Super Smooth

Welcome, Dan!
I'm currently in the process of applying earth plasters in a small straw bale house I've built (with the help of many amazing friends). I want the finish to be truly splendiferous and begging to be touched. Truly going for sparkle-fairy-pony-pretty look in some places. I'm almost to that part and am wondering if it is possible to get something with tactile appeal from an aliz or if I need to actually put on a thin coat of finish plaster. Also, I've seen instructions for putting mica directly ON the finished wall with a flour paste instead of incorporating it into the finish plaster and wonder what you think of that.

Hi Kim...You can achieve a very smooth, almost sensuous to touch, finish by troweling on a finish plaster but working it pretty hard with a steel trowel. We make a finish plaster out of powdered clay and fine-grained silica sand, in a ratio of about 1 part clay to two parts sand. You can substitute powdered silica sand for a really smooth finish. The secret, though, in my experience is that the results come from trowel work. You need to work the finish coat, smoothing it out pretty quickly after you apply it...so don't get too far ahead of yourself, or have someone following up a person putting the finish plaster on the wall. If you make the mix a little wetter, it gives you a bit more time to work it. You can also burnish the finish plaster with a lid to a yoghurt container, describing circles with the lid.

That said, you can achieve the same results with an alis. That word, by the way, comes from alisandro, the Spanish name for the ladies who used to do the plaster work. We make alises with a 50:50 mix of powdered clay and fine-grained silica sand. Instead of adding water, we use powdered milk, diluted by 50%. In other words, add twice as much water as the recipe for preparing "drinkable" mild.

Be sure to experiment with mixes and techniques before you start working on a wall so you know what you are doing and can do a superb job on the finished wall. Keep in mind, too, that it takes a long time to really master finish coats. I still feel like I'm learning and I've been at it for a lot of year.

Hope this helps.

Dan

Thanks so much, Dan! Just want to make sure I have this right...the difference between a finish plaster and an alis is only in the liquid; both content and quantity? I use the diluted powdered milk and add more than I would for making a plaster, right? Also, what about the question of adding mica to a flour paste and applying it on a finished surface instead of adding to the finish plaster/alis? And IF you say I should put it directly into the plaster or alis how much would you recommend? I'm just about to do this to a beautiful vault designed by Kelly Lerner as my "bedwomb" and I want it to be fabulous!

Hi Kim:

The difference between a finish plaster and an alis is not only the liquid, alises are more liquid, but the ratio of clay to sand. An alis is typically a 1:1 mix. A finish plaster is 1 part clay to two parts sand...usually. I use powdered milk for both alises and finish plasters.

I have no experience adding mica to a flour paste and applying it on a finished surface. Interesting idea, but just don't know anything about it.

I add mica directly to alises and finish plasters. Remember to reduce the sand content proportionately. You can easily replace one fourth of the sand with mica. Again, Kim, experiment first to see what works best.

Dan

Sorry, misread the ratios! This is SOOOOOOOO helpful, Dan. I am going to give it a go and see how it comes out. I very much appreciate the opportunity to pick your brain.

Kim

Not sure if this helps, yet you can also burnish with "polishing stone" as when we do Tadelakt work. This makes almost any additional augmentation more robust...though this is a more "polished look," than just simply tactile. Also the addition of "plant fuzz" to a finish can make a very interesting finish technique as doe botanical impression work in a differ color slip.

That's great input, Jay; thank you. I've actually tried this and found that trying to burnish with a smooth stone left indentations in my plaster, I couldn't get it flat for the life of me. Maybe I did it too soon or the stone wasn't the right size? It was a really nice river rock that was smooth and fit perfectly in my hand. Should one use a polished stone instead? Did I press too hard??

Hi Kim,

Remember with burnishing techniques there is also the addition of lipids and waxes in the process quite often. The stone does need to be "glass smooth" and very hard, or you will get a matt finish. Some folks are successful with horn and hardwood burnishers...no success there for me yet. Japanese with use there many different style planes and dip them in water, sea weed, rice paste, blood, lipids (oils) etc.

Regards,

j

Just saw this today while clicking around the net:

Polished Tosa Shikkui