Hi, first time posting to these forums!
I was wondering, if I didn't have access to straw or manure when mixing cobb or natural plaster, could I mix paper pulp and/or cotton pulp with the cobb mix (i.e. sand clay water)? Because I think it would be cheaper than having a load of straw bales shipped and building a facility to keep them dry. A mix could be: paper pulp, shredded cottons/burlap, sand, clay and water... would that work?
Because you are only specking about Plaster and not the main cob walls, your suggested alternatives would be fine.
In fact, many of the plasters call for no-straw or a much finer straw, sifted for a smoother finish. Animal and human hair have been used too.