No doubt that carbon tool steel and 3000 rpm grinders are not entirely happy bedfellows. Even 1500 rpm slow grinders with white wheels need care to avoid bluing. Dipping the tool in water is either too late (already blued, or cracks from thermal shock) or very messy. Enter Kool Mist....
This device bathes the grinding area in very cold damp air. Rather like a spray gun, it gives control of both air and coolant (usually plain water). Evaporating water cools the air, which delivers just enough water to keep the tool damp - no floods of water. The jet is held on the grinder by a magnet and flexibly mounted to allow you to aim it at a tangent to the wheel. The usual draught from the wheel also helps deliver the cooling where needed. It certainly delivers an icy feeling to the hand (but carefully, this is how you set it up) It can deliver plenty of coolant if you wish, but not really needed for tool grinding (and messy)
The device can be bought complete with tanks etc, but mine came as a matchbox sized block of ali with holding magnet and air control knob, a flexible stay-put spray head, short 1/8" air hose, and 1/4" pvc coolant tube with a litttle intake filter (reminded me a bit of garden sprayer parts, but the kool mist is made of ali brass and pro snaploc hose). You provide your own "tank" of water. As you can see, 1/8" air hose suggests a very modest air consumption. I only wish I'd found this years ago!
To view, look on amazon.com and search for "kool mist". I got mine last year, before the £ fell against the dollar, cost about two LN plane blades, but these rates will change again.
P.S.Engineers can add a soluble lubricant / inhibitor safe for spraying if used on machine tools.
This device bathes the grinding area in very cold damp air. Rather like a spray gun, it gives control of both air and coolant (usually plain water). Evaporating water cools the air, which delivers just enough water to keep the tool damp - no floods of water. The jet is held on the grinder by a magnet and flexibly mounted to allow you to aim it at a tangent to the wheel. The usual draught from the wheel also helps deliver the cooling where needed. It certainly delivers an icy feeling to the hand (but carefully, this is how you set it up) It can deliver plenty of coolant if you wish, but not really needed for tool grinding (and messy)
The device can be bought complete with tanks etc, but mine came as a matchbox sized block of ali with holding magnet and air control knob, a flexible stay-put spray head, short 1/8" air hose, and 1/4" pvc coolant tube with a litttle intake filter (reminded me a bit of garden sprayer parts, but the kool mist is made of ali brass and pro snaploc hose). You provide your own "tank" of water. As you can see, 1/8" air hose suggests a very modest air consumption. I only wish I'd found this years ago!
To view, look on amazon.com and search for "kool mist". I got mine last year, before the £ fell against the dollar, cost about two LN plane blades, but these rates will change again.
P.S.Engineers can add a soluble lubricant / inhibitor safe for spraying if used on machine tools.
) you can avoid the water problems altogether with a "Cold Gun" type setup. 
