Foundry Gilsonite: Frequently Asked Questions

How much gilsonite replaces sea coal?
Usually less gilsonite is needed than sea coal because of its higher volatile matter and lustrous carbon yield. The exact ratio must be found by plant trials.

Will it increase gas defects?
Only if overdosed. Control LOI and volatiles.

What mesh size is best?
100–200 mesh for most green sand systems.

Can I blend it with bentonite?
Yes, pre-blends are common.

What about sulfur?
Choose low-sulfur grades for ductile iron.

How is it packed?
25 kg bags or 1 MT jumbo bags.

What mesh size is best for green sand?
100–200 mesh is the most common starting point.

Can gilsonite be used with bentonite pre-blends?
Yes. Many blend producers use it as the carbon component.

Does gilsonite increase smoke?
Used at the right dosage, total smoke can be similar or lower than with higher dosages of coal additives.

How do I know if I am overdosing?
Rising LOI, gas defects and lustrous carbon folds are typical signs.

Is it suitable for steel castings?
Only where carbon pick-up is acceptable.

See foundry grade gilsonite and gilsonite in foundry sand.