Gilsonite History & General Information

The mineral now know as Gilsonite was discovered in the early 1860's, but it was not until the mid-1880's that Samuel H. Gilson began to promote it as a waterproof coating for wooden pilings, as an insulation for wire cable, and as a unique varnish. Gilson's promotion of the ore was so successful that, in 1888, he and a partner formed the first company to mine and market Gilsonite on a commercial scale.
Originally, Gilsonite was sold as "Selects" and "Fines"; the law softening point ore with conchoidal fracture was known as "Selects". The higher softening point ore with a pencillated structure was known as "Fines". Selects commanded a higher price than Fines because of its better purity, good solubility, and usefulness in the paint, stain, and varnish industries.
Time and technology have changed this classification system. Processing of Gilsonite now removes most of the inert contaminants and newer, more powerful, solvents make the higher softening point grades more interesting to the user. Today, Gilsonite is graded by softening point (a rough measure of solubility) and particle size. All grades carry a degree of quality far superior to those first small amounts of crude Gilsonite marketed in the 1880's.

Gilsonite Technical Information

The information in these pages is based on laboratory evaluation and field experience. It is correct to the best of our knowledge. Recommendations are made without warranty or guarantee and buyer assumes all risk and liability.

Gilsonite Physical Properties:

Gilsonite Molecular Structure:

A variety of sophisticated analytical tests have been run on Gilsonite to characterize its unique properties. For reference, the test methods include vacuum thermal gravimetric analysis (TGA), nuclear magnetic resonance (NMR), Fourier transform infrared spectrometry (FTIR), vapor pressure osometry (VPO), high performance liquid chromatography (HPLC), rapid capillary gas chromatography (RCAP), and several fractionation techniques. H/C ratios and NMR analysis indicate the presence of a significant aromatic fraction. Most of the aromatics exist in stable, conjugated systems, probably porphyrin-like structures that relate to the geologic source of the product. The remainder of the product consists of long, paraffinic chains.
A very unique feature of Gilsonite is its high nitrogen content, which is present mainly as pyrrole, pyridine, and amide functional groups. Phenolic and carbonyl groups are also present. The law oxygen content relative to nitrogen suggests that much of the nitrogen has basic functionality. This probably accounts for Gilsonite's special surface wetting properties and resistance to free radical oxidation.
The average molecular weight of Gilsonite is about 3000. This is very high relative to other asphalt products and to most synthetic resins. This may relate to Gilsonite's "semi-polymeric" behavior when used as a modifying resin in polymeric and elastomeric systems. There is some reactive potential in Gilsonite. Crosslinking and addition type reactions have been observed. Gilsonite is known to react with formaldehyde compounds under certain conditions.

Gilsonite Compatibility

Gilsonite is compatible with Microcrystalline and Paraffin Waxes, Petroleum Resins and Oils, Rosins, Tall Oil Pitch, Vegetable Oils (Linseed, Soya, etc.), Petroleum Process Oils, and Petroleum Asphalts.

Gilsonite Compatibility with Commercial Resins

The following is a general guide to the compatibility of Gilsonite resin in common film-forming and elastomeric systems. Because Gilsonite compatibility can be influenced by variations within a resin/elastomer class and by other components in a formulation, it is good practice to verify Gilsonite compatibility in the specific formula of interest.