How to spreading butyl sealant well onto alu.spacer？

There are two sealant in insulating glass production. 

1. The primary sealant-Butyl/PIB sealant.
2. The secondary sealant-silicone,polysulfide.

So now we are talking about the primary sealant–butyl.  

• Where should you spread the butyl onto the aluminum spacer?       In the middle of the spacer bar side. 

• What is the best volume for butyl spreading?    usually 0.3g/m. 

• The butyl sealant width before press: ≥3mm.

• The butyl sealant width and thickness after pressing.   Width: 4-4.5mm.  Thickness:0.3-0.5mm. 

See the below picture for instruction.