Respirable Crystalline Silica

A new federal rule aimed at protecting workers in general industry from respirable crystalline silica exposure takes effect on June 23, 2018.   “General industry” includes plastics manufacturing where precipitated and fumed silica may be used in plastics as fillers, thickeners or softeners and to aid flow for certain processing needs.

Respirable crystalline silica is commonly found in quartz, cristobalite and tridymite.  All of these forms may become respirable-sized particles when workers cut, chip, drill, sand or grind objects that contain crystalline silica.

Thermoset, copolymer and thermoplastic syntactic foams all contain hollow glass microspheres as a key element to provide low thermal conductivity, low thermal expansion and general high stability.  The thought that cutting or machining the microspheres, particularly from machine shops working with the thermoset group of syntactic foams, raised questions to our technical group about the levels of respirable crystalline dust that may be produced.

Fortunately for industries in which HYTAC syntactic foam is used, there appears to be little concern.  The glass microspheres used in HYTAC syntactic foams consist of an engineered, respirable crystalline-free glass designed specifically for use in applications where thermal, mechanical and other conditions are too harsh for standard glass.  A synthetic crystalline-free silica is specified and used as the flow agent for all HYTAC microspheres.

Testing for industrial hygiene is a part of any manufacturing process and should be conducted on a regular basis. When it comes to HYTAC materials, we have been unable to detect any areas for concern with the upcoming OSHA ruling for our internal testing or that will result from your own testing.

Respiratory concerns aside, syntactic dust can be harmful to equipment, filtration systems and general housekeeping.  We continue to hear the benefits of our HYTAC copolymer (FLX, FLXT and C1R) syntactic and HYTAC thermoplastic (B1X and XTL) syntactic foams in all of these areas.  The photos below show the typical “dust” that results from machining HYTAC syntactic foam.


Contact CMT directly with any questions or concerns.