Lumpy putty

[Zebra]

Several months ago I put some leftover hydrated lime into a tub, added water, stirred it into a thin paste, and left it thinking that it would make nice putty. It's gone solid at the bottom and when I stir it, goes into lumps, and is I fear, unusable. Should I have opened the tub and stirred it every now and again? Is it worth trying to save, even just to make limewash from? Or should I throw it away? What did I do wrong?

 

[TheForge]

Was it definately hydrated lime and not hydraulic? Hydraulic will slowly set in water but as you say hydrated shouldn't. If it was hydrated lime but it wasn't covered by a layer of water (just mixed) or the container wasn't airtight then it will have begun to cure.

You might still be able to use it for limewash regardless if you sieve it.

 

[MdB]

I've not mixed unused lime to a thin paste and then stored but I would expect it to be similar to a stored very thick lime paste which is what I've done. In this case, you end up with putty at the bottom (90% - stiff cream cheese texture) and lime water at the top (10% - milk). I pour off the lime water (but keep it for adding if really needed) and then use the putty for whatever I need it for.

If you end up with lumps, this suggests that you aren't using a whisk to mix it up as they won't last long with one of those.

 

[worms]

Zebra,

In the past I have done exactly what you did and produced excellent putty, so I am not sure where your problem lies. My fear would be that it was some form of hydraulic lime.

The only places my observations would differ from that of TheForge and MdB are that my putty bin is far from air tight and that doesn't seem to be a problem (the layer of water seems to do a pretty good job of keeping it protected from carbonation) and the fluid is crystal clear (not milk-like). If left undisturbed, after a while a skim of calcite forms on the surface, like thin ice on a pond.

Your "putty" should certainly not have carbonated in such a short time - are the lumps really solid (hard/dry) or like lumps of cheese?

 

[MdB]

The only places my observations would differ from that of TheForge and MdB are that my putty bin is far from air tight and that doesn't seem to be a problem

I wouldn't say my tubs were completely air tight. It only needs to be good enough to not dry out.

and the fluid is crystal clear (not milk-like). If left undisturbed, after a while a skim of calcite forms on the surface, like thin ice on a pond.

Yep, I agree with that and I wasn't clear above. The fluid is clear until disturbed.

 

[Zebra]

Was it definately hydrated lime and not hydraulic?

Definately hydrated and not hydraulic. Perhaps it was already a bit old when I added the water to it though.

Are the lumps really solid (hard/dry) or like lumps of cheese?

Yes, like lumps of cheese - ah, so is that normal?

putty at the bottom (90% - stiff cream cheese texture) and lime water at the top (10% - milk). If you end up with lumps, this suggests that you aren't using a whisk to mix it up as they won't last long with one of those.

Yes, like stiff cream cheese at the bottom, that is what I got. Ah, remixing with a whisk, is that what it needs to get the lumps out?

Oh good, so it might not be a wasted effort after all. Thanks.

 

[DJH]

Did it freeze at all?

 

[middi]

Hydrated lime putty will keep a very long time ( even in an open top container) as long as it is always covered with a film of water and never allowed for this water to dry out by frequent inspections and topping up if required.

Middi

 

[MdB]

Yes, like stiff cream cheese at the bottom, that is what I got. Ah, remixing with a whisk, is that what it needs to get the lumps out?

I'm a bit interested in what you are going to use this for as you were talking about turning it into a thin paste earlier. Is this for limewash? If so then a whisk will sort it out for you. If you are going to use it for putty made mortar then I would put far less water into the hydrate to start with. You only want just enough so you can sort of stir it. When you come to use it, pour off the lime water on the top and the scope out the putty and add to your sand. I wouldn't bother mixing first - far too messy and hard work. Just shove the cream cheese in with your sand and mix well with either a drum (for ages) or with a whisk. Get a decent whisk though as I've been through three so far and an SDS drill with gearbox.

 

[Zebra]

Thanks. I was just kind of keeping it. Limewash, yes perhaps one day I will want to decorate indoors. Mortar perhaps, there is still some pointing to do. Dance round the tub on a full moon? Ooh, what else can you do with lime?

 

[MdB]

Ooh, what else can you do with lime?

Take it down the pub and get plastered...

 

[plasticpigeon]

I picked up some lime plaster from Matthew C which was very stiff at the bottom. I don't know how old it was, I think maybe a year, but some good bashing about and it was nice and smooth again!

 

[MdB]

I picked up some lime plaster from Matthew C which was very stiff at the bottom. I don't know how old it was, I think maybe a year, but some good bashing about and it was nice and smooth again!

That is something I've noticed too. The bottom always seems stiffer / drier than the top.

 

[Moo]

I've noticed exactly the same thing with the almond butter* they sell in our local organic grocer's shop.


* like peanut butter, but tastes different.

 

[tobydog]

Given that Zebra turned it into a thin paste, isn't it simply just a case of settlement? The particles have displaced the water at the bottom in the same way as paint settles when left for a while?. Obviously this is unlikely to happen with a normal stiffer putty mix.

 

[Flyfisher]

That would be my guess. I can't see how it could 'go off' by carbonating when it is fully underwater, even though it might settle into lumps.
A good remixing should see it right.

 

[LadyArowana]

I picked up some lime plaster from Matthew C which was very stiff at the bottom. I don't know how old it was, I think maybe a year, but some good bashing about and it was nice and smooth again!

I cannot believe that we have stayed on topic even after the comments in this post, Mr P must be dozing again :lol:

 

[Moo]

But the thread's about lime, milady. PPUKers can't be expected to get frivolous in a thread dealing with a Really Important Topic.