Collide treatment

rather not say

An earlier message I posted about gunk in my home boiler after installing a new cast-iron upright radiator was answered that I may need a collide treatment. Any more information on this would be a big help. Need to find out what it is and if a total amateur can do it.
We have been draining the boiler water whenever it gets dirty, which now seems to be almost every day since we installed that new radiator. The water is no longer black, like after the initial installation, but now there's a brown oily residue that hangs at the top of the sight glass and at the top of the water. Thanks in advance! And thanks to everyone on this extremely helpful site for all your guidance!

[Deleted User]

try skimming the boiler

to get the slime off the waters surface.

rather not say

OK, I'm gonna admit how totally clueless I am - how do I skim the boiler (Burnham make if that matters)...