JT40/JT40 All Terrain Operator’s Manual Systems and Equipment - 159
Drilling Fluid
Bentonite
Bentonite is a dry powder. When properly mixed with water, it forms a thin cake on bore walls, lubricating
the bore, keeping it open, and holding fluid in the bore.
Some things to remember when mixing bentonite:
• Use clean water free of salt, calcium, or excessive chlorine.
• Use water with pH level between 9 and 10.
• Use water with hardness of less than 120 ppm.
• Do not use bentonite containing sand.
• Mix bentonite thoroughly or it will settle in tank.
• Do not mix bentonite to a funnel viscosity of over 50.
For information on measuring funnel viscosity, see “Funnel Viscosity” on page 161.
Mixtures
Bentonite does not mix well in water containing polymer. To use both, mix bentonite first, then add polymer.
When adding other products follow the order listed below.
General mixing order:
1. Soda ash
2. Bentonite
3. Polymer
4. Con Det
®
The Bore-Gel
®
system contains premixed bentonite, polymer, and soda ash. Use approximately 15 lb/100
gal (7 kg/380 L) in normal drilling conditions, up to 45 lb/100 gal (21 kg/380 L) in sand or gravel and up to
50 lb/100 gal (23 kg/380 L) in rock.
IMPORTANT:
• If chemicals are added in the wrong order, they will not mix properly and will form clumps.
• If tank contains bentonite/polymer mix and more drilling fluid is needed, completely empty tank and
start with fresh water before mixing another batch.
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