'Plastic composition materials and products made therefrom.' U.S. In each case the amount of asbestos was quite high, and the Water absorptive capacity of the asbestos has increased the drying time of casts thus made. 2,526,066, such asbestos fiber was added as a means for retaining an expansive component of the plaster composition in place in the set cast. In one such use the asbestos fiber has been added to plaster primarily to improve the plaster workability or trowelling characteristics while in another instance, in the Croce Patent No. It should be observed also that in some instances asbestos has been used in plaster. 'Plaster compositions and products.' U.S. A top or white finish coat of smooth plaster.We think this material is meant to refer to what we've labeled the rough-coat or brown coat. The lab report refers to 'Grey plaster' wherein it found 1-5% chrysotile asbestos. Rock lath - a plasterboard or gypsum board nailed to the wood framed wall to serve as a plaster base.Notice that according to the lab report, this plaster wall is comprised of the following layers: Thanks to reader TD for providing this photo and asbestos test lab result that confirmed finding asbestos in this plaster sample. See ASBESTOS in DRYWALL Asbestos Confirmed in Rock-Lath Plaster Installation Some plaster products may also contain tremolite (a form of amphibole asbestos) as an inadvertent contaminant from asbestos mining of chrysotile, and also they may include vermiculite that, depending on where it was mined, also contains asbestos (Libby).īecause plaster was added to various wallboard products and drywall to improve its water resistance or fire resistance, in turn that means that additional drywall products manufactured between 19 or later may also contain both chrysotile and tremolite asbestos.Īsbestos was used as an ingredient in some plaster applications.Īsbestos was used in decorative plaster cornices, trim, ceiling medallionsĪsbestos was used also in acoustical plaster both as a direct asbestos additive and as an asbestos contaminant in plasters to which vermiculite or 'Zonolite' were added to produce a light-weight plaster having good acoustical properties.Īsbestos was used in plaster designed to have a high resistance to fire.Īsbestos was used in plaster additives to gypsum board or 'drywall' products to improve its moisture resistance (such as bath tile backer board) and to meet gypsum board fire resistance standards such as ASTM C630/C630M-03e1 Standard Specification for Water-Resistant Gypsum Backing Board (Withdrawn 2005 and replaced by ASTM C1396/C1396M) However that was not always the case, as we detail here.Īsbestos in Plaster and stucco, sometimes includes chrysotile asbestos in two forms: as a deliberate additive in fire-resistant plaster, in specialty plaster products such as casts or decorative moldings, and on occasion as an inadvertent contaminant. Modern plaster products and modern drywall and taping compound do not contain asbestos. Chrysotile Asbestos content in Some (not all) Plaster We also provide an ARTICLE INDEX for this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need. This article explains where & when asbestos is likely to be found in plaster used on building walls & ceilings.

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Lath and plaster wall texture