garyj
Furthermore, I have an issue only tangentially related to painting. I find the fumes from solvent-based plastic welders and glues to be intolerable. I have tried Weldene which smells much better and won't melt my brain, but it doesn't seem to work as well as Tenax and friends. I read a sheet from 3M about working with dichloromethane, and they suggest that the only safe way to work with it is to use an external air supply. Obviously this is overkill for the tiny amounts used by the hobbyist, but it underlines the fact that an R95 respirator is insufficient. So, will a spray booth be able to evacuate those fumes so that they don't bother me? I realize that some exposure is inevitable, but I'd like to get that low enough so that I don't get a solvent hangover.
A couple points, if I may:
1. An R95 respirator is indeed going to be insufficient because it's designed to filter particulates, not the organic vapors associated with using glues. But you bring up an interesting point. Even organic vapor cartridges are less efficient with methylene chloride because the molecule is not very polar, and as a result, it doesn't adsorb well onto activated charcoal.
2. You may find using a spray booth to be self-defeating. Working inside a booth pulling gobs of air may cause much faster evaporation of your glues, so that the glue either evaporates before you get it on the part, or it dries/evaporates too quickly leaving you with an inadequately glued part. This is solved, in part, by using higher volumes of glue to do what you did before with smaller quantities. Ultimately, you're throwing money out the window.
3. If you're concerned about solvent exposures/odors, you might want to consider changing glues. Try substituting Testor's Liquid Cement for the Tenax you're currently using. Testor's uses methyl ethyl ketone (MEK) as their primary ingredient as opposed to methylene chloride (dichloromethane) for the Tenax brand. MEK is much less toxic than dichloromethane, and it evaporates much slower, so glue odors don't become bothersome as quickly. Testor's also has the added benefit of setting a little slower, allowing a little longer to make any final adjustments on glued parts. When dry, the bond is as strong as that of Tenax. I use both Testor's and Tamiya glues. Great stuff. (As an aside, MC has been implicated, and is gaining momentum, as a human carcinogen. You can access the National Toxicology Program website for more information.)
4. Finally, a couple common sense alternatives: Instead of a spray booth, put a small room fan at your back or to the side of your work area. It will direct vapors away from your breathing zone, dilute the vapor concentrations as it redirects airflow, and won't prematurely dry out your glue or your parts. Next, use a small paint brush, or one of the popular applicators available for gluing parts instead of the applicators that come with the product. Keep the glue bottle covered when you're not using it, and place the glue bottle further away from your face during use--either move the bottle or your face away from the open bottle.
Hope this helps you some.
Gip
P.S. As far as booths go, it's going to boil down to what you like and can afford, as well as what you purpose to do with it. For us hobbyists, a downdraft booth is just as good as a back-drafted booth. There really aren't any issues asscociated with overspray or capture that I'm aware of. Downdraft booths use gravity to help capture organics and particulates, hence the lower airflow rates. In addition, those lower airflow rates allow an activated charcoal filter to be placed below the particulate filter for the purpose of catching the organic vapors. So if you can't--or don't want to--exhaust your airflow outdoors, the downdraft may be the way to go. If you're spraying really large kits, or you like to go crazy using rattlecans to paint with, or you have a high volume/high pressure paint gun (or if you want to spend less money), then the back-drafted may be more to your liking, because it uses much higher airflow rates to capture particulates and vapors. But it will require you to use exhaust ducting to get the contaminants outdoors.
Oh, and sorry for the longish post.
Gip