Looking for information on staining or dyeing interior/exterior lime plasters. Specifically what works, how they affect and are effected by routine lime washing, scrubbing, and weathering. This is for a final coat using dark masonry sand on a 8000' desert dome. I know some Concrete dyes and stains can handle the Ph. And I recall ferrous sulfate is pretty toxic.
Any websites or experiences y'all can share?
Also I have a big box of deer/elk hair. Should I add em?
Have you already applied the plaster? I prefer pigmenting the plaster rather than staining after the fact.
IMO ferrous sulfate isn't any more toxic than the lime in the plaster. It is an irritant - but not as bad as lime. It turns concrete and lime plasters a rust/orange color. However, initially it will turn it a greenish color before finally turning orange. It will also turn wood to a grey similar to weathered wood.
I have used pigments from earthpigments.com Their product descriptions say if the pigment is lime/cement stable.
I've also used different color clays to pigment lime plaster with good results. For lighter colors you might use a couple cups of clay per 5 gallons of plaster.
Usually, I mix small color/mix tests and apply them to scrap drywall or backer board. Be sure to let it cure at least a day before judging the color.
I don't know about using the deer hair. Put it is a test or two and see how it goes. I like to put my test panels out in the elements and subject them to other abuse - you can tell a lot that way.
I like to add pigment to the mix as well. I use Bioshield, but I have used paint pigment from the paint store as well.
Animal hair is generally added to the scratch and brown coats, but not to the color coat.
I really like lime washes because of the depth of color you can achieve with multiple colors. One of my favorite interior jobs was grey clay, then plain white lime plaster and azurite lime wash over the top, troweled to expose all three layers in a random sort of way.
The best advice was already given; make as many testers as you can. Additionally, use high quality materials and burnish like you stole it.
There is so much out there now, and most if it is pretty good info.
Testing can not be stressed enough and allowing them to "age and oxidize" if possible.
Full matrix coloration is the only way to go, as any "surface treatment" is subject to degradation.
Hair additives are more applicable to internal plasters than to external renders. Most Undulate like deer, elk, moose, have hollow hair that is insulative...yes...but very brittle. Hog hair is much more robust and seems to resist the alkalinity of lime much better...Again, experiment and share your results. Plant fiber is the over all best fiber as is additives like "rice soup" which is an ancient additive to lime and earth plasters. This is seldom (only a few of us have written of this method in English) is well known and documented but the formulations are handed down to orally, and any in depth studies are mainly in Chinese.
I could continue for pages on the many amalgamations of lime - earth plasters, and there pigmenting, but a good Googling will get most folks what they need.