Hydrated lime plaster and limework where limework isn't common

If you are building from earh/cob in an area that is remote or limework is uncommon, lime plastering can be a challenge. I live and built an earthbag/cob home in the southeastern USA. There is very little limework in this region and no local vendors who sell it. I learned how to lime plaster with books and the internet, but sourcing materials was difficult. Here ate a few things I have learned and I hope they can help.

Hydrated lime can be used successfully to make plaster and limewash though it is considered inferior or entirely unsuitable by the experts. I could not afford to import proper lime from abroad or ship it from the northeastern usa where limework is more common. You can generally find hydrated lime at agricultural suppliers (the sort that sell fertilizer and chemicals). It does absorb moisture so make sure to check the bags haven't hardened up before you buy them. The bags are 50 lbs and cost about 13 dollars near me. Most books have lime:sand ratios made for slaked (wetted) lime so using dry hydrated lime will require some experimentation.

I like to use a battery powered plaster mixer to mix the lime and fiber into the water before adding the sand. This makes sure the lime mixes all the way without leaving lumps. I use cut off 55 galon plastic drums for mixing as they are cheap and tough. I use cellulose insulation as fiber because it is cheap, has fine fiber size and requires less prep than other options. A mix I like to use for finishing consists of  
1 bag of hydrated lime, 5 gallons of sand and 2 gallons of fiber. I use this as the final coat and whitewash it after.

I like lime but ita can be a hassle to work with. It is caustic and messy, not to mention it costs money. For this reason I only use it for a finish coat and limewash. I make a clay plaster to form corners and edges as well as even out walls. There is no sense in using lime when you don't have to. I add a little lime to this clay plaster to make it more sticky and to cure harder/ add water resistance. It consists of 15 gallons of clay dirt, 2 gallons of lime and 5 gallons of fiber. I add dish soap to this mix as well as the lime mix. My theory is that the dish soap acts as a wetting agent and it makes both mixes more creamy and workable. I think I may use this mix for my floors as well.

Lime plaster surfaces need to be wet down before, during and after work to slow the curing process and prevent cracking. I am in an off grid situation so I wired a diagram pump mounted on a blue barrel so it could take dewalt batteries charged by my solar panels. This enables me to add soap to my spray water and is much easier than a hand pump sprayer. I use a stainless steel concrete finishing trowel for big areas and a Japanese square trowel for tight spaces. I use regular paintbrushes to apply limewash and polish ridges or corners.

If you have an exterior area you want to quickly protect or are going for a more rustic look, consider a harl coat of lime. Harling was used in rainy climates like northern England and Scotland. It dries very rapidly and is an easy surface for wildlife to climb and rest on if that's your thing. I make a very sandy lime plaster mix and then add water till it has a liquid consistency. To apply you flick it on the wall with some force. I was using an old brick trowel with the front half snapped off. Later I bought a true harling trowel offline which is way better. Harling sticks to cob walls well and allows a good surface foe later trowled plasters.