Exploding Rosin Box

After reading an excerpt from “Art Hazard News,” 1989, by Angela Babin, M.S. entitled “Rosin Hazards” I was concerned that, while the concept of an “exploding Aquatint box” due to rosin dust ignited by an electric spark sounded plausible, Ms. Babin’s assertion did not have an attribution. To quote the article: “In one incident, rosin dust contained in an Aquatint box exploded from a spark generated by the electric motor used to stir up the rosin dust.”
If this actually happened I would like to know where it took place, when it happened, and what it would take to cause this to happen again. How intense a spark, for what duration, and exactly what concentration of rosin dust contained in what volume would cause this to happen? Also, how could one construct a rosin (Aquatint) box to keep this from happening? Would it be enough to build the box of wood (no metal internal to the box) and only have the electric motor completely outside the box?

A tendency to explode is a nearly universal characteristic of many dusts. Grain and flour dust explosions happen fairly frequently - one cite I saw says there were 16 such explosions in the US in 1997. Silo explosions tend to be huge and fatal. I’m guessing a rosin box explosion is more like “BANG!” and popping the lid off.

I just took a quick look at print-making hazards, and dust seems like one of the lesser dangers, compared to the acids and solvents used.

Considering that the point of the box is to contain a “rosin dust storm” I don’t think there’s any avoiding the hazard, but since the headlines are not filled with accounts of artists being blown to bits, it’s probably a fairly unlikely hazard.

The motor may or may not have been the source of the spark. If it was an AC induction motor (as is common in for example portable fans), then there’s no electrical contacts being made/broken that could cause a spark. If OTOH it’s a DC motor, then it may have a commutator that features sparks as a byproduct of its normal operation.

The most likely source of ignition is static electricity. The static charge builds up from the repeated impacts of particles against each other and against chamber surfaces. I have a sandblaster at home that’s poorly grounded; the aluminum oxide blasting media thankfully doesn’t combust, but on some occasions I’ve gotten zapped so bad with static sparks that it made my arm twitch; felt like someone snapping a rubber band on my skin.

Bottom line is, static charge will build up in there as a normal part of operation. Ground straps (e.g. metal screen mesh on inside surface(s) of the box with a wire going to the ground pin on the electrical outlet) might help dissipate the charge before it gets big enough to cause troublesome sparks.

Thanks for the replies, but please don’t assume that “because it has the potential to explode” that it, in fact, has exploded. I have not found an actual first-hand account of a Rosin Box exploding. Yet I have found many anecdotal accounts, most traced back to Ms. Babin and her assertions, none of which can be verified. Since logic tells us that rosin dust has the potential of causing an explosion, and electric motors can throw off sparks or generate a large static charge (possibly enough to ignite a concentration of rosin dust if it meets certain criteria), then if such an explosion had happened it seems to me it would have had some “press.”

One more small point: Please don’t believe all the scary info in “print-making hazards” or any other “expert source,” since Printmakers tend to be almost as careful as Chemists or others working with hazardous substances and are always looking for less dangerous, but as effective, methods of making art.

If an enclosed wooden box, approximately 27 cubic feet internal volume, only contains rosin dust and a puff of air I do not see how it can explode. Just saying…

No? I can.

I don’t know anything about the rosin dust you are talking about, but any kind of combustible dust can create an explosion. You need three things. First, you need some kind of fuel. Second, you need air. Third, you need a source of ignition. Put all these together, and KABOOM!

This is why dust is such a hazard. Whenever you have any type of combustible dust, you already have your fuel and air mixed together. All you need is a source of ignition, and you’ve got your earth-shattering kaboom. And the dust does not have to be a material that you would normally think of as explosive. Heck, flour and coffee creamer are both quite combustible.

Want to prove it for yourself? Take a baggie of coffee creamer or flour, open it up, and quickly push down on the baggie so that all of the powder goes flying out of the bag, and have it blow over a lit candle. Actually, don’t do that, because you can burn yourself quite badly and burn your house down while you are at it. But trust me, it makes a rather spectacular little explosion.

If your rosin dust as as flammable as coffee creamer, then it will easily do the same thing.

A 27 cubic feet volume of it sounds to me like it would be big enough to possibly cause a fatal injury.

I found a video of someone throwing a bag of flour into a campfire, in case you want to compare that. This is a bit more “fuel” than your rosin box will probably have in it though, but it does illustrate the point I think.
http://www.youtube.com/watch?v=ve0798jC0RE

Again, thanks for the information but I did specify that there was no “internal source of ignition.” I don’t have a problem with the mechanics of “dust causing explosions,” but my concern is that an assumption has been made that ‘If it can happen then it has happened.’ I’m looking for an instance where it actually has happened, not for whether or not it can or for third party ‘knowledge’ of somebody knowing someone it happened to somewhere at some time in the past. I will, unless I can be proven otherwise, treat the ‘exploding Printmaker’s rosin box’ as Urban Legend.
Again, thanks for the information and for taking the time to give me your views.

Good point. This thread is rather speculative, but rosin burns very well. Any spark from anywhere in a cloud of rosin dust should set it off.

Similar but different is the situation that happens with ether kept in a refrigerator.Ether is volatile. Any imperfection in the seal and when the refrigerator compressor motor kicks on, POOOF!

They actually make “explosion proof refrigerators.”

I have read this account of “exploding aquatint boxes” on other sites relating to printmaking. I feel certain that this is more a health and safety “Chinese whisper” than fact. Has anyone actually experienced this phenomenon? I have used a gas poker to fuse rosin dust onto etching plates for several decades now and have yet to meet with such a disaster.

Just because you are risk adverse that does not mean that all other printmakers are equally risk adverse. Also the fact that a printmaker is aware of a particular hazard does not make it any less scary or real, it just means you have taken steps to mitigate the hazard.
Finally under the right conditions of humidity I could see a static charge building up in the dust in the box and going boom. Very similar to a static discharge causing a fire at a gas pump. It is very rare but under the correct conditions a person who gets back into their and then back out while dispensing fuel can start a fire when they grab the pump handle. Here is one such video http://www.youtube.com/watch?v=ufcQd1qoDAs&feature=youtube_gdata_player
Now I have been putting gas into cars for over 40 years and this has never happened to me. That does not mean that the risk does not exist it means I have never fulfilled all the conditions necessary to make it happen (low humidity + static + correct concentration of fuel vapors)