Thick (>200 nm) brushes sometimes developed a hazy, rough finish (see SI). It was not possible to remove this haze by rinsing or ultrasonic cleaning without also completely degrafting the brush. However, using a more resilient APTES-PGMA-TRIS grafting layer instead of APTES permitted the removal of the haze without degrafting the brush. Although we were not able to ascertain the exact mechanism behind the emergence of the surface roughness, we postulate that it is caused by non-grafted polymer that entangles with the brush at sufficiently high chain lengths. Moreover, we found that the issue could be prevented by more thoroughly cleaning the wafers after initiator coupling by ultrasonic cleaning for 5 min in an ethanol/water mixture. This suggests that surplus physisorbed BiBB that is present on the wafers when they are not adequately cleaned is the source of non-grafted polymer.