Preparing the GF ceiling

Ground floor ceiling being prepped ready for plastering.

Chalk plaster

We're trying out a new plaster today - it is a chalk - lime mix with polypropylene fibres.

It is a pre-mixed product by Fibrelime.  It comes to site in tubs.

After it has been knocked up with a splash of water.

It works best when a fairly tight coat of approx 2-3mm.  When we tried it thicker than this it was difficult to get it flat, as it was difficult to rule.

A finished wall (and the right hand side of the ceiling - the other side is lime-sand mix).

The fibrelime gives a really nice silky finish - probably the nicest finish of all the mixes we have tried to date.  We are going to stick with this mix for the foreseeable future!

Progress

The bathroom plastered and limewashing underway.

Bedroom 3 also plastered and clay wall limewashed, with window lining also limewashed.

Limewash

Next up is limewash.  This is a pre-mixed version bought from Mike Wye.

This is what it looks like when mixed up.  Like  the casein paint when applied it becomes translucent and looks awful until it dries and becomes opaque.  It is built up in a number of coats, we are doing about 4.  Because it is translucent when applied it makes it very difficult to see where you have been.  It can be used on plaster and on wood.  On the lime plaster it becomes part of the lime plaster, and any cracks completely disappear.  We wet the plaster down before the first coat if it is dry but the limewash can be applied as soon as the plaster can take a brush.  We have not been wetting it down between coats as the water tends to just run off when we have tried.

We are going to mix the next limewash up on site.  There are various ways this can be done, with either lime putty, hydrated lime or hydraulic lime.  We are going to try hydrated lime mixed 1:2 with water.  In the top coat we are adding some raw linseed oil to stop the surface from being dusty.  We are bought 100% linseed oil, as some makes have other additives in them.  We'll let you know how we get on!

Casein paint

We have started trying out alternative paints.  First up is casein paint.  This is a highly breathable paint free from VOCs, acrylics, oils and solvents.  It comes as a powder which you mix with water.  Two coats are recommended and it is more expensive than limewash per coat but less expensive than earthborne clay paint.  The paint produced a nice mat finish but it did not fill into the cracks in the lime plaster, but sat on top similar to a more conventional paint.

Clay plaster

We have used clay finish plaster on both the clay plaster on the straw walls and on the magnesium board.  This clay is made and sold by Womersleys.  When applied it tends to roll off the trowel, it can be applied thicker than the lime plasterers we tried and so on the magnesium board went over the beads better.  It was better when mixed slightly drier on the magnesium board, but the magnesium board still tended to make the plaster dry very unevenly.

It took longer to get a good finish, and it was critical to catch it just right otherwise the surface tended to become dusty and not be bound properly.  It did produce a nice finish which did not crack or shrink back.  Clay plaster does not have a 'set' like lime, it is either wet or dry and it can forever be changed from one state to the other.  This does make it more difficult to decorate, as when you work in the lime wash or paint it tends to absorb into the plaster and make it live again, rucking up the surface.  One suggestion we are going to give a go is applying the limewash with a trowel - could be interesting!

Tadelakt plaster

In the shower room we are using Tadelakt plaster to all walls and ceiling, including the walls in the shower instead of wall tiling.  Tadelakt is a waterproof lime based plaster which comes from Morocco.  The magnesium board has been primed with Magnaprime and a base coat of Limewall applied.  Following this two coats of the tadelakt are applied.

Once this has dried a polishing soap is brushed on.

This soap is made with tree oils, especially olive oils.

The surface is then polished with a special stone to produce a shine.

A second application of the soap is polished up with a lambswool bonnet.

The shower after the first application of polish and burnishing with the stone.

More plastering - master bedroom

Site mixed lime putty / kiln dried sand applied on the studwork partitions.

Undercoat of clay applied to the straw walls.