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Rock lath plaster reinforced with?

I'm looking at renovating/improving a situation where the downstairs bathrooms has suffered through many owners since the house was built back in the 1900's. The walls on the first floor are original to the house and were built using rock lath, about a half inch of grey color mortar-like plaster and a white finishing coat of another type of plaster. The original bathroom wall also included hand scored lines in the finish coat to resemble tiles and a glossy green paint in the wet areas. Except for the holes cut in the wall for a soap holder etc. the walls are still extremely sound. However one of the many previous owners installed fiberglass paneling over everything using liquid nails, and nails and I'm looking at how to cover the wet areas around the tub and with what and how.
This is where I begin my question:
There is a fiber that is mixed into the grey plaster as reinforcement. It is not horsehair. My neighbor's house which was built in the same time period and judging by the interior probably finished by the same plasterer. In his house they used easily identifiable horsehair. Now, the fiber in my house is tan, about the diameter and length (4-5in) of a white pine needle. It's somewhat flexible and has pretty good tensile strength.

I have found unmixed fibers under the baseboards in other rooms, and as a result I have conducted a few tests on them outside. They ignite, meaning they will ignite within close proximity to a match and burn themselves out after consuming about 1/4-1/2 inch at a time. The burnt material is ash, and any reduced intensity of heat will have it turning black to a charcoal like effect.

Internet searches point towards hemp fiber? Has anyone run across something like this in their walls? I do live nearby a shipping port so perhaps the materials available to the house builder at that time would reflect a turn of the century shipping port. I have been cautious since discovering the fiber and the bathroom project has stopped while I evaluate shower-wall area options.

Any help is appreciated....

Re: Rock lath plaster reinforced with?

I was going to suggest hemp. Hemp at one time was readily available and grown on many farms up through WWII.

Re: Rock lath plaster reinforced with?

I have a resin based plaster product that will adhere to the existing lath, bond to remaining surrounding plaster, and is easily worked to the same level of surrounding plaster. It is not necessary to add fiber to this product for reinforcement. Just be certain that the lath is nailed firmly to the studs. It is sandable, and water resistant. This product can be used to skim coat plaster walls. It also adheres to wood, tile, glass, concrete. Please email [email protected]

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