lime questions

[coffutt]

I've recently started uses calcium hydroxide in 2 recipes and while I've had predictable results so far, I do have a couple questions moving forward.

Will the quality of lime degrade in an aqueous solution over time? Does it loose its ability to increase alkalinity like when the powder absorbs moisture?


I've been sprinkling the powder on the loose mash and am also wondering if I use a liquid solution, is it recommended to add that after mash in as well?


And, with an RO base, does using calcium hydroxide cause any issues with calcium precipitation or is that only a problem with high bicarb water? Every recipe I have uses calcium sulfate and/or chloride added to the HLT. Am I neglecting the calcium in those additions by adding lime?

thanks for any help

 

[ajdelange]

Will the quality of lime degrade in an aqueous solution over time? Does it loose its ability to increase alkalinity like when the powder absorbs moisture?

Take some milk of lime. Let it stand until clear then decant some of the clear liquid. Take a straw and blow some of your exhaled breath through the clear lime water. This should
A) Remind you of grammar school science class
B) Answer your question.

I've been sprinkling the powder on the loose mash and am also wondering if I use a liquid solution, is it recommended to add that after mash in as well?

Powder and solution are handled the same way but it is recommended that they both be dissolved in water and added to the strike water - not the mash.

And, with an RO base, does using calcium hydroxide cause any issues with calcium precipitation or is that only a problem with high bicarb water? Every recipe I have uses calcium sulfate and/or chloride added to the HLT. Am I neglecting the calcium in those additions by adding lime?

That's with bicarb or phosphate.

 

[mabrungard]

Yes, as AJ cryptically responds, lime water solution strength will degrade due to the presence of CO2 in the air...or your breath. It's probably best to mix a fresh solution prior to use, if that is the way you want to use it.

Adding the calculated amount of lime directly to the strike water will ALWAYS be better than sprinkling the powder over the grist since you can better assure that the addition is well distributed throughout the mash.

Adding lime to RO water at the typical low levels needed for mashing strike water will not create the calcium precipitation that you're concerned with. The calcium content of the water would have to be much higher and the pH would have to be driven much higher than is typical for strike water.

 

[coffutt]

And how could I test the purity, or at least monitor the effectiveness besides adding "more next time" when the mash pH has settled lower than the previous batch?

 

[mabrungard]

And how could I test the purity, or at least monitor the effectiveness besides adding "more next time" when the mash pH has settled lower than the previous batch?

That is a distinct problem with lime. You can't count on it being at 100% purity. The way around that is to create the saturated lime solution and use that fresh, saturated solution as your dosing charge. The problem is that I haven't worked through the chemistry calculations on that solutions and haven't included in Bru'n Water.

It's a somewhat simple calc that is temperature dependent, but I haven't worked through it since I don't believe that many brewers rely on lime in their brewing. I've switched to baking soda for the few brews that require mashing water alkalinity. Its much more consistent and reliable.

 

[ajdelange]

And how could I test the purity, or at least monitor the effectiveness besides adding "more next time" when the mash pH has settled lower than the previous batch?

One tests the purity by making a solution and doing a full up alkalinity test IOW titrating first to pH 8.3 (the result is called the P-alkalinity) and then to pH 4.3 (the result is the M or total alkalinity). If none of the lime has converted the P and M alkalinities will be the same. An appreciable difference between P and M indicates conversion to calcium carbonate. Note also that lime powder will convert if stored long enough (there are water and CO2 in the air) so that even if making a fresh solution each time one need to check purity from time to time. You really don't want CaCO3 lingering in your mash or beer.