Tuesday, 1 March 2011

Handy hint that smells of mint

This really isn't the sort of weather to be doing work like that shown above - my fingers end up almost as cold as the little marble ones in the top picture, which is why I am distracting myself by talking about it rather than actually doing it.

You may remember the 2/3rds life-sized marble Venus that I promised to finish last summer. Well this is as far as I have got with it. I'm just so lazy, and it has been either too hot or too cold to work any harder - the 'Goldylocks' zone must have happened when I was on holiday.

When you are working on bits of marble as small as this, you end up chasing them around the work-bench unless you clamp then down to something heavy enough, and the smaller they get, the more likely they are to break. That finger is about twice as large as it will end up right now, so there is every possibility that it will disintegrate after I have spent a day working on it. Marble is so brittle that anything under about 6 inches cube has to be abraded rather than hit. It's bad enough with modern, diamond coated power tools - just think what it must have been like in the 18th century, when all they had was wet sand on a bow-string.

You can see the clay finger above it (modeled by my charming assistant) which is being used as a guide. The trouble with clay is that it shrinks and cracks when it gets old, so you have to keep it damp. Luckily, that hasn't been too difficult over the last couple of weeks - it's been more of a problem to stop it getting washed away.

Do you recognise the blue stuff in the lower photo? I'll give you a clue - it tastes and smells of mint. I use this stuff to take an impression of the cavity of missing marble (in this case, just above an ankle), then use the positive lump as a guide when cutting the piece that will fill in the break. You have to work quick with it, as it goes off in about 2 minutes. As it goes off, it starts by being slightly rubbery and flexible, which means that you can pull it out from the hole quite easily. Then it goes drier and harder over a period of time, BUT - and this is a big advantage - it does not shrink or change shape at all. It stays exactly the same size as it was when wet, so it is extremely accurate for tight joints.

Do you recognise it now? Ok, I'll tell you what it is called: 'Alginate'. It is made from seaweed (or similar organisms), and I bought it from a Bristol wholesale dental supplier.

Yes, it's the same stuff that they cram into your mouth to take an impression of your teeth (if you are lucky enough to still have any) from which to make a 100% accurate plaster positive.

When I have finally finished this little job, I will be taking it back to the customer, and this process is known as The Transit of Venus. (sorry)


  1. I'm going to make a trip down to the Isle of Portland this week, to select some stone from the famous quarries there, and I'm going to take a camera. If you are interested in the glamorous world of stone and stone-carvers, then that post will be extremely exciting for you. If not, then it will bore the shit out of you.

  2. Tom you are never boring. Is marble a good suface for a kitchen counter top? Granite is all the rage over here but I do not like it. I have a dear friend who wants marble. I realize you are an artist and not a counter top installer but what do you think?

  3. I was supposed to be working outside today... far too cold!!

  4. giving venus the finger eh?

    warm up here!

  5. I saw somebody on TV last night using that dental stuff to repair a bit on an old frame - worked very well.

  6. Yes, I saw that TV programme too. He had bought 10 antique mirror frames from France. He did a fair job with the mouldings but then ruined them (in my opinion) by painting them white (over the gold) and marketing them as shabby chic. Interesting stuff though, that Alginate.

  7. Mrble is fine for a work surface, Olive, but bear in mind that it stains very easily, and it is softer than granite, so will scar easily too if you use a knife on it. It also bruises quite deeply if you drop a heavy item on to it. You will need to seal it with a substance made from ghastly chemicals ('Stainstop' made by Fiddes is one), and you will have to treat it with kid gloves if it is pure white, or grey-veined white.

    Alginate is absolutely no substitute for real Stucco, so they guy would have to be very clever to do as good a job on a picture moulding.

    Up where, John?

  8. :) Chortling at you and John! Chortle chortle!