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Asbestos fibers in acoustic plaster done in the 1950's.

Dangling asbestos plaster. Acoustic plaster was reinforced by asbestos fibers.

This is to expand on my article, "The truth about asbestos in plaster". Here's a link to what I published in 2013:
Please check out what I say about sound ratings for plaster.

Acoustic plaster was a soft, weak plaster made for dampening sound. Asbestos fibers were used as a binder to hold this stuff together, like animal hair in lime and sand basecoat plaster. Lime and sand is soft and weak, and needed the binder to hold it together

Acoustic plaster was used mainly on ceilings in churches and schools to dampen sound. You can find acoustic plaster in areas where people congregated, like church narthexes, or areas outside the sanctuary. Usually in schools acoustic plaster was used in entrance hallways.

Acoustic plaster is easily identified. The plaster is soft and can be pushed in with a finger. It always has a rough texture, unless it has been coated over.

I'll tell you what I know. I have seen asbestos only maybe 3 or 4 times in my years of patching plaster in houses and government buildings, except for acoustic plaster. Acoustic plaster is probably half asbestos. I am referring to acoustic plaster done in the 50's and 60's. There is a new generation of spray on acoustic plaster that I am sure doesn't contain asbestos.

Asbestos was used in many of the hallway ceilings in the pentagon. I don't know why. A suspended plaster ceiling has a high fire rating. Maybe it was for strength. Almost all of these ceiling have been replaced over the years.

There is a building in Quantico marine base that had asbestos in the stucco, for whatever strange reason. Stucco on block has an outstanding fire rating so I don't know why asbestos was used, except maybe for federal waste. I know this from bid invitations I received. The project was to strip off all the stucco from the block on this huge building, and stucco over the block.

The asbestos fibers on exterior cement tiles (sometimes called asbestos tiles) made in the 1950's had large fibers. These were most likely used for reinforcment. The large fibers are probably less of a hazard from breathing. These days, polypropylene are made that are cheap and strong. These fibers are sometimes used in concrete and cement mortar and add strength.

Question:

I live in South Florida, in Fort Lauderdale. I have a house from 1958, I was trying to do a renovation but two of the GC's came to my house said that the plaster in the bathrooms could have asbestos. I am really freaked out about this issue, can you please give me some advice ?

Answer:

The only sure way to test for asbestos to take a small chunk out of the wall. You may be able to get a small piece by taking off a heat register or electrical receptacle cover. If you smash the basecoat plaster, you will be able to see the fibers if there is asbestos.