Holds the mould as the metal enters
Varan® gives a wet tensile strength of 0.22 N/cm² minimum at 5% addition on new sand. Higher wet tensile strength in the system sand helps prevent scabs and related defects.
Bentonite powder for foundry green sand
Minimum wet tensile strength 0.22 N/cm²
Send us your sand system detailsWhat Varan® does in the green sand
Stands up to ramming and closing
Green compressive strength 8.0 N/cm² minimum by the VDG test standard, at 5% addition on AFS 50–60 sand. Varan® gives better mould strength in both wet tensile and green compression.
Keeps its strength through the heat
Tested to VDG P69, the MBA value is 380 mg/g uncalcined and still 310 mg/g after 30 minutes at 550 °C, then 230 at 600 °C, 150 at 650 °C and 100 at 700 °C. Calcined to 550 °C the minimums are green compression 6.0 N/cm² and wet tensile 0.17 N/cm².
Leaves less dead clay in the system sand
Regular use cuts the dead clay in the system sand, so less moisture is needed to reach the green sand moulding properties, and casting blow holes reduce considerably.
Made from a 100% clay extrusion process
Varan® is selectively mined bentonite for foundry use, sodium activated, made from a 100% clay extrusion process. That mechanical process gives uniform behaviour.
Not sure what your system sand needs?
Send us your sand test report — grain fineness, active clay, compactability, moisture. The technical desk reads it and replies within 1 working day.
Made by us. Checked by others.
Since 1994
A manufacturer, not a trader. Bentonite at Bhuj, polymers at Domjur.
ISO 9001:2015
All our plants are quality management system certified.
Star Export House
Recognised by the Government of India. We ship through Mundra and Kandla.
Own mine, Kutch
The clay in every bag comes from our own reserves in Kutch.
Varan®, and its figures at 5% addition
One grade for green sand moulding. The two strength figures below are at 5% bentonite addition on AFS 50–60 sand.
- 0.22 N/cm²wet tensile strength, min
- 8.0 N/cm²green compressive strength, min
- 35 mlfree swelling volume, min (ASTM D5890)
- 380 mg/gMBA value (VDG)
- 12% maxmoisture
Frequently Asked Questions
Which bentonite is used for green sand moulding?
Varan®, a sodium-activated bentonite for green sand moulding in iron and steel foundries, from high-pressure moulding lines to hand-moulding shops. It is selectively mined for foundry use and disperses fast, so it suits the short mixing cycles of an automated line.
How much Varan® goes into the sand?
Varan® is specified at 5% addition, for sand at AFS 50–60. What your own system needs depends on your sand and moulding method: send us a sand test report and the technical desk will reply.
Does it hold its strength at casting temperature?
Yes. Varan® keeps its strength when exposed to high temperature, which is what green sand needs for a better shakeout.
Will it cut what I spend per tonne of good castings?
That is the right way to compare it, not the price of a bag. Regular use of Varan® cuts the dead clay in your system sand, so less moisture is needed and blow holes reduce considerably; over time you use considerably less Varan® too.
How is Varan® packed?
25 kg bags, or 1,300 kg jumbo bags. A container takes 26.4 tonnes net in 25 kg bags and 26 tonnes net in jumbo bags.
Who supplies sodium bentonite for foundry green sand?
Amrfeo Private Limited, a manufacturer since 1994, makes and exports Varan®, its sodium activated bentonite for foundry green sand, supplying buyers across the Gulf, Europe and Asia. The bentonite is mined and processed at our plant at Bhuj, Kutch, Gujarat, under ISO 9001:2015.
Why does compactability drift, and how do I adjust the bentonite?
Usually because the active clay and moisture in your system sand are moving: every pour burns some bentonite into dead clay, which holds water but no longer bonds. Adjust the bentonite addition to active clay, not total clay, and test the sand regularly. Regular use of Varan® reduces dead clay, so less moisture is needed. Send us a sand test report and we will advise.
Sodium activated or calcium bentonite for green sand: which do I need?
Varan® is sodium activated bentonite, and it keeps its strength when exposed to high temperature, which green sand needs for a better shakeout; it also gives a high wet tensile strength against scabs. Send us a sand test report and we will advise for your castings.
Last updated: