i guess the answer is here. https://www.ephere.com/plugins/autodesk/max/lucid/docs/1/Collision_objects.html

i had no internet last weekend to read up on this :-D

it turned out to be none of the suggested. i ran about a 100 tests last night. it looks like it has to do with particle size bellow 1.0cm. but i'm still going through all the cloth settings and how they relate to eachother. collision tests are next i guess