Friday 14 February 2014
It may be Valentine's day, but work goes on as usual. We thought we'd put in a post about the technical stuff, for anyone out there who is interested, and to help us remember ...! We have read various books on the right mixes to use, and each one has its opinion. This is what is working for us. It has stayed on so far - and survived quite a significant 'quake, but in a year or two we'll be in a better position to know for sure.
First coat: Extra sticky and squished hard into the bale surface. 1 part Lime Putty (obtained here in bags at every stone yard, ready for use) to 2 parts Sharp Sand. Quite a firm mix with water. Best applied with a wooden float apparently, but we can't get them here - should not be 'polished' with a metal float, apply rough, then sponge with water when nearly going off. (Anything from two days to a few hours, depending on temperature and humidity).
Filler: We use this over the first coat. Where the plaster has been pushed well into the bales, there are significant dips between courses or in stuffed gaps. By plastering first we expose these dips, and get a good covering for weather protection, then we can take our time to find and fill indents and level up corners, etc. Use same 1:2 mix of lime and sand, a little wetter. Half fill a bucket then add handfuls of chopped straw stirred in by hand like mixing flour into eggs until the consistency can be formed into a ball in the hand - see photos below:
Allow filler to dry, then apply second coat. No need to sponge the filler as the straw pieces make a good key.
Second coat: One part Lime Putty to three parts Sharp Sand, add water to a spreadable consistency, not too wet. Add half a part of cut straw in handfuls as the mix is mixing. Apply to wall. Sponge when nearly gone off.
Third coat: Same as the second. Then apply ideally three coats of limewash (top coat optionally with pigment of your choice added). Limewash is lime putty mixed with water to the consistency of milk, slopped on with a paintbrush. Take great care of your eyes.
It may be Valentine's day, but work goes on as usual. We thought we'd put in a post about the technical stuff, for anyone out there who is interested, and to help us remember ...! We have read various books on the right mixes to use, and each one has its opinion. This is what is working for us. It has stayed on so far - and survived quite a significant 'quake, but in a year or two we'll be in a better position to know for sure.
First coat: Extra sticky and squished hard into the bale surface. 1 part Lime Putty (obtained here in bags at every stone yard, ready for use) to 2 parts Sharp Sand. Quite a firm mix with water. Best applied with a wooden float apparently, but we can't get them here - should not be 'polished' with a metal float, apply rough, then sponge with water when nearly going off. (Anything from two days to a few hours, depending on temperature and humidity).
Filler: We use this over the first coat. Where the plaster has been pushed well into the bales, there are significant dips between courses or in stuffed gaps. By plastering first we expose these dips, and get a good covering for weather protection, then we can take our time to find and fill indents and level up corners, etc. Use same 1:2 mix of lime and sand, a little wetter. Half fill a bucket then add handfuls of chopped straw stirred in by hand like mixing flour into eggs until the consistency can be formed into a ball in the hand - see photos below:
Bucket of mixed plaster - 1:2 lime to sand
A handful of straw chopped in a metal bin using a strimmer, part shredded, with some remaining long pieces - long pieces can be pulled out. This makes a good sticky filler, as the fibres are small, so it is good for shallow indents, smoothing corners or topping up an indent.
A handful of straw chopped by hand with a knife - makes a more bulky filler, better in deep gaps, but less good for making a smooth join with surrounding plaster
The straw is stirred into the plaster by hand (rubber gloves essential as lime is very drying for the skin. Do not get it in eyes - wash immediately in running water). Keep stirring in until the mix gets difficult to manipulate
A good ball of straw filler - nice and firm. Work in the hand like a snowball to bring the lime to the surface, then splat onto the wall and rub in firmly by hand.
Allow filler to dry, then apply second coat. No need to sponge the filler as the straw pieces make a good key.
Second coat: One part Lime Putty to three parts Sharp Sand, add water to a spreadable consistency, not too wet. Add half a part of cut straw in handfuls as the mix is mixing. Apply to wall. Sponge when nearly gone off.
Third coat: Same as the second. Then apply ideally three coats of limewash (top coat optionally with pigment of your choice added). Limewash is lime putty mixed with water to the consistency of milk, slopped on with a paintbrush. Take great care of your eyes.
No comments:
Post a Comment