Re: SB: Slaking quicklime

[CALXA@aol.com]

Hi Karen,

Be careful. If you can send me a fax number I'll send you some good 
instructions/precautions on slaking quicklime..

I am surprised you have 50 # bags of QL , as industry practice uses 90 # bags 
of quicklime; and 50 # bags of hydrated lime. Just want to be sure which lime 
you have.
Also, is it Hi- calcium or Dolomitic quicklime?

Slaking of quick slaking hi calcium reactive lime is different from the 
slaking of Dolomitic QL. 

Excess water will "Drown" the lime and make a  grainy hydrate putty, not 
suitable for plaster/stucco/mortar. Also "Burning" (allowing the slaking 
porocess get too hot) will also produce an inferrior grainy hydrated 
paste/putty.

So, test a small amount of your QL before committing to doing a bag full. 
Place severa pieces of the QL in an open pan, and lightly sprinkle with 
water. How quickly does it begin to swell, and produce steam...//.

*Immediate reaction is quick reactive lime

*If its 5-10 minutes before anything happens, its slow reactive.

Quick reactive lime is added to the water. Start with only a gallon or two, 
and have additional water available to add to the slaking process. Pour in 
some quicklime , just about equal to the level of water. As the QL begins to 
swell and produce heat, add water to keep the mixture just below the boiling 
point, and stir with a hoe. As you add more water to keep the temp down, also 
add more QL ( small amounts) to again keep the temperature about 190 Deg F - 
try to not let it boil...Continue this practice of adding QL & water & 
stirring till you have completely slaked all the QL.

Then add sufficient water to cover the putty, and store it this way until you 
use it. Don't pour off and discard the layer of water, but save it for 
tempering the putty as needed when applying the plaster/stucco, and palce 
unused water back on top of the putty for storage. Cover the barrell to keep 
out air (Carbon Dioxide).

For slow slaking QL ( Dolomitic or Hard burned Hi Cal), you use much less 
water. Adding just enough water to start the slaking process, then adding 
water to a spread out layer of slaking QL, trying to keep the heat uniform 
and as hot as possible ( still below 190 degF)...This material slakes much 
slowly than Hi Cal QL, and uses less water as the heat generated is less, and 
less water is boiled off. Stir, Stir, Stir.

It is important in both cases to keep the temperature controlled...not too 
hot, not too much water, so the process progresses evenly, producing a "Fat" 
plastic putty. It should be like soft butter.

Ideally, after slaking, you will age the putty for as long as you can before 
using. This improves the plasticity of the putty, and helps to insure 
complete slaking of hard burned particles of QL. Keep stored Putty under 
water.

If you have resulting hard partcles, you will need to pour the putty thru a 
screen...like a screen door size, to remove the un-reacted particles... If 
not removed before use, they will eventually slake, and swell, "popping " out 
of the plaster/stucco/mortar.

This is a learned skill, so practice a little before ruining all your QL.... 

And DO BE Careful. QL can generate temperatures approaching 500 + Deg F in 
the presense of moisture, catching paper and wood on fire, and causing 
serious burns to the skin. ( as long as there is liquid water, the 
temperature will not exceed  boiling temerature)
So have plenty of water available. You may also want to have some vinegar - 
used to neutralize lime if you get on sensitive skin.

Use Goggles, long sleeve shirt, gloves, boots, long pants, etc....

Mankind has been slaking QL for thousands of years, without damage to them 
selves... It is not a "Hazardous Substance", or poison, of poisonous fumes, 
etc, but it  can be dangerous if handled improperly. QL dust/ particles 
falling on the skin, or in the eye can be very damaging due to the heat 
generated, so be careful. 

Working with lime will remove oil from the skin, so wash good, and apply hand 
lotions.. Wear clean clothes daily.

Be Careful, Have Fun, Be Amazed.

Harry Francis
Elliston, VA.

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