Life expectancy of unused NHL

[tobydog]

I recently bought a bag of NHL 3.5 and I'm getting through it slowly as I work my way round the house patching up different areas. I keep it in the shed with the top turned down but no other special treatment. Unfortunately the base of the bag got damp last week during the heavy rain and winds when the shed door flew open, however, the majority is still in fine powder form.

I read this morning that once a bag of NHL is opened it should be used within a few days because the moisture it will absorb from the atmosphere will affect it's quality. Can someone please confirm if this is true and, if so, am I really losing much quality if it's still powder?

If it is true then maybe I'll be better off switching to pre-mixed putty, plus a pozzolan as required. The wall I'm currently working on will be forever damp hence the hydraulic set requirement.

Thanks

 

[JohnB]

Is it worth keeping it in a sealed plastic bucket? You get plenty of those if you buy lime putty!

 

[robgil]

Afew days? Thats not right, I have used NHL from an open bag thats been sat there for months and months. It takes years and years for lime to fully carbonate from the atmosphere.

 

[tobydog]

I was surprised too but I think the issue might be more with the initial set from moisture in the atmosphere than carbonation through CO2 absorption. It came from the link below under the Storage part.

http://www.bostonrestorationsupply.com/nhl35.html

 

[MdB]

Yes the damp from the atmosphere will cause the lime to start to carbonate as soon as you open the bag. The question is how quickly this happens and when does it become an issue? The solution is to test the lime before use and measure its alkalinity - something I've never done but I do believe others here have and hopefully will explain what to use and how to do it.

 

[robgil]

I was surprised too but I think the issue might be more with the initial set from moisture in the atmosphere than carbonation through CO2 absorption. It came from the link below under the Storage part.

http://www.bostonrestorationsupply.com/nhl35.html

Well to be fair they would say that, more waste = more bags of lime sold. Ive used lime that has been sat in my shed for a very long time and its been fine. If the bag is damp however I might think twice or at least mix it in with some new stuff.

 

[tobydog]

Thanks for the responses. I'll seal it in a plastic bag for now. It's been open for over 6 weeks now and I've not noticed any difference but having said that, my batch mixing started off a little inconsistant so it's hard to tell. One of my simple school boy (novice) errors was to not realise that 1:3 with wet sand is not actually 1:3. Hopefully it will still breath although until I apply the lime wash the plinth render is looking a bit like a patchwork quilt :roll: .

 

[Zebra]

One of my simple school boy (novice) errors was to not realise that 1:3 with wet sand is not actually 1:3.

Is the wet sand more sandy or less sandy than dry sand, and how much does it affect the ratio? I've not been accounting for this in my mix, oops.

 

[robgil]

One of my simple school boy (novice) errors was to not realise that 1:3 with wet sand is not actually 1:3.

Is the wet sand more sandy or less sandy than dry sand, and how much does it affect the ratio? I've not been accounting for this in my mix, oops.

I've never bothered, I think you can look into it too much , it isnt an exact science.
I have always measured my ratio's by the spade full when mixing up and never had a problem.

 

[MdB]

I don't worry as my sand is never bone dry which is when the volume goes up a bit I think.

The one time I do worry is when using putty. A wet sand + putty mix with no extra water can end up too wet and has to be left to stand for a day or two to settle out.

 

[tobydog]

I wouldn't worry Zebra - the guys are right. Even thrown together roughly it shouldn't make a huge difference. The issue I had was that I was throwing it together in a bucket and I realised later that because the sand was quite damp in was clumping together and I was creating big voids. Just careless on my part. It's now getting thrown together carefully!