QuickTalk 16 - Q-TIPS
- Category: Q-Talk Articles
- Published: Saturday, 30 June 1984 07:11
- Written by Jim Masal
- Hits: 1382
Since I'm getting closer to painting now, I pay more attention to that area. First, check out your local grocery store magazine rack for the Hot Rod magazines, some of which are totally devoted to painting tips. Ditzler paints are mentioned over and over. They have a urethane called Deltron, which gets good reviews - especially with respect to its ability to be spot repaired like a lacquer with excellent matching. Delstar is their acrylic enamel which is cheaper, can have a catalyst added and has the same repair qualities.
The professionals have some neat tricks with masking tape. I have been advised only to use FRESH 3M for masking stripes, shooting a coat of clear first to seal the edges so that the color coat can't bleed through, as so often happens. More expensive but worth it are the new plastic fine line tapes which form tight curves easily, foil bleeding and leave less of a transition "bump" between the stripe and the base color.
Jim Masal (457), Dallas, Texas
In Quicktalk #11, p.9, reference was made to use of 1,1,1-Trichloroethane as a cleanup solvent for Epoxy. In Quicktalk #13, p.5, it was stated that Trichloroethane is a proven carcinogen. I believe that the writer in Quicktalk #13 was confusing 1,1,1-Trichloroethane with Trichloroethylene. In BIOSCIENCE for March 1984, vol. 34:144, both substances are listed with reference to carcinogenicity. 1,1,1-Trichloroethane is listed as "Negative evidence of carcinogenicity from animal bioassay", while Trichloroethylene is listed as "Confirmed animal carcinogen>"
This is a good example of similarity of names causing undue confusion. I too have been using 1,1,1-Trichloroethane for some time in cleaning up after Epoxy use. I had not written in to Quicktalk yet because until just now I was unable to find a reference to the lack of carcinogenicity of it even though I knew that it was a noncarcinogen.
Regardless of which solvents are used, even though they are "safe", it is always best to have adequate ventilation, and use a respirator if any doubt exists.
George J. Socha (2480)
This hotwire counterbalance idea is effective, simple and cheap. Hook a bungee cord to a convenient overhead beam in your garage and hang the massive hotwire saw from it. With my hotwire saw hanging in this way, it floats just a few inches above my workbench. I have never felt any weight from that monster while guiding it lightly over the templates and through the foam.
While on the subject of hotwire cutters - my rig is similar to the one described in Chapter 3 of the plans except it uses house current. The only difference is you will need a longer voltage control board. I found 25 feet of .032" dia. safety wire strung back and forth between nails sufficient. Attach the live wire of your plug-in cord to the voltage control and the ground wire to the hotwire saw. Mount the board up and away where there is no chance of it being touched when plugged in. This setup is easier than having to lug two car batteries around.
After realizing that I had an overabundance of 1/8" thick Masonite laying around the garage and none of 1/4" thickness, I tried gluing some of it together to achieve sheets of 1/4". I used regular white glue and weighted the Masonite down until it dried. I made my jigging and rigging templates out of it and found that it is more rigid and less prone to warpage than regular 1/4" thick Masonite. (Craig Dawson, #2685)
Below is a summary of epoxy handling info that I have compiled. This is a compendium obtained through discussions with technical reps of Shell Chemicals, Dow, Ciba Giegy, Applied Plastics and Fibreglas Canada:
1. Epoxies were never designed for use in the average homebuilders shop. All epoxy manufacturers stress the need to minimize personal exposure to their products. Obtain a Material Safety Data Sheet (MSD) from the manufacturer of your epoxy. This document, which must be prepared by the manufacturer by law, lists physical properties, fire hazards, disposal procedures, known health hazards and first aid treatments.
2. The main danger to homebuilders is exposure of skin to epoxy curing agents. Most curing agents are at least partially water soluble, and can be absorbed into the body through the skin. The effects can be cumulative until, once sensitized, very small exposure to the material - even breathing vapors - can start an allergic body reaction.
3. Wear gloves! Barrier creams are not enough. Butyl, latex or neoprene gloves are usually the best since they are the least permeable. Cheaper poly or vinyl gloves (including dishwashing types) are less effective. If using disposable latex types, change every hour or two. Also use disposable cotton liners. When changing gloves, pat hands dry of sweat with paper towels and dust dry with talcum powder. DO NOT USE SOLVENTS ON YOUR HANDS, since this removes natural skin oils, which provide protection. Solvents can also increase the rate of diffusion of chemicals through the skin. Do not wear rings or watches when using epoxy. Learn to take off gloves without touching outside surfaces with your bare hands. Finally, use a good skin cream to replace skin oils after you wash your hands.
4. Wear long sleeve shirts, full-length pants, socks and shoes. Start a routine with several sets of clothes. Wear each set only once between laundering in hot water. Uncured resin in cloth is just as bad the second time around.
5. Use disposable paper towels whenever possible to clean up spills (and do it promptly). That hardener you got on the screwdriver handle won't cure and will be around for many months waiting for you to pick it up again.
6. Overexposure to epoxy resin vapors can cause many of the same effects as chronic skin exposure, appearing as inflammation of the eyes, nose, throat and lungs. Wear a carbon canister respirator. These rubber mouth/nose masks have replaceable carbon cartridges, which absorb organic vapors as well as particulates such as sanding dust. Every industrial specialist I talked with considered a carbon canister mask essential for the typical homebuilder.
7. Dust and smell control is easier said than done. Arrange your work to minimize nooks and crannies where dust will accumulate. Put a doormat at the exit to your shop so you don't track dust into living areas. Arrange your laundry facilities so that you remove dusty clothes for laundering before entering living areas.
8. Keep in mind that epoxy, laminates and epoxy dust will burn. Some resin components have relatively low flash points and must be kept clear of open flames. If you find you need extra heat in your shop, avoid using kerosene type or radiant heaters. Do not smoke while using epoxies.
9. Do not mix epoxy components with other chemicals, including solvents or cleaners. Some combinations will react violently. (Robert Falkiner, #2015)
After the antenna cable has been soldered to the foil strips, a circuit test light should be used to test the connections prior to the glass layup over the antenna. (Ron Cross, #2397)
You can order a PDF or printed copy of QuickTalk #16 by using the Q-talk Back Issue Order Page.