VW T4 rear screen problem

[Guest dazzer]

Just need a bit of advice. I have recently been doing a lot of T4 rear screens. All to date have been easy and looked great with happy customers. I have one van that I had in a few weeks ago to do just the rear screen that had areas on the heater lines that just wouldnt stay down even with heat. The owner had been on holiday but I had the van back today and removed the tint and re did it and in exactly the same areas it did it again. The van has recently had a full respray which included all the windows being removed and re fitted. Could this problem be some contamination on the glass that obviously isnt coming off when I clean it. 

Method I am using is dry shrink the wet test the final trim then install 

This one van is doing my head in now 

 

[Guest hampshirewindowtinting]

Shrink it.

 

Cut it to size.

 

Then run the heat gun slowly along the bottom and top edges.

 

If any fingers appear, you haven't shrunk it properly and it will lift on the heater lines. 

 

It seems to me that it lifts on the heater lines because its trying to form fingers that haven't been completely shrunk out.

 

Use plenty of pressure on scouring the heater lines prior to installation.

 

Should then stick down fine. 

 

I had this trouble with T4's and T5's but not any more