Hessian Roll sheeting helps to protect lime mortars from rain, sun and drying winds. In combination with tarpaulins they can also give frost protection.
Damping & curing
Hessian gives an extra control point in the curing of lime mortar, and lime renders. Dampening down hessian when in direct sun light, or strong winds will allow the lime mortar/render to cure more naturally, do this whenever the hessian is drying. When expecting slightly colder weather (do not apply when below 5 degrees, or expecting frosts). Doubling the hessian up, using with a tarp will give a little extra thermal protection.
Once you have finished leave the hessian in place for as long as is required.