After dispensing, Dow Corning ® Adhesives are cured at room temperature or by
heat, depending on the specific product being used (see data sheets for curing
details of individual products).
For best results, surfaces to be adhered should be clean of grease, oil and
other surface contaminants. Common cleaners for substrate preparation include
Dow Corning’s line of OS Fluids, isopropyl alcohol, toluene and acetone.
Room Temperature Cure
A room temperature cure process can be used for adhesives that are either
moisture cure or condensation cure products. After being applied, the adhesive
is simply allowed to cure at ambient room conditions. Condensation cure
products will cure in 30 minutes to 4 hours. Moisture cure products will
require several hours to cure or need to be left undisturbed overnight as the
cure is dependent on moisture from the air permeating through the material.
One-part moisture cure products will not cure in thick section (they are
generally restricted to bond lines of 0.25 inch/6 mm or less). They are also
not meant for confined cure, since they need moisture from the atmosphere for
curing. For thicker bond lines, a rule-of-thumb is that 0.25 inch/6 mm
thickness will take roughly 7 days for full cure under normal room temperature
conditions. Two-part condensation cure products will cure in either thin or
thick section and can cure when confined. Refer to the product data sheets
(link to Family data sheet) for typical curing times of individual products.
Heat cured adhesives can be either one-part or two-part products. Typically,
cure and the development of adhesion are not achieved until the material is
heated above 100C. Newly developed formulations cure more quickly at
temperatures as low as 90C. At these temperatures, the adhesives will
generally cure in about an hour. For all the heat cure adhesives higher
temperatures will result in faster cure. Limitations on cure speed are
generally dependent on the temperatures that the unit and components are able
to withstand. Heat curing can be done in a batch or conveyor oven. Heat cured
adhesives will cure in either thin or thick section and can cure when confined.
The heat cure adhesives can have their cure poisoned (inhibited) by certain
materials due to the type of catalyst used, resulting in poor or incomplete
cure. With a mild case of inhibition, the adhesive can appear to be cured
normally, but adhesion is poor. If you have problems with poor cure or
adhesion, contact Dow Corning’s technical experts in the Application Center.