foil on triblend

[IntegriTees]

foiled my first triblend today.  went with a pfp of the virus adhesive and then flashed it and stacked it for foil.  First press of the foil came out great, but the shirt had some "shrinkage" at the bottom of where the heat press ended. 
350 degrees for 15 secs

What do i need to do to remedy this?

[Audifox]

When I'm working on sensitive fabrics I use the Stahl's  silicone pad. Helps with marking on fabrics. Should help with your "shrinkage" issue on the tri blends.

https://www.stahls.com/heat-press-flexible-application-pad

 Put it below your image you're pressing and it won't leave marks from the heat press.