If you have been in Spain for even just a short time, and have needed to do some work on your property, then you will no doubt have heard of Yeso.  Yeso is a substance which is very versatile in experienced hands, and downright frustrating in the hands of a novice.  I speak with some authority on this subject having once been a 'Yeso Virgin'.

Yeso is really a plaster, but not plaster as we know it, in the UK.  The big difference between the plaster that we use in he UK and Yeso, is that plaster in the UK is lime based and Yeso is gypsum based, which sets very quickly when added to water.

Gypsum in its natural form

I have come across 6 types of yeso in my travels, and I will attempt to describe them although I am not fully conversant with their uses, I will be asking my builder this weekend to elaborate.

Yeso is not just plaster it has many other uses, and techniques, once you get passed the yeso bucket stage you will understand what I mean.

• When mixing yeso it is favourable to only mix small quantities especially when using the fast setting types, unless of course you favour yeso buckets. 
• Always add the yeso to the water in small quantities, mixing well with each addition.
• Wherever possible wear a mask when handling yeso.
• If using a flicking technique goggles are essential as it really does hurt if you get it in your eyes.
• Plan where you are going to use the yeso before you mix it
• Have all the tools that you will need to hand before you start.
• Sometimes it is necessary to wet some surfaces prior to application of yeso, as it helps it to adhere and stops it drying out too quickly
• Always have a bucket of water to hand as it is useful for smoothing out the yeso.

I now know how to use yeso but it has been by a process of trial and error.  I couple of good friends showed me the technique of flicking yeso and that was an experience which was assisted with a few bottles of beer, this is a very messy technique where you make a mix of quite runny contralado, in a reasonable quantity and hand flick this at the walls of a cave which has never been treated before.  The flicking technique I believe is unique to the individual, mine seemed to work by scooping this yeso, which was the consistency of double cream, into a cupped hand and moving the hand very quickly towards the surface you wish to cover whilst opening your hand before impact.  This allows the yeso to splatter the wall.  This technique is used to form a base coat and seal the rock, allowing further coats to be applied by hand or with a float.

Painting with a dilute solution of yeso can also be very effective, and you can cover quite an area before the yeso starts to go off.  Again the mix is of contralado and mixture needs to be more or less the consistency of thinned emulsion paint.  Technique is the same you would use when painting but the trick is not to overpaint.  I usually use this technique over virgin rock or areas which need a touch up or smoothing.

I have used yeso to sculpt arches and doorways where there is exposed rock.  I had a window removed between my new kitchen and the old pantry, which formed a doorway, this was very rough with bits of rock sticking out, so I mixed batch after batch of contralado and smoothed this over the exposed rocks, layer after layer with my hands, until I had managed to sculpt a pretty decent doorway which tied in the new extension and the older cave room.

Rapido is a bit of a challenge and you cannot hang around with it or it will set whilst your back in turned.  We have used rapido to fix  the new windows and doors in place, to secure electrical conduit, prior to the finishing plaster.

Contralado and rapido are very good for moulding either by hand or in a mould.  Moulds can be bought from hobby shops and online.  You could, if you wish, make moulds like architraves an ceiling mouldings

 Another pretty neat idea, and more especially if you have kids, is the footprint plaque.  I would advise using cling film so their delicate skin does not have direct contact with the yeso, but it is a nice memento to hang on the wall.

Yeso can be your friend and as you progress you will realise just how much of a friend it can be