I plan to replace a section of my ceiling that has a bad crack. The house was built in 1920. I noticed on one piece of exposed plaster (that's about a quarter-inch thick) that there appears to be two sections: the surface plaster, which is white and about 1/8 thick, and then a grayish, crumbly material that makes up the rest of the thickness.
Is there any chance that the gray material has asbestos in it? Is there a quick way for a layman to test it for asbestos?
The answer is, Yes. In a house of that period there could be asbestos in the plaster. The answer also is yes for sampling it. Typically the percentage of asbestos is fairly low in this kind of material (anywhere from trace amounts to 5% is common). According to federal regulations, if it comes back less than 1% asbestos in the sample, it is not considered a regulated asbestos containing material.
If you do a google search on asbestos sampling or testing you will find plenty of labs willing to analyze your sample and take your money (plan on spending $30 + per sample). Hope this helps.
Yes, any of the layers of plaster (including the smooth white layer) can have asbestos in it.
Since you own your home, you can legally take a sample. The lab I use charges about $7 per sample.
Here's how one would take a sample:
1. Wear a respirator fitted with N100, P100, or R100 filters (the filter type will be labeled on the filters). Be sure to test the fit first to make sure there aren't any leaks.
2. Place a plastic dropcloth under the work area.
3. Thoroughly wet the plaster with a spray bottle filled with water and a few drops of dishwashing liquid (not enough for the water to get sudsy). Keep spraying while collecting the sample so that it stays damp. The idea here is to prevent any dust from being generated.
4. Carefully cut a piece of the plaster and place it into a ziplock baggie (an apple corer may work if it's sharp; otherwise use a sharp pocket knife or utility knife. It's okay if the sample does not stay in one piece). Sample size needed is small - just a peanut sized amount.
If possible, keep each layer of plaster separate in a separate baggie, and label them accordingly. That way, the results indicate which layer(s) contain asbestos.
5. Use a damp rag or sponge to clean up any remaining dust. Also use another one to wipe off your respirator. Wrap these up in the drop cloth and throw it away.
6. Wash off tools, hands, and respirator.
7. Place each sample in a second ziplock baggie and label it with whatever info the lab wants (usually date and your name, and a sample name or number).
8. Mail sample to lab. No need for overnight or ice etc.
DISCLAIMER: This information is meant for information only. Use at your own risk.