HELPFUL HINTS SILICONE
CAULK
By Edward B. Oliver, EAA 7911 P. O. Box 1667, Daytona Beach, Fla. I have found many uses for a tube of Silicone Rubber Bathtub Caulk put out by Dow Corning. This can be purchased for about $1.95 for a three ounce tube at most any hardware or department store. When squeezed onto something, it solidifies with all the properties of rubber and adheres to any surface. A medium application of it sets up in an hour or so. It is white in color, and I understand that this material can also be purchased in clear, aluminum, or black. They also advertise a red selastic that will withstand temperatures up to 600 deg. F. Any surface to which we apply this material is first quickly wiped off with a rag moistened with lacquer thinner. The material is applied directly from the tube to the surface. It begins to solidify right after contact with air. We used to have a lot of trouble with cowling chafing where the aluminum sections come together. Some manufacturers cement, rivet, or staple cotton braiding or synthetic rubber ribbons to one of the two surfaces. The braiding soaks up oil and makes a mess . . . the rubber wears and creeps and has to be replacd often. We find that the application cone that is supplied with the selastic can be cut off to a half-moon shape so that the material can be smoothly applied to one or both surfaces. As soon as the material solidifies, you have a perfect antichafing strip. We have replaced the rubber strips that go on the edge of the wing and tail root fairings of our "Apache." First we remove the fairings and apply a thin layer of selastic on the inside edge of the fairing and make sure that it goes slightly beyond the edge all around so that the fairing cannot make metal to metal contact when reiru^alled. After this solidifies, we cover the surfaces where the fairing is to be applied with wax paper held in place with masking tape. Now we install the fairing and make a fillet between the fairing and the main body by using the tube as per directions on it for caulking a tub. When this solidifies, merely remove the wax paper. The waxed paper keeps the material from adhering to the main body of the airplane. Any time one of our electric cords on a drop light or electric drill begins to crack the rubber insulation at the plug or appliance end, we merely smear on a little tub caulk and it is better than new. We make up our own cannon plugs, etc., by arranging
SMALL
ANNEALING
connectors and connecting them the way we want them. We then coat the connectors with selastic, and it is a perfect insulator. If a rubber composition fuel tank becomes porous and seeps, it cannot be patched with the manufacturer's kit. An otherwise good tank costing $350.00 on up can be as good as new again by smearing it very lightly over the porous area with selastic. While this material seems to do wonders and seems to be absolutely unaffected by contact with fuel or oil, I was amazed when I used selastic for sealing an old compass to find that some AN surplus compass fluid that I used swelled up the selastic and made it useless. I understood that compass fluid was specially refined kerosene . . . it smells like kerosene. I would think that fuel would have an effect on the selastic worse than the kerosene. This one thing perplexes me about selastic. I do not want to push any product by brand name, but I do not know of any other brand that does the jobs that I mentioned. Twice I had gotten another brand of tub caulk by mistake because the tubes appeared to be similar. I found the material to be very different, and I would be afraid to use it in the applications that I have mentioned. I have even made permanent cylinder baffle repairs with tub caulk. When a crack appears, merely smear a little selastic along the cracked area on both sides, or make a fillet of it if the crack appears in a corner. It usually will not crack further because it is held firmly, yet flexibly, deadening vibration transmission. Selastic is perfect to seal cabins, etc., and make them water tight. I thought for a while that it might also be good for sealing around the windshield and act as a cushion to allow expansion. However, Cee Bailey, windshield manufacturer from Long Beach, wrote me that selastic applied to plexiglas will craze it. So I guess that is out. I recently had a problem where a boot was used to seal water from entering a compartment in an amphibian where the rudder cable entered through a hole in the compartment from outside. The boot flexed more on one side than the other, causing one side of the boot to collapse and chafe against the cable. It would have been no time at all before the boot was cut through. I merely smeared a small amount of selastic inside the boot with my finger while the boot was stretched out. This extra thickness made the boot stiff enough to keep it from collapsing against the cable. All in all, I would say that this wonderful material in a little tube has saved our little shop over $1,000.00 so far this year.
By Eugene J. Cepelones, EAA 27376 Long Beach, St. Leonard, Md.
OVEN
In building my Pazmany PL-1, I found that I had to have an inexpensive and simple way of annealing 24 ST3 aluminum, or reannealing it when it became work hardened in some cases. One morning, while watching my wife make waffles, the thought struck me to buy a single waffle grill. I removed the top and bottom grill plates, and placed the aluminum between the two heating elements as shown in the picture.
The aluminum is moved in stages as it anneals, then air cooled and shaped to its desired form. Scrap pieces of
aluminum can be used to get the feel of it. This system does a good annealing job and is quite handy to have around. 34
SEPTEMBER 1968
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