A/C Evaporator Housing

[tanda62]

Took apart my A/C Evaporator Housing so I can clean and paint it in preparation for reinstalling.  Discovered this pattern of a rubberized insulation on the bottom with a clear channel leading to the drain.  I dripped some water on the area and it beads up pretty well on the insulation and eventually makes it way to the clear area and the drain. 

Just wondering if this is factory or did someone along the way modify this along the way and I should remove it.

Thanks for any assistance, Tom

I will remove and replace the Dum Dum along the edge used to seal the unit when back together.