Have I got the wrong sand?

[Sue Wilkinson]

Hi, I don't have a mortar mixer and so I cheat with my lime work and buy ready mixed. It lasts ages, can be knocked up and used quickly and comes in convienient sized bags. However, for my dreaded garden wall re-build I thought I'd use hydrated lime to save money.

I have soaked the hydrate to form a putty. Today I mixed it with sharp sand. But I couldn't get it to go sticky no matter how much mixing I gave it. I've used what I mixed up today as an experiment, but its nothing like the wonderful ready mixed stuff. I only used sharp grit sand because in the bag it looked to contain all sorts of size particles like the ready mixed stuff (and a bit of pozzolan) should I have included anything else like a soft sand as well?

Why do you think its not going sticky and workable? I could hardly get it to stick to my trowel. Resorted to picking it up in handfulls!!!!!

Sue

 

[biffvernon]

I have soaked the hydrate to form a putty. Today I mixed it with sharp sand. But I couldn't get it to go sticky no matter how much mixing I gave it. Sue

Maybe you just did not mix it enough - it does take a long time and then suddenly its there. Add liiiitle bit of water if you have to. In this weather the sand may be drier than you guessed. I wouldn't bother with the soft sand.

Frankly, I now usually mix the dry hrdrated lime powder with the aggregate before adding the water, never mind the putty stage. It is so much easier to mix and I'm not convinced I can tell the difference in the finished product. (Ducks to avoid flying masonry hurled by lime purists.)

 

[worms]

Sue,

I mixed two loads of mortar by hand yesterday (arms ache today!). I had intended to try Biff's approach by mixing dry first, since it sounds easier, but the local source of hydrated lime was closed on Saturday afternoon when I went to get the bagged lime. So it was back to the putty.

The first batch I used two parts grit/sand (dug up from the side of a local river), one part putty and one part sandy subsoil from the garden - which is very very fine. This one was almost impossible to mix - the fine stuff seems to make the lime/grit mix form into marbles.

For the second batch I left out the subsoil and just had three parts grit/sand and one part putty. This mixed easier but wasn't such a pleasing colour. For both batches I added a little of the fluid off the top of the putty bin right at the end of the mixing and that seems to make a huge difference to the consistency.

Are you sure your putty is OK? Was the original lime OK? Mine has soaked for nearly a year and is so thick it needs to be cut from the tub with a trowel.

 

[Sue Wilkinson]

Thanks Worms, my putty is thick, but its only a few days old, Jane Schofield (I think its her book anyway) says that if you want to just get on and use hydrated lime then 24 hours soaking is enough, although longer is better. Mine had a bit longer than that, and I did have to chop it out of the tub, rather like a heavy blancmange consistency.

I got that marble type effect with it. It took a heck of a lot of working to get rid of it. Perhaps, as Biff says, I just didn't go long enough but it was taking up so much of my working time and I was getting worn out.

I shall try more later in the week and see how it goes. In frustration I think I added too much water to the mix.

Sue

 

[biffvernon]

In days of old... Sometimes quicklime was slaked, mixed with aggregate and built with whilst still warm.

Some say that Chateaux-neuf-du-Pape '84 is better than beaujolly nuvo, but in my experience they both work.

 

[Sue Wilkinson]

Gosh, I wouldn't have wanted to get that on my hands!

Sue

 

[biffvernon]

No, Sue, you drink it, not wash with it.

 

[biffvernon]

Oh! you mean the quicklime.

 

[Sue Wilkinson]

Ho, ho!

Don't worry, I know just what to do with almost any type of wine. :lol:

I remember slaking some lime last year on a course, then leaving it in a pile on a board, covered with the sand and some water. It steamed. Next day we came in and knocked it up and it was ready for use, although I seem to recall we didn't need it, so we stored it away for the next group.

We were told that this was a regular method of preparing the mortar on Victorian building sites. Last thing in the working day a labourer would go around the various sites and make up these heaps ready for next day.

Its facinating stuff lime, its a pity that so much general knowledge about it has been lost over the last 50 years or so. We are having to reinvent the wheel in places I guess. We have the perfect theory because we understand the science, but people being people, we've probably lost a lot of the labour and time saving short cuts our ancestors developed with the material to make their lives easier.

Sue

 

[Gervase]

Mixes made with bag lime do need a fair bit of knocking up before they get sticky. I know it's a bore and a hefty capitaol outlay, but if you haven't got a fit, strong assistant to do the mixing for you, invest in a drum mixer.
Belle and Clarke both make drum mixers, starting at around £140. Belle are better than Clarke, although slightly dearer. You may find a reasonable one on eBay.
Go for electric rather than petrol if you're just after the one mixer, as petrol mixers are not good for indoor use (for plastering and the like).

 

[Sue Wilkinson]

but if you haven't got a fit, strong assistant to do the mixing for you, invest in a drum mixer.

No, no fit, strong assistants here! My husband is writing a book and hardly sees daylight at the moment.

Is a drum mixer the same as the tub mixer you sent me the link for on Machine Mart? If so, that's the pricy one. I'll see what Ebay have.

Sue

 

[skier-hughes]

A drum mixer is a normal cement mixer.