japanese trowels | Inspirational Village

Final Lime Plaster

06 Nov 2012 5 Comments

by inspirationalvillage in Natural Building Tags: cob sculpture, colour pigments, earthen plaster, japanese trowels, lime plaster, natural building

Back in May (2011) we decided to get going on the final lime plaster of the outside of the house before the business of summer cob building took over. Lime prefers to have cooler temperatures in which to dry, and requires much more attention to the timing of the drying process for a result of eveness of colour and trowel lines. Much like the process of applying the cayolin clay plaster on the inside, lime needs to be troweled on continually until a whole section can be completed, otherwise an apparent line will be visible where the plaster dried too fast, or where troweling stopped. There are techniques to make these lines look less visible if whole big sections are difficult to complete in one go at it. We added a beveled line that undulates around the house, dividing the wall into smaller sections and providing a place for us to stop. That way we were able to plaster only the top section, and then only the bottom, and have the line of plaster meet under the bevel and so be hidden.

moving along in a team of three

Working with three people who are competent with the job is important. Fixing spots as you go, running out of plaster when you need it, and being too late for the sponging part of plastering is stressful. So is having the sun come out unexpectedly and not being able to stop to find a way of shading the work space. Likewise, having lunch, snacks, and drinks being made available while working is a huge bonus in making lime plastering a smooth and fun thing to do.

getting those mixing muscles flexing

The right tools are also necessary. We used Japanese trowels, hawks (easy to make-plywood board with a handle on one side), just like with the interior plaster, and mixed the plaster in 5 gallon buckets and then in a large tub for uniform colour and consistency. A powerful drill with a paint mixer attached, measuring spoons and cups (depending on colour pigment used), a spatula, and big scooper are helpful to have on hand. Ladders or scaffolding should be close by for high parts.

The ingredients are simple- hydrated lime, stucco sand, water, and colour pigment. We soaked the lime in a big barrel a few weeks in advance. We also did many colour samples using a one litre mix, adding pigments in increments of tablespoons to get an array of shades and colour blends. We have many beautiful arbutus trees framing the house, and we wanted to make a colour that brought out a reflection of the deep red/orange/brown that we see in the twisting branches. We also thought that such a colour would bring out the vibrant yellow of the yellow cedar window frames. Red pigment, however, has pink tendencies, and so we ended up using ten tablespoons of red in a one litre mix, plus five tablespoons of chestnut brown. Multiplying that up to 4 gallons in a bucket, and we were deep into a large quantity of pigment. We ordered what we thought would be enough for the whole house, based on calculations for the area covered per bucket on the inside, but discovered partway through the job that we had only enough for just over half the house. We spent way more money on colour pigment than we ever expected, but we were committed to the colour. Lesson #1: estimating for natural plasters is difficult, and calculating for colour pigments is even more complicated. Lesson #2: find a good source of affordable, bulk colour pigments. Because we were pushing to get this job done while the weather was still cool, we just walked in to a concrete supply store and bought mortar pigments that come in small bags. When we discovered just how much we would need, we didn’t want to take the time to find a different source because different pigments have different colour shades. We would have needed to do the colour sampling all over again. By the time we ran out and needed more though, I was very much wishing that we had. However, in the end we spent about $800 in the final outside layer (incl. lime and sand), and compared to other forms of siding or paint, we have a beautiful plaster that soaks in to the landscape, accentuates the curves of the bales and the coziness of the forest, for probably less money in the end.

The very first thing we had to do, before any of the plaster went on, was to add the sculptural elements to the rough coat. Elemental it was, too – the aspect of the house is situated very close to the four directions, and we wanted to acknowledge the directions and the elements on each side of the house.

south sun

We sculpted a large sun on the south side for fire, and a water lily on the west side for water. My mom got to work on sculpting a tree on the north side for earth, and I placed two dragonflies on the east wall under the light that shines beside the front door for air. Our beveled relief line that undulates through the middle of the wall flows through each of the elemental sculptures and adds a subtle shadow line. The sculptures were made using the same mix as was used for the brown coat of the walls- 1 part clay, 2 parts sand, and 1 part chopped straw. Fine sand and clay sifted free of rocks makes the plaster easier to shape. We also wet down the wall and spread clay slip over the area to help with adhesion.

mixing lime, sand, and pigment

Lime plaster: 1 part lime, 3 parts sand. For us, this meant 5 litres lime and 15 litres sand. That is what we could mix in one 5 gallon bucket. Spin it together with the mixer, and add colour pigment, mixing it in with a small amount of water. Then we turned three buckets into the big tub and mixed them all together. We worked out of this tub until we got low, then had our extra person work on mixing up more.

Before we started on the walls, I went around and plastered the sculptural areas first, thinking that it would make plastering the walls faster to do rather than having to do the intricacies at the same time as keeping ahead of the drying plaster. Two were done in white, and two were done as the same colour as the walls. What I discovered was this was not as straight forwards when it came time to do the walls. Red pigment, as well as splatter from the rough coat of clay as it was being sprayed with water, got all over the finished sculpture and needed cleaning and touching up afterwards. Also, it was hard to sponge the plaster without touching the already plastered areas, which made the transitions between the two look smudgy. From a distance, it is not a big deal at all, and since this is the outside, we usually look at it from a certain distance. So I recommend doing it all at the same time- just consider simple sculpture lines and expect to be slowed down considerably when plastering these areas. Small tools are essential, as well as the all useful yogurt lid with the rim cut off.

sponging- making the finish texture smooth and uniform

The sponging part of the process comes when the plaster is tacky enough to leave finger prints but dry enough that no plaster comes off onto the fingers. It can be a very precise moment, depending on the weather and how fast the plaster may be drying. A damp sponge is simply moved around in circles to remove the troweling marks and give a smooth, uniform look to the whole wall. Sponging too soon will pull at the plaster too much, and sponging too late means that the sponge needs to be wetter and a stronger motion is needed to smooth out the trowel marks. A well troweled wall, however, won’t have very many marks to be eliminated. We noticed that sponging on a too dry wall caused a variation in the colour pigment, making it a lighter shade, just like when we sponged near an already plastered spot and brushed up against it.

final plaster layer is about 1/4 inch thick

Our process went pretty smoothly. Colin and I mixed what we needed for the day and did the troweling with a friend who pre-sprayed the wall sections ahead of us with water, sponged along behind us when the plaster was ready, and helped remix some of the plaster from the bottoms of the buckets when it began to dry out too much. Getting familiar with the perfect consistency is learned simply through using the plaster, and noticing when it is too dry and difficult to spread or too wet and sliding off the trowel.

the art of troweling is challenged when ladders and awkward spaces need to be reached

The motion of getting it from hawk to trowel to wall is also a practiced motion that comes with repetition. Generally, I would make lots of little overlapping rainbow swipes over a one foot square area, and then smooth the whole area down in larger swipes right away, and move on. No putzing allowed! Get it on, flatten it out, and move on. Plastering a whole house gives lots of opportunity for repetitive motion learning… start with the most hidden space and do the area around the front door last.

dragonflies at the front entrance

There are many details and considerations with lime plaster, and it is helpful if you have experience with some other form of earthen plastering, or if someone who does can give a hands-on lesson. Again, we had the direction of Tracy Calvert, who has been building naturally since the 1980’s and has specialized in earthen plasters. She has led many workshops and believes that skills of natural building are to be available for anyone willing to learn, like the traditional practices passed down from cultures around the world that enable the reality of shelter for everyone in a community and not only for the wealthy.

north tree

west water lily

The Earthen Floor

21 Jan 2012 2 Comments

by inspirationalvillage in Natural Building Tags: burnishing, clay slip, cob subfloor, earthen floor, japanese trowels, linseed oil, natural building, wood finish

burnishing the floor at the "leathery" stage

The south room floor is the one spot in the house where we continued with our plan for laying out an earthen floor, in hopes of capturing the heat of the southern sun that streams in during the winter months. The rest of the house, which was originally intended to be an earthen floor, became cork flooring due to some time pressures and uncertainties regarding the success of the earthen floor process. (See my previous post titled The Layers Beneath Our Feet for a total description of the floor.) We found lots of information, tips, recipes, ideas, things that didn’t work, and things that did from a variety of resources, some of which contradicted each other, or were from climates very different from ours, or which used materials that were unavailable or too expensive for us.

lots of considerations and discussions

Figuring out what to do was challenging. Tracy joined us again for the experience of mixing and laying our earthen floor, and we are grateful to her for sharing her observations and experiences of working with natural plasters. (Tracy is our natural plaster and straw bale teacher.) We wanted to use what we had and we felt most comfortable with techniques that were familiar to us from the wall plastering that we had just completed. Cracking seemed to be the biggest common result, and one that is difficult to fix without a very messy look. We heard of filling the cracks with different coloured plaster to create a marbled look, but we never found a source of a good example of this method. A certain amount of experimentation, intuition, applied knowledge and trust was going to be needed. This was the point at which we were grateful that it was now only a small 200 square feet that we had to do.

clay slip

We decided to follow (loosely) a set of well laid out steps and recipe ideas from Anne and Gord Bailey, of Eco-Sense on Vancouver Island, ecosenseliving.wordpress.com. We adapted the recipe to what we had available, which was screened clay mixed into a slurry, red clay mixed into a slurry, stucco sand, horse manure, straw, and some red pigment. We started by laying down a cob sub floor at a depth of 3/4 inch using a mix that resembled our second coat of wall plaster. When that was dry we mixed up the top layer in 5 gallon buckets, then tried a technique we saw on the internet of laying burlap all over the floor area, wetting it and slopping clay slip as a binder then troweling on the 1/4 inch thick top layer. I am breezing through the details here because it didn’t work. We thought that the burlap would help reduce the shrinkage factor of the clay that leads to cracking, but it didn’t at all, and it also prevented the top layer from bonding well to the layer below the burlap. We think it dried too fast, the layer was not wet enough, the burlap wasn’t soaked well enough, or there was just too much clay content in the mix to begin with.

troweling on the top layer

So we ripped it up! Just chipped through to the burlap and pulled, and it lifted too easily. We crumbled it back into the buckets, then worked out a few new ratios of higher sand and straw contents. We laid out some sample areas and let them dry to see how the cracking went, and decided to make the mix with 4 parts sand, and one part clay slip. Because of the remixing, it is hard to say what the quantities were for the various other ingredients.

sifted manure

Fibers (manure and straw) were around 1 1/2 parts, and water content was based entirely on feel and how the mixer spun. Not too wet, not too runny.

This time we left out the burlap. We also poured buckets of water all over the floor the night before to keep the cob subfloor cool and to prevent it from sucking moisture out of the layer we troweled on top. We hung blankets over the windows to try to keep the summer sun from hitting it right away. It took a whole day of two people troweling on hands and knees to get our 200 square feet covered once again, then while it slowly dried we lay planks across the floor so we could burnish it, giving it a polished look while compressing it more, and hoping to prevent too many cracks. The outcome was 90% better than the first try. We had a few thin cracks, mostly where it dried the fastest, and no lifting.

The recommended method for fixing the cracks was to use some left over plaster.

the worst of the cracking after the second try

We dried it out, crushed it, screened it through window screen, then sprinkled it into the cracks while wetting the area with a mister and troweling it smooth as best as we could. There was a bit of texture difference for sure, but we decided that it was a natural floor overall and a bit of texture was fine! Then we began with the oiling and waxing. This was another reason we were glad to have done only a small portion of our floor- we brushed on 3 coats of boiled linseed oil, and two coats of Land Ark oil, which contains beeswax, tong oil, linseed oil, citrus extract, and pine rosin. Land Ark is made with only natural, non-altered ingredients from sustainable resources, without chemical processing, bleaching, or harmful additives.

oiling with linseed oil

We have also used it on the timber frame,door and window trims, the baseboards, and the ceiling boards. It actually feels great to get on my skin, and I love the smell of it as I have done much of the staining. For more info on a great product- www.landarkwoodfinish.com. The cost of this oil runs at about $85 a gallon, so we were hesitant about what it may have cost in oil to finish a larger area of floor, since we didn’t know how many coats the floor would take. We read that it could be anywhere between 3 and 10, with at least 2 being the straight linseed oil. Then we waxed the floor, using another natural wax from Land Ark, and then buffing it hard with a buffer. The golden flecks of straw suddenly jumped out, and the places of various texture and colour deepened and settled in.

The best part of the finishing of the floor was not anything that we read or heard about in all of our earthen floor research, and so here I would like to add it in as a recommended part of laying an earthen floor. Don’t move in any furniture, but set up the stereo. Lite some candles, build an altar, and invite as many people as can dance on your floor. Put on a rocking playlist, strip off the socks and stomp, swirl, boogie, laugh, and send all that energy of celebration, gratitude, and joy through the soles of your feet into the hard work and beauty of the earth. That’s what we did, quite unexpectedly. We felt warmly supported by our friends, and happy to finally be able to open our space for gathering together and sharing what we have.

Final Plastering

08 Sep 2011 7 Comments

by inspirationalvillage in Natural Building Tags: cob sculpture, cob walls, earthen plaster, japanese trowels, kaolin clay, natural building

This summer, we have finally completed the last layers of the inside wrap of the house, including all the flooring and the final coat of clay based plaster on all the walls. This last layer of clay plaster was much more particular in recipe and in application than the rest of the rough layers, and calls for it’s own chapter in explanation. (I have already outlined the procedure for the rough coats of plaster in a previous posting, Natural Plaster.) I would like to express my understanding of our process in openness to the many other recipes, methods, and materials that have been used with success throughout time and in many different places.

My experience is limited to our one house here on the west coast of Canada. However, we have also been guided by our friend Tracy Calvert who has compiled her own knowledge and experience and has willingly and generously passed it on to us throughout our journey. The ingredients in the recipe that we used are kaolin clay, stucco sand, fine straw, whiting (calcium carbonate), paper pulp, rice flour, and a small amount of borax and white glue. The Kaolin clay is a fine powdered porcelin clay that was purchased at a pottery supply store, as well as the whiting, which is basically a chalk filler.

We used finely chopped straw left over from baling, but we also used an alternate fiber material of bulrush down, the fluffy insides of cattail heads harvested before they turn inside out. The sand is just fine washed stucco sand, and the rice flour is mixed with hot water and made into a glutinous paste. We soaked newspaper overnight and then pulped it up with our paddle mixer, which we used to make the plaster in buckets. Ratios are as follows : 6 parts sand, 4 parts clay powder, 2 parts whiting, 1 part straw, and 2 parts paper pulp, 3/4 part rice flour mix, a handful of borax, and two or three glugs of glue. One part for us was a 1 1/4 litre bucket. First we dry mixed in 5 gallon buckets the sand, clay, whiting and straw, then added the paper pulp and enough water to make the mix spin easily but stiffly.

Because we were going to wait to plaster the next day, we left the mixes at this stage overnight. When we were ready to plaster, we added the rest of the ingredients and any colour pigment we were using, then compiled three of the buckets into a big tub and mixed them thoroughly together. This helps with consistency of ingredient quantities as well as getting the bottoms of the buckets mixed in well. For colour pigments, we did some test samples using tablespoons of pigment to 1 litre of mix, then allowed the samples to dry to the finish shade. We then multiplied the tablespoon quantity for the amount of litres in the 5 gallon buckets (some estimating was definitely relied upon) and added that amount of tablespoons of pigment per bucket. Finally we were ready to put it on the walls! We sprayed the walls with water to help bond the two layers together, then considered how to plaster each section without stopping or ending up with long edges of plaster that are left a little too long and begin to dry out. Unlike the regular clay plaster, there is only so much re-wetting that the plaster can take before it is too difficult to smoothly work new plaster up to it without leaving lines or smudgy areas. This sensitivity to time makes considerations of temperature and air flow quite important, and usually requires two or three people working together for smooth going. We had two of us plastering, and one person in charge of mixing up new mixes, moving ladders, bringing coffee, keeping the music flowing, and generally making it possible for us to keep working our lines until a section is done. We spent almost five days in total plastering the whole inside of our house, which worked out to be about 1200 square feet of wall and used approx. 27 buckets of mix (one mix being one recipe.) We used japanese trowels, bought through the internet, and homemade hawks (rectangles of plywood with a handle on one side), as well as a few smaller tools for tight corners and edges, and yogurt lids with the rim cut off for shaping curves. Generally, we covered an area with overlapping rainbow swipes, then flattened them all down in larger sweeping motions. We plastered over drywall as well, which we had prepared with glue and sand to provide a grippy surface.

All the kickboards and window and door trim were put in place first so that the final plaster came to meet the trim and seal any spaces. We also tiled the sills of some of the windows before hand. At a certain time of dryness, we went over the whole wall with a damp sponge to blur any lines and troweling marks, then at another certain point in dryness we burnished the whole wall with a yogurt lid. This brings up the clay and pushes in any sand, and gives the plaster a certain polish that makes it more durable and smooth.

We are so happy about our earthen walls, from the clay slip through the rough coats and finally plastered with the finished layer. I began this house knowing absolutely nothing about natural plaster, and although it took lots of work and patience, it provided a full scope of learning the art of earthen plaster. There is always more to learn, and I look forwards to continuing on and developing my methods and skills throughout the second half of the house. I am so very grateful to Tracy for leading us on this path and providing support as well as space for us to take it on and call it our own. The passing on of this type of skill is important to her as we share and expand our self- sustaining abilities for building beautiful and healthy homes.