Some time ago, there were questions on the CBA forum about the use of soy wax as a bullet lube ingredient. I looked into this and decided soy wax might have desirable properties. This was a low priority so it has been on the back burner for some time. Winter is a wonderful time for back burner projects to move to the front burner.
Soy wax is the darling of environmentalists who abjure candles made of (GASP) paraffin, a nasty petroleum product. Soy wax is an industrial product made by the hydrogenation of soybean oil. This process uses high-pressure hydrogen gas, possibly derived from coal and a catalyst like powdered nickel. Soy wax is a “natural” product, kind of like driving your electric car and recharging with “clean” electricity generated at a coal fired plant. However, we need to thank the environmentalists because soy wax is widely available in craft stores and on the internet to make “Natural” candles.
Soy wax is soft at room temperature and is suitable only for container candles. Higher melting “blended soy wax” has additives to raise the melting point; making it suitable for regular candles. Soy wax blends can have melting temperatures up to 180 F. There are no standards for “blended soy wax “so the additives can be anything.
Animal fats like tallow are primarily triglycerides, they are absent from commercial lubes because animal fats have problems. First: Animal fats have unsaturated components which become rancid over time. Second: The melting point can be undesirably low; they will melt on a hot day. Third: They can contain salt, which causes corrosion. Fourth: there is natural variability in which animal and even where on the animal the fat comes from.
However many successful homemade and historic bullet lube mixtures use beef tallow. Including those used by famous shooters like Donaldson, Beverage, Leupold and Pope as well as companies like Marlin and Smith and Wesson. The secondary components were hard waxes, the most common is beeswax. Several lubes were mixtures of only tallow and beeswax.
Beef tallow is mostly a triglyceride of steric acid. Soy wax is a pure triglyceride of steric acid. Therefore, soy wax should be a direct replacement for tallow in a bullet lube formulation. Soy wax is consistent, so repeated formulations can have the same properties. It does not have any unsaturated fat so it is stable and does not become rancid. Pure soy wax has a melting temperature of 120 to 125 degrees Fahrenheit.
The chemical purity of soy wax caused the first problems encountered. Soy wax has a very narrow range where it is pliable enough to use in a lube sizer. Once in the bullet grooves it has no tack, it crumbles and falls out. While tallow blends together with other waxes and oils, soy wax on cooling crystalizes out. The result, with jojoba oil, is a crumbly mass of crystals in an oil matrix. The matrix will not stay in lube grooves, preferring to fall out on the bench.
Mixing with beeswax, like in historic lubes, gives a harder product, but it is not a pliable wax, but again a matrix of crystals. The matrix fractures and does not adhere to lube grooves. Increasing the percentage of beeswax to give a useable waxy lubricant works, but this is a beeswax lube with a small percentage of soy wax and is very hard. I then had to add jojoba oil to adjust the hardness. The result is the beeswax/jojoba lube I tested before and published in the FS with a few percent soy wax, probably a good lube but not what I wanted.
I needed a liquid for the matrix to provide the desired tack so the lube would adhere to the grooves and have high viscosity to deliver toughness without brittleness. There are commercial products made for this purpose, heavy paraffinic oils, synthetic rubbers, and plastic polymers. Used as components of cosmetics and lubricants, these commercial products are only available in large lots.
Fortunately, there are oil-based products with large percentage of the desired compounds; they are engine oil additives to control oil burning in older engines. Available at automobile stores the choice is daunting. Many Like STP have zinc dithiophosphate, of no use in a bullet lube. Checking the MDS’s for composition, I picked Smoke-B-Gone (SBG) by Warren Unilube a heavy paraffinic oil, with viscosity modifiers. SBG is very thick and strings out in long threads when measuring. Testing showed 10 to 20 percent SBG provided the cohesion to hold the soy wax matrix together as well as giving excellent tack.
I tested soy wax with 20 percent SBG in 38 special loads and 357 magnum loads. The 38 special H&G 148 grain wadcutter at 750 fps was no surprise, just about any lube works at this pressure level, accuracy was excellent. The 357 magnum full loads with 158 grain Saeco RNFP plain base bullet at 1330 fps is a more demanding application, poor lubes will fail. Soy wax/SBG performed excellently, no leading and the accuracy was equal to the best this revolver has produced. There was considerable smoke and a generous lube star on the muzzle. The cylinder acquired a greasy coating after 50 rounds.
Soy wax/SBG mixtures have a narrow window of temperature for application in a lube sizer. Under 70 F 20 % SBG is too hard and too soft over 110 F. The upper limit is the melting point of the soy wax. The melting point can be increased by adding a higher melting wax: Castor wax or carnauba wax both mix well, carnauba melts slightly higher, 185 F than castor - 176 F but castor wax costs half as much. Either results is a broader temperature range. I may test these in the future.
I think soy wax has good potential as a bullet lubricant. It is widely available and inexpensive. A better matrix component is needed to give useful characteristics to soy wax lubricants, lithium grease comes to mind, but the possibilities are endless. Have fun experimenting.