I found some material (pictures below) that I'm concerned might be asbestos, while demolishing the ceiling of a house in the UK which was built in the 1920's.

The material looks like concrete, but it has some brown hair-like material mixed in.

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    Thank you for using the DIY internet asbestometer , The odds of obtaining an answer you can be sure is correct is Zero. DISCLAIMER The DIY asbestometer is for entertainment purposes only and should not be used for a definitive answer.
    – Alaska Man
    Commented Mar 20, 2019 at 18:38

4 Answers 4


No, it is plaster with animal hairs in it, probably pig or cow hair.

To determine if there are asbestos fibers inside the plaster, break it apart and examine with magnifying glass. Asbestos is a fine white fiber. It looks like this:

asbestos in plaster

The fibers on the right are asbestos, those on the left are animal hairs. Asbestos fibers will be colorless, very fine and clumped together, like in the photograph. Animal hairs tend to be by themselves and have color. Notice that an animal fiber will be rounded, but asbestos tends to be stiff like a corn stalk with crinkles or breaks in it.

  • Actually, it is likely to be horse hair, from manes and tails. Commented Aug 26, 2015 at 1:55
  • @Craig What makes you say that? Nearly all plaster hair is from standard mass slaughter animals (pig/cow). The horse hair thing is just a myth. It is true that long, long ago (like in 1800) high quality plaster did use horse hair, but that has not been the usual case for 200 years or more. So, unless the plaster is like 250 years old, it is probably pig or cow hair. Commented Aug 26, 2015 at 2:02
  • Sure, hair from cows and pigs is also used, although horse hair is longer and stronger. You don't have to kill a horse to trim its main and tail and sell that. Way, way less than 200 years ago some of the finest ropes made were made from horse hair. You can still buy horse hair ropes, even on Amazon.com of all places. Also this, and finally this. Commented Aug 26, 2015 at 3:57
  • This page has a handy phone number, in the UK of all places, where you can order horse hair by the pound for use in plaster mortar. That page also says; "Unfortunately, it only takes one generation for knowledge to be lost; there are still a few plasterers in their sixties who were taught to use lime as apprentices, but few of them are passing the skills on." The point of the article is of course using horse, goat and cow hair to reinforce the lime for plastering walls and ceilings. Commented Aug 26, 2015 at 3:58
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    @TylerDurden - The fibres on the right of your pic look a lot like the fibres I see when I snap plasterboard. This is brand new plasterboard, which makes it extremely unlikely that I'm seeing asbestos; not that I know what the fibres I see actually are. I'm not denying that the ones in your pic are asbestos, but I don't think visual identification is as easy as perhaps you make out.
    – AndyT
    Commented Aug 26, 2015 at 16:09

Since you've already got it in a bag, send the bag off to a test lab. It's the only way to know for sure.

  • This is not terrible advice. There's nothing that says the material couldn't contain both asbestos and animal hairs. It couldn't hurt to test it. Commented Aug 26, 2015 at 1:56
  • if you are going to send things in for testing, please double bag all samples. Also labs need a very small amount, and do not like getting giant bags.
    – Andrey
    Commented Mar 20, 2019 at 21:09

I used to work for an environmental company where we did asbestos management plans. There is no way to identify something as asbestos without a lab test. The only other thing to do is figure out when the substance was put in. For instance in the US asbestos was banned in 1989 so we know what any construction after that date does not need to be tested.


Asbestos is a blanket term for several different minerals. The white asbestos, a mineral called Chrysotile is the most common and most of the others were used for various reasons including the same reasons Chrysotile was used. I've had several unexpected positive asbestos results. The used to put that stuff in everything. So in short you can't tell without a lab test.

Asbestos didn't really get much use until the 1930s but that doesn't mean that you should work without a mask or that it's definitely not asbestos. The bottom line is that, if it's old proceed with caution. Back in the day people would take doses of mercury and go to the barber for some blood letting(the practice of removing "bad blood" to cure ailments). That's what the red twisted stripe on a barber pole symbolizes. On the lighter side of things, asbestos isn't as bad as it seems for short term exposure. The asbestos abatement industry that has spung up in recent decades will have you think that it's a death warrant. You don't want to breath that stuff in and you don't want to leave any loose fibers around but 1 pack of cigarettes never killed anyone. The photos don't look like anything I've ever seen containing asbestos but it's old, who knows what's in it. Proceed with caution. Be clean, wear a high quality mask and use heavily filtered vacuum. By all means send it out for a test, they may find something worse than asbestos.

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