A question I’ve been having all through this thread:
MEK flashes almost immediately, so is good for a quick bond and doesn’t have time to leave glue “shadows” or “witness marks” on the exposed surface of the styrene which can be visible after you apply paint.
Testors does tend to leave such marks, as its slower drying time leaves more time for the wet glue to attack or craze the plastic.
This typically occurs when I’m holding two pieces of styrene together, and using a small paint brush to touch the joint, so the glue will run along the joint by capillary action.
Where the brush touched the work, I can get the marks I mentioned if using Testors. The marks aren’t visible using MEK.
However, if I’m applying glue to both surfaces and then pressing the parts together, MEK will invariably have dried before I can get the parts joined.
So in that sort of situation I use Testors.
I also feel that a Testors joint is stronger than an MEK joint, because the glue has more time to impregrate the plastic, creating a better, deeper weld.
So each has its place.
My glue stand has a bottle of each and I select the one I feel most appropriate for the job I’m doing.