I built a rocket mass heater in November-December 2014, and it has done well for us for two seasons.
However, it sheds clay and sand. I used a local red clay (1 part) and finer grade yellow sand (2 - 3 parts) with straw for the finish layer on the bench.
I'm trying to figure out a good way to make sure that the bench does not shed any more clay and sand.
I've thought of linseed oil (I have some with chemicals in it that I'd prefer NOT to use.
I've also thought of a hydrated lime + very fine sand mixture.
Any suggestions for me, including links to products? Any recipes to share?
I tried searching forums on here, and must be a total ninny at searching.
Any help appreciated!
Satamax Antone wrote:I think any plaster or render will shed if used as a bench, no mater what. Even concrete would. Tho, a lime plaster might shed far less.
Two ideas come to mind, tadelakt, may be an option.
Or waxing the surface.
Thank you Satamax!
I found a source of local granite powder.
Have you, or anyone else, used tadelakt in actual applications? If so, is there a particular type of lime that I should get? A local quarry has Calcium dominant lime, as well as Magnesium dominated lime. There's also the traditional 50 lb. bag of hydrated lime. Any suggestions would be helpful!
Does anyone have a source of pigmentation? Can you make your own? I'm looking for a beige color.
Careful, it's not an easy job. The mixture of lime and charge are rather stringent. When you need to polish the surface with the pebble, you have to do it right now, not half an hour later. I've seen him working in a hammam in my village, waking up in the middle of the night, to polish with the pebble.
thomas rubino wrote:Adam; Here is where I purchased pigment for my cob. http://www.earthpigments.com/ All natural, heat resistant below apx 200 F Very nice product ! You can also get red ,black and yellow dye for concrete at a home depot type store.
In terms of Tadelakt, is the process to do:
1. A base coat of plain white tadelakt;
2. A finish coat of pigmented tadelakt; and
3. A final coat of black soap?
If I'm applying to a cob rocket mass heater, do I still need the base coat?
Which coats do I need to polish? Just the finish coat and the black soap coat?
Also, what would the ratios be in each coat? I believe that 10% pigment to lime ratio is used by weight. Is that right?
Any input appreciated! I've been scouring the internet trying to figure this out.