A: There are two classes of purging compound available – "High-Performance" and "Commodity-Grade". High-performance products (such as NOVACHEM's SuperNova™ Chemical Purging Compound) are intended for use in difficult purging situations. These involve very challenging materials like PEEK, fluoropolymers or Ultem, or very large and complex equipment including complex hot-runner installations and many extrusion or blow molding systems.

In contrast, commodity-grade products (such as NOVACHEM's InstaPurge® Purging Compound) are useful across a very broad range of common purging situations. They are effective with commodity resins like PE, PP, styrene and PVC as well as first-generation engineering resins like ABS, Nylon, acetal and even polycarbonate. These products are most appropriate for use in injection molding systems (including many equipped with hot manifolds) and in some simple extrusion systems.

High-performance purging compounds provide the maximum in purging effectiveness, but are more expensive and tend to be somewhat more difficult to use. Commodity-grade purging compounds provide ample purging effectiveness for most situations and are economical and easy to use. You should choose the class of purging product best suited to the materials and equipment that you work with. Remember – don't pay for more purging performance than you need!

A: InstaPurge® is different in several respects – and these differences combine to make it the best value available among commodity grade purging materials.

First, the InstaPurge® formula includes a blend of resins that are effective in displacing a wide variety of production materials across a wide range of operating temperatures. Second, this purging effectiveness is obtained without messy mixing, without adjusting temperatures, without time-consuming heat soak periods and without unpleasant odors. Finally, InstaPurge® contains a unique and exclusive ingredient that prevents it from adhering to the internal metal surfaces of the equipment so it is easy for the follow-on resin to displace. All of this comes at a price that compares very favorably to other materials in its class.

A: InstaPurge® can be used in a wide variety of purging situations, but it is most effective with either commodity resins (PE, PP, styrene, PVC, etc.) or first-generation engineering resins (ABS, Nylon, acetal, PC and others) processed in injection molding equipment.

You can use InstaPurge® with confidence on resins processed at operating temperatures from 350°F to 630°F (175°C to 332°C). (Consult the MSDS and the Instructions for Use for additional discussion about temperatures – these are available for downloading from our Document Library.)

InstaPurge® Purging Compound is highly effective when used in typical reciprocating-screw injection molding equipment, and has also been useful in simple extrusion systems and in some hot-manifold installations.

A: InstaPurge® Purging Compound is supplied in two grades – Unfilled and Filled. The Filled grade contains a chopped glass fiber material that provides additional "scrubbing" effectiveness for difficult purges. Here are a few cases where you should NOT use the Filled grade:

• In hot manifolds (hot runner systems).
• In extrusion systems unless the die and any screens or filters are removed.
• In systems that have internal flow passages of less than 0.040" (1.0 mm).
• In cases where the follow-on resin is of low viscosity (such as flexible PVC or LDPE) and might have difficulty displacing residues of the filled purging compound.
• In any case where the added abrasiveness of the filler causes concern about wear on soft or polished metal finishes.

In these cases, only the Unfilled grade should be used. In other cases, either grade may be used.

A: In most cases, between one and two system volumes of InstaPurge® material will be needed to effectively purge the system. Start with one system volume (i.e., the ounce-rating of the barrel for a normal injection molding machine) and increase if necessary. Thus, a machine having a 16 oz. barrel will usually require between one and two pounds of InstaPurge® Purging Compound.