FREQUENTLY ASKED QUESTIONS
01. What are Chomerics Cho-Bond (pronounced “ko-bond”) RTV products? Top
Chomerics provides electrically conductive, room temperature vulcanizing (RTV), moisture cured silicone adhesives and sealants. All of our RTV systems are silicone based and vary by having different types of conductive filler. Due to the filler loading differences, each material has different mechanical properties. Please see the specific data sheets for details.
This family includes Cho-Bond 1030, 1035, 1038 and 1075. [Cho-Bond 1029 is a two component system and is not part of the moisture cure RTV family.
This is a link to a product summary showing the typical properties of these materials:
http://www.chomerics.com/products/documents/Compoundssel_guide.pdf
02. Where can I find technical data sheets and MSDS information? Top
You can find all of our technical data sheets, MSDS´ and other literature on our web site at:
Product Literature Library
03. What is supplied in a kit of Cho-Bond RTV material? Top
Cho-Bond RTV material is typically supplied in two sizes, a smaller foil tube version (2.5 ounce or 4.0 ounce by weight) and a larger caulking cartridge version (10 ounce or 1 pound by weight). [Note: The MSDS for the Cho-Bond and the Primer 1086 are included in each shipment.]
The smaller version comes with a key to help squeeze out the material, a plastic nozzle and a 3 dram vial of our silicone Primer 1086.
The larger version comes vacuum-sealed in a foil-lined bag with a desiccant, a 4 inch long by .093” diameter nozzle and a 3 dram vial of our silicone Primer 1086.
04. What is the shelf life of Cho-Bond RTV material? Top
Cho-Bond RTV has a shelf life of 6 months from the date of manufacture. It will have 80% minimum shelf life remaining when purchased directly from Chomerics.
Material bought through our distribution network usually has a –55 suffix on it, which means that product has a shelf life of 9 months from date of manufacture at Chomerics. You will need to speak with your specific distributor to determine the amount of shelf life remaining on his stocked material.
05. Is there Shelf Life extension available for Cho-Bond silicone RTV? Top
YES – under the following conditions.
06. Can I speed up the cure time of Cho-Bond RTV? Top
NO – this material cures on exposure to atmospheric moisture. It cures best at room temperature and 50% relative humidity. The material cures from the outside in, so it may appear cured, but may still be uncured beneath the surface of the bond. Uncured material will not exhibit the mechanical and electrical properties that we specify on our data sheet.
However, it is common place for customers to determine how much cure time is actually necessary for their specific application. Some customers have found 24, 36 or 48 hours works for them in their particular application. The end user is responsible for any failures which occur when not allowing the full 7-day cure.
Note that as long as the material continues to be exposed to the atmosphere, it will continue to cure. So, for example, if 48 hours has been determined to be sufficient for a particular application, as long at the material continued to be exposed to the atmosphere, if it were still uncured, it would continue to cure. Sealing the Cho-Bond material in a bag would cut off atmospheric moisture, and may never allow for full cure.
07. What do I do with the Chomerics Primer 1086? Top
Primer 1086 is a silicone primer used to enhance the bond between a metal surface and the silicone Cho-Bond material. THE PRIMER IS NOT MIXED WITH THE CONDUCTIVE RTV. THE ADHESIVE IS A SINGLE COMPONENT SYSTEM AND CURES WHEN EXPOSED TO THE ATMOSPHERE. The primer does not need to be applied to an elastomer gasket, only to metal surface(s) that needs to contact the Cho-Bond. Chomerics strongly recommends that you use the Primer 1086 so that a strong bond is attained.
To apply Primer 1086, thoroughly clean and degrease the surface to be primed. Solvents such as Isopropyl Alcohol (IPA), Toluene, Methyl-Ethyl-Ketone (MEK) and Acetone are typical cleaning / degreasing solvents. Allow the solvent to flash off the metal surface, then apply a coat of Primer 1086 by wiping a thin film onto the metal surface. Use adequate ventilation. A typical applicator is a cotton swab or clean lint free rag. Allow the primer to dry/cure from 30 to 60 minutes. (The primer is also a moisture cure system). Next apply the Cho-Bond material. Please note that a primed surface that is not bonded within 4 hours should be re-cleaned and re-primed as the original primed surface will no longer function properly.
Technical Bulletin 33 is very helpful in listing surface preparation for various substrates.
08. Can I break the joint bonded or sealed with Cho-Bond silicone RTV? Top
YES – with some effort. As a silicone based system, the Cho-Bond will soften and swell when exposed to certain solvents, in particular Toluene. Methyl-Ethyl-Ketone and Acetone will also work to a lesser degree. In a well ventilated area, using a wooden tongue depressor or similar non-metal tool, apply the solvent to the joint and then work the joint removing the cured Cho-Bond. Re-apply the solvent as more Cho-Bond is removed until the joint can be broken. Continue to repeat this process until all of the Cho-Bond is removed.
09. What is the minimum buy requirement for Cho-Bond silicone RTVs? Top
Each material has its own minimum buy requirement direct from Chomerics. Please Contact Us and speak with a Chomerics Inside Sales Representative to get the details.
10. What is the typical lead time for Cho-Bond silicone RTVs? Top
The typical lead time for these materials is 3 weeks. Chomerics does not typically stock this material due to shelf life concerns.