Sorry for the tardy response.
We have pumped earthen plaster mixes previously with our modified
Thompson plaster piston pump. It also delivers clay slip
exceptionally well. I am fairly certain that my friend and colleague
Tina Therrien has done the same through her auger pump.
In our case however, we don't spray it on but rather pump it at a
higher rate of speed/volume through a specially built trowel/paddle
that allows the mix to ooze out through a slot on the underside of the
tool and thus get applied directly to the wall sort of like the
automatic recharging paint rollers sold at building supply stores. I
believe that there was an article on this style of "power trowel"
(which we had built for us by a then business partner of Tina's) in a
back issue of The Last Straw in 2005 or 06.
I would hazard the same guess as your own, that the narrow nozzle on a
sprayer would not be suitable for spraying high fibre content mixes.
If you think you might be interested in a power trowel to try, we are
currently selling our pump on kijiji (we now perform fewer plaster
gigs a year and do more general contracting on the same homes instead,
so we needn't race through multiple plaster jobs each year which the
pump had allowed us previously to do) and I would be happy to separate
one of the trowels (the pump needs only one) to see it put to use.
Contact me off list if this is of interest.
Quoting ryanv3120 <rainer.vollmerhaus@...
> Hey there,
> Does anyone have experience with mortar sprayers that they are
> willing to share? I have am spraying both a lime/cement mortar and
> a clay plaster. Since they both have chopped straw in them, it
> seems like the straw should clog up the nozzles. Also, do the thick
> mixtures easily go through the hopper? It seems like a regular clay
> mixture would stick to the sides of the hopper and not go through
> the system?
> Thanks in advance,