Well to satisfy my own curiousity, I decided to perform a gas immersion test on the most popular epoxies. I chose 6 epoxies; Loctite E-120 HP, Marine Tex white, Bluemagic Plastic Tank repair, J-B weld, J-B Marine weld, and Permatex Motoseal Ultimate gasket maker. Not tested were Seal-All, Loctite Stik'N Seal oil and gas, and Versachem heavy duty fuel tank repair (due to either low termperature toleration or lack of stiffness). Test and control sample (thermoplastic, but these results are independant of materials) pieces were glued together following manufacturers instructions and allowing 48 hrs to cure in air. Test samples were then submerged in 93 octane gas and left alone with an occasional swirl. The test was started on 31 Oct 2015 and conducted for 133 days or 3200 hrs. The results were that NONE held up except Marine Tex white. Pic 1 shows the test setup. Baby food jars were used for the gas samples. Pic 2 shows what was not tested. Pic 3 shows the results. The BlueMagic plastic tank repair did not adhere in the control sample. All other control samples stuck together very well. All control samples in air were super hard and could not be separated except for Bluemagic. All test samples except Marine Tex came apart when exposed to gas. Of these failed ones, the 2 pieces pulled apart easily with finger tension. All failed adhesives had the consistency of gum, rubber, or silicon like. All easily crumbled or fell apart just by figerrnail pressure. The Marine Tex test sample could not be separated with finger pressure and the expoxy was still super hard. Even with adhering to aluminum, the failed adhesives would in no way remain intact. I was most surprised by both J-B weld results.
Good info. I used to use Marine Tex a lot but it takes a little more effort to get it. Also that stuff has been around forever (50 + years.)
JB Weld is the Edsel of epoxies. Marine Tex has been an excellent epoxy and I've used it for decades. Not sure if they've change the formula over the years or not. Good test!
That's correct, PC11 does, used it on the tank of my 928 Porsche 5 years ago without a problem. Also Permatex makes a gasoline tolerant RTV that goes on like thin RTV, almost liquid, and and cures like 90 durometer rubber. used that a fews times with good results.
