents stress mixing and mixing technique. Though you could always attempt to undermix the Part A using a graduated cylinder or something. Then at least you have unreacted Part B, however Smooth-On does not identify what chemical(s) Part B is. You could also add a small amount of water to it, to help disperse the extra isocyanates but that is going to change the composition in the case of foams and may cause the chemical reaction to fail if you use too much.

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I think the reason they stress mixing so much is rather that they want their product to work, so that you like it - and buy it again

Sure, you can use all kinds of tools to help you measure and mix, but they all require some experience to use correctly and you're even short on time while doing it. It may sound stupid, but the average person does not know how to read a graduated cylinder correctly and precisely hitting your goal (with either a cylinder or scales) is also an art by itself.

I also wouldn't add anything to those chemicals, especially not in this case, because isocyanates react with water. This will at best mess up your resin batch.

ventrue said:

It may sound stupid, but the average person does not know how to read a graduated cylinder correctly

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Science classes must have really gone downhill these days. Then again, they let us play with raw mercury in junior high...

I've made some changes, corrections and additions and uploaded revision 2.1. Enjoy

Jake D said:

It may also be worth mentioning the dangers of contact lenses and chemicals.

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In that contect: I've looked into the contact lens issue and added a section about it, but I'm afraid I came to a different conclusion than you.

Can you please look into issues regarding EVA foam? It's still relatively new but getting more and more popular, and I'm not sure what concerns we should have about working with it.

In particular, are there any dangers when using a dremel rotary tool on it, or a hot knife / soldering iron; and if there's anything to worry about hot glue guns. Haven't really been able to find anything reliable on these issues, but it seems you know where to look a lot better than I do...

What are the best masks and filters?