Replies

1. 
   JayS | Feb 18, 2007 12:25am | #1

   The "fumes" from shellac are alcohol.  If brushed on you might get away with it, but when aerosolized in a  spray there is a fire/explosion hazard from electric lights and other sources such as a pilot light in your water heater.  I use an organic vapor mask and spray outdoors.  By the way, if you have mixed it from flakes the alcohol is denatured (mixed with benzene and other additives) to prevent you from drinking it.  Therefore, some of that is in the vapor as well.

   Jay

1. 
   forestgirl | Feb 18, 2007 09:05pm | #7

   Wow, I didn't realize benzene was one of the additives for Denatured Alcohol.  Out comes the respirator!  For "All":  Benzene is quite carcinogenic (leukemia).  It's one of the reasons breathing gasoline fumes isn't a great idea.

   Thanks for the info, Jay.  Off to read the MSDS.

   Edit:  So far, I've looked at the MSDS's of 7 or 8 different companies' denatured alcohol, and none of them had benzene.  It's looking like that particular additive is pretty rare.  Will continue looking.

    

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

   Edited 2/18/2007 1:11 pm by forestgirl

1. 
   BigNat | Feb 19, 2007 03:49am | #8

   The stuff I use is denatured with isobutyl alcohol.

   Edited 2/18/2007 7:50 pm ET by BigNat

2. 
   frenchy | Feb 19, 2007 05:46pm | #10

   forestgirl,

     Just read the can and it will have what the added ingrediant is. It's possible to buy alcohol without the denaturing but you'll need connections.. medical grade alcohol doesn't have the denaturing in it but the price is significant unless you can talk a buyer from a hospital into being your friend..<G> 

     you can also buy industrial grade alcohol in bulk if you plan on using 55 gallons.

1. 
   joepez | Feb 19, 2007 06:32pm | #11

   I just basically dont want to blow the house off the foundation, or handicap the kids upstaires w/the fumes.

   Thanks Joe P

1. 
   frenchy | Feb 20, 2007 01:44am | #13

   joepez,

     Alcohol isn't explosive like some solents.  Lacquer thinner for example is far more volitile.  Alcohol will quickly go out if diluted with water, other thinners will float on top of water and increase the problem of fire.   Alcohol on the other hand blends right into water and that dilution will quickly put it out..

2. 
   Biscardi | Feb 20, 2007 02:14am | #14

   Frenchy,

   I dunno. I think if you aerosolize it it probably could explode- only one way to tell I guess.

   I thought the denaturing agent is methyl alcohol.

   I thin it to a two lbs cut and wipe it on. Usually I am doing fairly small pieces (tables or smaller).

   Regards,

   Frank

3. 
   joepez | Feb 21, 2007 08:01pm | #23

   Frenchy,

   Thanks for the answer. Ok, how much should I thin down the flakes? I just want to put a quick finish on some shop drawers.

   Thanks for all your and others help here.

   Joe P

4. 
   frenchy | Feb 23, 2007 08:47pm | #26

   joepez,

     I generally use the premixed stuff, but it amounts to a one pound of flakes to one gallon of denatured alcohol.  or 1/4 # of flakes to a quart of denatured alcohol.. or some fraction of that.. You simply cannot get it too watered down.. the more alcohol the better if you are a sloppy painter like I am..  If you're neat and tidy you might be able to use a little higher concentrate but at a risk of dry brushing.. dry brushing is absolutely the worst mistake you can make..  Flood it on and let it level itself.. heck it's probably a whole lot smarter than most people. so let it do it's thing.. Don't fight it!

3. 
   JayS | Feb 19, 2007 11:10pm | #12

   Sorry if I misled you about the benzene, but I was told that by an organic chemist I know.  Whatever they put in, is put in with the intention of making it toxic to avoid human consumption.  The history of this would be interesting to research.  I wonder if it relates to liquor licensing.

   Jay

1. 
   HowardAcheson | Feb 20, 2007 03:56am | #15

   >> I wonder if it relates to liquor licensing.Of course. And to state and federal liquor taxes too.Howie.........

1. 
   BigNat | Feb 20, 2007 05:09am | #16

   Here's an article pertaining to the production of ethanol;http://en.wikipedia.org/wiki/EthanolOf particular relevance is the section on purification.
   You can also search "Denatured alcohol" for the techniques and reasons for denaturing.

2. 
   forestgirl | Feb 20, 2007 07:59pm | #18

   "You can also search "Denatured alcohol" for the techniques ... for denaturing."  This is true, but in an admittedly small sample, I found that the ones that mentioned benzene as a denaturing additive were quite old. forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

2. 
   tms | Feb 20, 2007 07:10am | #17

   " Whatever they put in, is put in with the intention of making it toxic to avoid human consumption. "Actually, the reason that it's denatured is to avoid the creation of azotropes. Ethanol will absorb water from the air and form a stable mixture, an azotrope. The solvent strength of the ethanol is thus compromised and it will turn shellac a milky color. The various combinations of solvent added (like benzene) prevents the absorbtion of water without effecting its value as a solvent. Fortunately, other compounds have been found to replace benzene.Tom

1. 
   JayS | Feb 20, 2007 08:29pm | #19

   Makes sense.  Thanks. The original question was about safety indoors, and whether methanol or other compounds, I wouldn't want to be breathing it in a confined space.  If not carcinogenic, methanol is at least toxic to the optic nerves.

   Jay

2. 
   Rich14 | Feb 21, 2007 01:30am | #20

   tms, I was always taught that the benzene in laboratory, reagent-grade "absolute" ethanol was for the purpose of removing the last traces of water from the next highest grade, 95% ethanol - from which it was derived. (95% being the amount of ethanol vs 5% water which is an inevitable by-product of the alcohol formation.) I was never sure how the addition of benzene could remove water from the mixture. How does it prevent ethanol from absorbing atmospheric water? Rich

3. 
   tms | Feb 21, 2007 01:43am | #21

   Hey Rich,You're correct, the benzene is added to the distillate after the first reflux distillation. The benzene, ethanol, and water form an azeotrope that can be further distilled to leave more water behind. It'still not 100% dry, but the resulting azeotrope of ethanol and benzene, is less hygroscopic than ethanol alone.Tom

4. 
   Rich14 | Feb 21, 2007 03:24am | #22

   Thanks.

5. 
   AlanWS | Feb 21, 2007 08:08pm | #24

   That's almost right. An azeotrope is a constant-boiling mixture. Ethanol and water form an azeotrope at 95% ethanol/5% water that boils a bit lower than pure ethanol, so if you try to get pure alcohol by distillation from a water ethanol mixture that begins with more than 5" water, 95% is as pure as your ethanol will get.If you then add a little benzene, you can form a ternary azeotrope, meaning that the first thing you distill out is a constant boiling mixture of ethanol, benzene, and water. What you have left behind can then be distilled to be almost completely water-free (anhydrous) ethanol. Several decades ago, this was the major method for manufacture of anhydrous ethanol, and was the reason it was slightly contaminated with benzene. That's not how it's done today.

6. 
   Rich14 | Feb 21, 2007 10:18pm | #25

   Alan,

   Thanks for that explanation.

   OK, how is it done today?

   Rich

2. 
   frenchy | Feb 18, 2007 03:35am | #2

   joepez,

    If I brush it on it's not a problem, I'm a really lousy pianter, I mean world class mess!

    so what I do is vastly overthin it and just flood it on.. that way no runs or drips etc. show up. 

     When I spray if I use my regular gun the fumes are pretty intense but they disapate quickly.. If I use my HVLP gun and set the pressure to the low side the fumes would almost be something I could handle, they disapate so quickly that I don't think there is much vapor issue.. alcohol isn't like lacquer, Only 2$% of it is nasty stuff (just enough so kids can't drink it for a cheap high drunk)  the rest is the same stuff you smell at your local bar..

     As for explosive I honestly believe that alcohol when it disapates absorbs a lot of moisture right from the air once a certain amount of moisture is picked up it's impossible to get alcohol to ignite..

    Test it yourself. put a tiny amount in a small pan and light a match it will burn with an almost invisable flame.. now add just some  water to that alcohol and try to get it to burn!

    

1. 
   highfigh | Feb 18, 2007 07:30pm | #4

   Alcohol is highly flammable and it's definitely not "impossible" to have a problem. It's not as explosive but it's very easy to have a problem and not know it because the flames are hard to see in the light unless there's a lot of fuel being added to the fire. The alcohol mixes with water and dilutes, so it's not going to burn but there's not that much water in the air that it "can't" ignite unless you're talking about a very large space. In a basement, it would be pretty easy to have a fire if the shellac is being used for a long time or being sprayed. I would never use shellac or any other flammable solvent inside my house without venting the fumes to the outside. Also, intense fumes from alcohol are toxic.
   "I cut this piece four times and it's still too short."

3. 
   johndl | Feb 18, 2007 05:58pm | #3

   Use Everclear for your thinner for shellac and enjoy the fumes.

1. 
   highfigh | Feb 18, 2007 07:31pm | #5

   "Use Everclear for your thinner for shellac and enjoy the fumes"I think I'll finish this with an eye-opener.
   "I cut this piece four times and it's still too short."

   Edited 2/18/2007 11:31 am by highfigh

2. 
   joepez | Feb 18, 2007 07:42pm | #6

   Yea, but I prefer my libation in a glass.

   HaHaha.

   Joe P

4. 
   Patto | Feb 19, 2007 07:25am | #9

   You could try thining it with scotch or brandy to improve the smell ;)