Florin Nutu
New member
This is the second time I encountered this within the last couple of months. I got a yellowish brown stain pop up after I apply my house wash mix. The first time it popped up only on the vinyl frame edges of windows. Second time was on painted hardiplank siding. It does not come off with scrubbing or stronger mix. Luckily I tried citric and it disapeared. So it has to be a reaction to the PH. Anybody encounter this or know what it is. Sorry no picks.