FAQ

How is viscosity measured?

Due to the thixotropic characteristics of most gap filler materials, special consideration should be given to the test method(s) used to determine viscosity of these materials. Because the material viscosity is dependent on shear rate, different measurement equipment testing under varying shear rates will produce varied viscosity readings. When comparing apparent viscosities of multiple materials, it is important to ensure that the data was generated using the same test method and test conditions (therefore the same shear rate). Test methods and conditions for BERGQUIST^® products are noted in the individual Technical Data Sheets.

How are pot life and cure time defined?

Two-part gap filler systems begin curing once the two components are mixed together. Henkel defines the pot life (working life) of a two-part system as the time for the viscosity to double after parts A and B are mixed. Henkel defines the cure time of a two-part material as the time to reach 90 percent cure after mixing. Two-part gap filler materials cure at room temperature (25°C), or cure time can be accelerated with exposure to elevated temperatures.

How should I store my gap filler?

Unless otherwise indicated on Technical Data Sheets, twopart gap filler products should be stored in the original sealed container in a climate-controlled environment at or below 25°C and 50% relative humidity. If stored at reduced temperatures, materials should be placed at room temperature and allowed to stabilize prior to use. Unless otherwise noted, all cartridges and tubes should be stored in Henkel-defined packaging with the nozzle end down.

Do temperature excursions above 25°C affect the shelf life?

Short periods of time above the recommended storage temperature, such as during shipping, have not been shown to affect the material characteristics.

Can I use my gap filler after the shelf life has expired?

Henkel does not advocate using gap filler products beyond the recommended shelf life and is unable to recertify material that has expired. In order to ensure timely use of product, Henkel recommends a first-in-first-out (FIFO) inventory system.

Does gap filler have adhesive characteristics?

Although gap filler is not designed as a structural adhesive, when cured, it has a low level of natural tack, which will allow the material to adhere mildly to adjacent components. This aids in keeping the material in the interface throughout repeated temperature cycling and eliminates pump-out from the interface.

How do I mix a two-part gap filler?

Disposable plastic static mixing nozzles are used to mix parts A and B together at the desired ratio. Static mixers can be attached to the ends of cartridges or mounted on automated dispensing equipment. They are reliable, accurate and inexpensive to replace after extended down times. Unless otherwise indicated, mixing nozzles with a minimum of 21 mixing elements are recommended to achieve proper mixing.

What container sizes are available for gap filler?

Two-part materials are available in several standard dual cartridge sizes including 50 cc (25 cc each of parts A and B) and 400 cc (200 cc each of parts A and B). Gap filler products are also available in kits of 1200 cc (two stand-alone 600 cc containers, one of each part) and 10-gallon (two 5-gallon pails, one of each part) sizes for higher volume production. Other special and custom container sizes are available upon request.

Is gap filler reworkable?

In many cases, gap filler can be reworked. The ease of rework is highly dependent on the topography of the application as well as the coverage area.

What is the tolerance on the mix ratio?

Two-part materials should be mixed to the stated mix ratio by volume within a +/-5% tolerance to ensure proper material characteristics. If light-colored streaks or marbling are present in the material, there has been inadequate mixing. Henkel recommends purging newly tapped containers through the static mixer until a uniform color is achieved. In order to ensure consistent material characteristics and performance, BERGQUIST^® two-part systems are to be used with matching part A and B lot numbers.

Should I be concerned about gap filler compatibility with other materials in my application?

Although not common, it is possible to encounter materials that can affect the cure of a two-part gap filler. A list of general categories of compounds that may inhibit the rate of cure or poison the curing catalyst in gap filler products is available to help assist with material compatibility evaluation. Please contact your local Henkel representative for more details.

What options are available for dispensing material onto my application?

Henkel can provide manual or pneumatic applicator guns for products supplied in dual cartridge form. Gap filler supplied in high volume container kits can be dispensed via automated dispensing equipment for high speed in-line manufacturing. Henkel and our other experienced automated dispensing equipment partners can further assist our customers in creating an optimized dispensing process. For information regarding dispensing equipment, contact your local Henkel representative. For some materials, screen or stencil application may be an option and should be evaluated on a case by case basis.