Select a sealant for the job

Neutral Cure silicone rubber sealants are the only sealants recommended for use with COLORBOND® steel and ZINCALUME® steel. Look for the words "Neutral Cure" on the sealant cartridge to make sure.

The advantages of neutral cure sealants are:

• They provide good adhesion
• They do not require a primer except in extreme service conditions
• They resist extremes of both heat and cold while retaining good flexibility
• They provide very high resistance to the damaging effects of ultra violet rays (although exposure to UV rays should be avoided if possible)
• They do not have acidic additions which may adversely affect steel.

These factors ensure neutral cure sealants give long life compatible with the performance of COLORBOND® steel. Sealants should be applied to avoid exposure to UV rays (i.e. sandwiched in the lap), and so they don't create water run-off and dirt tracks down a roof or facade.

Any other generic type of sealant considered should possess similar properties to neutral cure silicone rubber if long term performance is required.

Paint will not adhere to a surface contaminated with sealant. To improve adhesion light abrasion is required to remove traces of silicone. Care should be taken to avoid damage to the protective exterior finish of the steel surface. Alternatively very thin coats can be used. The second coat will adhere reasonably well. A better alternative is to use paintable silicones which are available and are very useful where post painting is required.

This information is intended as a guide only. For more information, please see Technical Bulletin TB 09 - Sealants for Exterior Finishes (Nov 2003, 140 KB).