GC TOP 189

Thin-layer sealing for maximum corrosion protection

The GC TOP sealing systems developed by Hillebrand Chemicals (Top Coats) offer a wide range of applications for visually attractive surfaces with simultaneously improved corrosion protection. They are designed to be used with GC PASS passivation. On electro depositions the combination of these two coatings influences the chemical and mechanical resistance of the entire system.

GC TOP 189 has been optimised for the use on brake calipers or parts with a similar requirement profile. It is a particularly high-grade, inorganic sealing product with aqueous-based reactive binding components. GC TOP 189 is a sealing product that can be applied universally to zinc- and zinc alloy surfaces and offers a broad range of possibilities. Due to the new chemical structure, a thin film of less than 500 nm is enough to ensure the required corrosion protection. Chemical cross linking takes place at temperatures as low as 80 °C. As with pure silicate sealers, areas that receive too much coating due to application conditions are not prone to tinsel formation. A well balanced system of additives ensures uniform film formation. The dry film can withstand temperatures of up to more than 200 °C without any loss of corrosion protection.

GC TOP 189 is used as a 25% solution for rack parts which are exposed to extreme temperatures in continuous operation. Heating the bath to 50 °C is possible for better film formation. The dry film is already distinguished in an extremely thin layer of 300 – 500 nm by a very shiny visual appearance and suppresses irisation effects of the passivation.

Furthermore, a GC TOP 189 closed sealing film considerably delays the formation of white rust on zinc layers and also greying on zinc-nickel layers. The reactive components of the sealing product together with the passivation produce a particularly high performing corrosion protection unit which also offers secure infiltration protection in the event of any damage. Good corrosion protection is achieved after drying for just 15 minutes at 80 °C object temperature. If the coated component is exposed to a higher temperature during the later in-use phase, the corrosion protection increases significantly.

Corrosion resistance in accordance with DIN EN ISO 8227 depending on the substrate:

  • Zinc, blue passivated, GC TOP 189 WR > 168 h RR > 480 h
  • Zinc-nickel, transparent passivated, GC TOP 189 WR > 200 h RR > 1000 h

Other GC Top sealants