Answers to your questions about Harmonite®

As more and more formulators turn to Harmonite for application solutions, they want to learn more about its properties, performance benefits and blending characteristics. Here are answers to some commons questions:

Harmonite — FAQ's 

Harmonite is a finely divided, free flowing, organic-coated/inorganic composite powder rich in asphaltenes and resins. It's a versatile, multi-functional and operation-friendly base compound or performance additive that:

  • Can improve formulation performance characteristics in adhesives, sealants, coatings, rubber compounds and other applications.
  • Allows simpler, more economical formulas — Harmonite can eliminate or reduce the usage of multiple, and often more costly, ingredients.
  • Dramatically reduce mixing time, up to 50% in some cases, with lower power consumption and increased throughput.

Lab data and end-user feedback have indicated that Harmonite provides different functionality in different applications. For example, in rubber compounding, it has been shown to act as a plasticizer and homogenizer, and a tackifier to improve rubber-to-metal adhesion, while reducing cycle times at the same time. Others have used Harmonite as a rheology / flow modifier to control viscosity, while others have used Harmonite to increase tack and internal adhesive strength in Hot Melt PSA's and other sealant applications. Others report improved abrasion resistance in belting and hose applications.

Users consistently report simpler formulas, lower formula and operating costs, and improved product performance. Users have replaced and reduced consumption of multiple ingredients simultaneously, many of which carry significantly higher costs. This helps improve inventory management and improve cash flow for the user as well. In addition, because Harmonite blends so readily, end users have reported shorter mixing times, which directly impacts Cost of Goods Sold (same amount of volume in less time and with less labor) and/or Return on Capital (more volume through the same capital equipment base).
Others have reported that their plant air quality was actually better because Harmonite was less ‘dusty’ than the powdered clay it replaced.

In many cases, yes. Harmonite has been shown to replace both ground and precipitated forms, along with ingredients like powdered coal, hard and soft clays, and more. Harmonite has been proven in HMPSA applications, for example, to both lower total usage cost and improve formula performance when substituted for calcium carbonate.

Carbon blacks and Harmonite function very differently – carbon black primarily by physical entanglement, while the organic phase of Harmonite is polar and resinous, exhibiting polymeric behavior, cross-linking and addition type chemical reactions (hydrogen bonding, Van der Waals). The inorganic phase of Harmonite is more blocky in structure than carbon black, so it doesn't provide the same kind of physical entanglement.

As a recycled product, Harmonite is keeping used shingles out of landfills and returning them to beneficial use in various products that are designed by end users to last for many, many years.  Like any raw material, users should review the SDS and take normal workplace precautions when handling and using Harmonite. Please also refer to our statement on compliance with various environmental communication regulations like USTSCA, California Proposition 65 and EU REACH.

If you have a very tight formula spec that cannot handle small variations inherent in Harmonite, or if your plant is not designed for handling powders like Harmonite, it might not be a good application for you. Likewise, although Harmonite is compatible with a wide variety of rubber operations like injection, transfer and compression molding, if you have a surface-critical extrusion specification, you may see objectionable surface defects due to the particle size distributions in Harmonite.

Harmonite has been proven to be a very economical choice – replacing multiple, often more expensive ingredients, and improving operational costs through shorter batch cycle times.

As a recycled product, Harmonite does exhibit some variability with respect to the amount of organic content (+/- 3%).  All inbound waste shingles are from single layer residential homes only, and inspected and tested to ensure no asbestos is present. As a result of the large quantity of shingles, coupled with our process, we are able to deliver a very consistent product with respect to moisture content and sieve analysis. Prior to shipment, all lots are tested for moisture content and must be < 1% by weight.  Sieve analysis must indicate that >=97% of particles must pass through the given screen size for the specific Harmonite product. In more than four years of operation, the company has had no returns as a result of out of specification material.

All products are available in 2,000 pound supersacks.  Harmonite 40 is also available in 40lb micro-perf poly bags and Harmonite 70 is available in 35lb microperf poly bags. Depending on end use processing temperatures, the poly bags can be used as a melt inclusion bag.

Harmonite is made via a patented and proprietary thermal/mechanical process.

Harmonite flows readily with minimal agitation upon removal from bags or super sacks – it exhibits moderate compressibility with little to no cohesive properties during storage and transit.  Some settling during shipment is normal and is not detrimental to normal processing. However, placing heavy objects/weight on top of Harmonite can compress it to the point of forming hard clumps that are difficult to process. Do not place heavy weights on top of Harmonite powder.  Do not stack pallets of Harmonite. If stored outdoors, material should be tarped, kept dry and not subjected to extreme temperature swings.


No, RSS has been in commercial operation since mid-2015 and is a wholly owned subsidiary of The Dupps Company, an 85-year-old, 4th generation family owned and operated manufacturer.

RSS has had >99.5% on-time performance record during the past four years.  RSS maintains a modest buffer stock of Harmonite 40 and routinely fills spot truckload orders in less than a week.  We ask that larger volume and Harmonite 70 & Harmonite 100 customers place orders into a production schedule with a minimum of 3-4 week notice.  RSS has a stable supply chain, sourcing raw materials from within ~100 miles of the greater Atlanta metro area to ensure stable supply of feedstock to our plant.

 Depending upon product mix, the RSS plant in Forest Park, GA has a nominal nameplate capacity to produce up to 50,000 tons per year.

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Harmonite Characteristics Summary

Find out how Harmonite can improve your formulation — contact Ken Thomas, Email:; 937-855-6555

Harmonite 40 Product Data   •  Harmonite 70 Product Data  •  Harmonite 100 Product Data
 •  Harmonite C Product Data  •   Harmonite Safety Data



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For questions about Harmonite, please contact Ken Thomas; 937-855-6555