Those thin layers applied as taping mud, joint mud, or surface texture layers have various compositions but the same mud can be used for all of these applications. Typically, there are variations in the formulas related to spreadability or stiffness. Add synthetic foam bits and you get popcorn ceiling texture but you probably want to add fiber to help hold it together. Chrysotile asbestos was an added component to some taping muds up until the late 1970s or early 1980s, but is also present as a naturally occurring contaminant in some of the mineral fillers used in this material. This became recognized in the early 1980s and compositions shifted to fillers such as crushed perlite or other non-talc sources. Talc deposits commonly contain chrysotile as a naturally occurring contaminant, which is why we no longer powder baby bottoms with it!

From a regulatory perspective, the application of the mud dictates how the material is regulated. Surfacing layers that cover the entire surface of the wall versus mud applied to cover only the drywall tape seams and joints, are regulated differently even though the surfacing layer may be the same composition as the tape mud. If sampled correctly, i.e. in such a way to include the entire thickness of the wallboard (drywall or sheetrock) layer and the tape or joint mud layer, and the lab composites the asbestos contents of the layers, the total percentage is no doubt 1% or less due to the relative thickness of the layers. However, if the same mud is thinly spray applied to the wall as orange peel texture, regulations do not allow for a composite sample and asbestos containing orange peel is regulated the same as popcorn ceiling texture. This is true regardless of how many paint layers overly the mud and often there is more paint than mud in the sample. Ultimately then, whether the mud layer is regulated may depend on the analysts ability to separate it from surrounding layers and this can be very dependent on sample size, manual dexterity of the analyst, and how well the paint clings or has been absorbed into the mud.

Wallboard (drywall or sheetrock) and tape or joint mud are the only materials that can be composited for a percentage of the total in the asbestos regulatory world. This is because it makes good sense to treat wallboard with tape and/or joint mud as a wall ‘system’  since volumetrically the tape and joint mud are such a small percentage of the whole. It is not impossible to identify tape and joint mud while collecting samples, but it can be very hit or miss in anyone’s sampling scheme. It is possible to intentionally attempt to avoid the muds in order to increase the chances of ‘No Asbestos Detected” and  on the flip side I see samples come into my lab all the time that are only the mud (without wallboard) even though the sample is described as wallboard on the chain of custody. Should the mud described as wallboard contain 2% chrysotile, and the lab fails to properly identify it as mud versus wallboard, the result could erroneously be used to require abatement of the wallboard. The proper differentiation between orange peel mud and the tape mud is also important. Calling orange peel mud tape mud on the lab report could result in a failure to recognize a regulated surfacing material.  The lab analyst can not always make the proper call on what type of mud is present, especially when the sample size is too small or the material has been broken up too much during sampling. The standard sized coring tube that some survey people use to sample wallboard does not give adequate sample volume in my opinion and hinders proper interpretation of mud/wallboard systems. The survey people would understand this if they were analyzing their own samples.

Orange peel texture muds, especially from the 1960s, can contain fine coated fibers that do not give good dispersion staining colors due to interference from clay binders and/or paint. I think the heavy coating on the fibers is due to the spray application and some of the spray guns are more prone to coating the fibers. I find other labs do not always report the coated fibers as asbestos even when they have the proper morphology. Getting good correlation between labs on the asbestos content in orange peel muds has been frustrating.

Walls are repaired with new tape mud and spackle quite frequently. It is impossible to guess where all the different muds are but it is possible to sample in such a way as to prove 1% or less asbestos or whether the mud is tape/joint/repair mud versus a texture layer. With an appropriate number of samples it can be determined that there is 1% or less asbestos in the wall (or ceiling) system and treat accordingly. In my opinion, it takes more than 2 samples to understand a wall/ceiling system. Multiple samples should be collected from area where each type of suspected mud is present. Samples must also be collected from areas where you think the mud is NOT. It is not possible to differentiate repair mud from non-textured surfacing mud used to float an entire wall without multiple samples.

It is difficult to correctly identify mud layers based on the lab reports supplied by most asbestos labs out there. This is because it is not the analysts job to identify which type of mud is present, it is the surveyor’s job. Most lab reports describe a mud as ‘white powder’ and do not give adequate information to help the surveyor figure out if different compositions of muds are present or whether the mud is tape or texture mud. Unless your lab analyst also has experience with building materials, they may not appreciated the difference in application of these mud layers and they do not necessarily care about the distinctions as interpretation of the data is the problem of the surveyor. In the field, the surveyor often does not know what they are sampling because they are not seeing the material under the microscope and these layers are so thin it is often not possible to see all the layers anyway. Unless the sample happens to delaminate across the mud surface, the mud layer may not be recognized until under the stereomicroscope. Obviously, older mud layers under a thick new orange peel texture layer may not be recognizable in the field and it is up to the lab analyst to call this out.

It takes years of training to become familiar enough with mud compositions to recognize an anomaly such as the difference between muds and asbestos textured paints.  Some texture paints are very similar to tape mud and actually designed to be used as tape mud, repair mud, or thinned and used as paint. They came as a dry powder and you added the amount of water to get the desired consistency. There are other asbestos paints with more paint like binders. I know of one instance where an Artex type textured paint was misidentified as tape mud. The analyst simply reported the material to be ‘mud’ and because it overlay wallboard it was presumed by the demolition contractor and regulatory person reading the lab report to be tape mud. The regulatory person prompted the lab to composite the results so they did, never having any idea that it was in fact surfacing. I have also seen instances where tape mud was incorrectly reported to be surfacing because it was included in a popcorn ceiling sample and the lab analyst failed to call that out on their report.

Many times the asbestos content of mud is around the 1% mark. It takes just one sample over 1% to make the entire homogenous sampling area regulated ACM so it is critical that the analyst be properly calibrated.

Many years ago, the difficulty in quantifying asbestos in mud materials was addressed by adding the point count technique as a requirement. According to the rule, materials found to contain 10% or less asbestos should be verified by the point count technique unless treated as ACM. Practically speaking, point counting would be advised for all samples found to contain 3% or less, depending on how well calibrated the lab. It should definitely be considered for materials at or near the 1% mark before any decision is made whether the material should be treated as regulated ACM. In my own lab, a sample result of 1-2% asbestos has about a 50-50 chance of point counting below 1%. I know some people who have been very disturbed about the subjectivity of asbestos analysis. To my knowledge point count by PLM is still the most accurate way to determine the asbestos content of mud materials. I have seen results from gravimetric reduction analysis on mud materials that makes me question that method, although OSHA currently considers it the most accurate test method for determining asbestos content of wall/ceiling materials.

It may not be possible to make the quantitation of the asbestos content any more accurate, but the common misidentification of mud layers as surfacing materials is something I think should be addressed by regulatory agencies. It is currently legal to have an asbestos abatement contractor survey your building and apply their own interpretation to your mud layers. Not that some do not do a perfectly fine job of this, but I suspect the temptation to make mud layers into surfacing (i.e. $$ for them) is hard not to do for some of them. I have known several instances where this happened in demolition situations where work was stopped at the debris pile stage because there was no survey and concern had been raised about possible ACMs. In response, abatement contractors were called in who surveyed the debris, found pieces of wallboard with thin mud layers, and based on a single sample called it a surfacing layer. The implications of that is now the whole debris pile is contaminated with friable asbestos and has to be abated and usually as soon as possible.

When these thin mud layers have no obvious surface texture or one is present that may be only be due to multiple paint layers, the distinction between repair/ttape mud  versus surfacing can only be determined with multiple samples. In one such example where an abatement contractor had called a thin mud layer surfacing, I was asked to re-analyze the sample originally done by another lab to verify the asbestos percentage.  What I received was a small thin chip of material that was paint with an attached soft white mud layer that could not be interpreted as to what type of application the mud had been used for. Compositionally it resembled US Gypsum Texture Paint product in my collection that contains an asbestos content slightly above the 1% mark. On the box, there are directions on how to use the product as either tape mud, spackle, or paint. My client who was being fined for improper removal of surfacing was totally at the mercy of the abatement contractor’s interpretation of the material and once they had cleaned up the debris pile there was no way for another consultant or regulatory people to make a determination whether it was surfacing or not. Don’t let this happen to you! Having the entity that stands to profit from the clean up of your pollution may not be the best entity to identify your pollution.

If you made it this far, you should know the photo above is of an asbestos textured paint, not tape mud. I believe this to be an Artex type textured paint. It is visible as the white chunky layer overlying the drywall paper and under green and off white paint layers. The chunks are chrysotile. The binder includes paint like binders which makes this different from tape mud and other types of texture paint. A troweled on texture was given to the material during application. This was visible in one room only. Elsewhere the layer had been covered with newer orange peel mud layers but was still obvious under the microscope as the chrysotile fibers were a distinctive size and the binder was also distinctive. The only way for the survey person to know this layer was present throughout as surfacing would be to have the analyst bring it to their attention by making it clear in the lab report.