Putty lime gets hardened under water

[altsay]

Hello. I just made one bucket of lime putty out of hydrated lime powder the other day. By following the regular procedure, putty was in a creamy consistency right before i filled the remaining few centimeters with water and closed the lid off.

Earlier today, i lifted the lid up and poked the putty with a long screwdriver or i should say i struggled to do it as it was "suspiciously" hard underneath the layer of water.

I could only made as much 10cm deep in the bucket and as i was poking it on various spots, some putty with the regular creamy consistency has come to the surface.

I was also able to smush the lumps in my hand pretty easily. So that gave me some hope but all in all, is this all normal? Or it went wasted?

 

[paulc]

When ever I open up a tub of putty, after pouring the water off, it needs a darned good mix. The bottom of the tub can often feel rock solid, and the paddle mixer struggles sometimes.
I'd suggest giving your tub a good mix before condemning it.

 

[aockenden]

It’s either normal compaction / settling resulting in denser putty in the deeper layers of the container, or you actually got hydraulic lime instead of non-hydraulic lime which has started to hydraulicly set underwater. My guess is the first one.

In general, don’t mistake putty compaction and higher density for carbonation. Compacted dense putty is hard to mix into mortars / plasters but it makes controlling the moisture in your mixes much easier. I’ve come to love the really dense compacted putty near the bottom of my barrels.

 

[altsay]

Is the carbonation process too unforgiving in a way that exposing it to air for a few minutes would render it useless?

Because i might have done just that as there was no water to add and i paid a visit to the nearest tap

 

[aockenden]

Is the carbonation process too unforgiving in a way that exposing it to air for a few minutes would render it useless?

Because i might have done just that as there was no water to add and i paid a visit to the nearest tap

Absolutely not possible as an explanation. Carbonation of even a fairly thin layer of lime putty based plaster takes many weeks / months to complete. A deep pile of it sitting in a barrel would take an extremely long time to carbonate deeper than even a couple centimeters.

I’ve had barrels of lime putty accidentally spring a leak without my knowledge. Suddenly I checked on it and all the water had drained out and the putty had been sitting exposed to air for some weeks. Only maybe the surface 3-5 mm of the lime putty had actually carbonated into a sort of “crust”. Once you broke through that crust I got back to dense, but creamy uncarbonated putty underneath.