Painters:How to remove this stain from my ceiling?

beachboy61, Oct 3, 1:32am
I painted the ceiling of my existing shower 2 weeks ago with two coats of a (4 in 1 oil based sealer, primer undercoat) then one coat of an oil based semi gloss enamel.
About a week later this stain appeared directly above the shower head on the ceiling.
https://trademe.tmcdn.co.nz/photoserver/full/652820300.jpg

It looks like mould, but it won't come off with Simple Green or other cleaners; it seems to be embedded into the paint and I think is caused by hot steam on the painted surface.
We waited 4 days after painting before using the shower
I think I have to seal it with something else?
I'd prefer not to have to remove the existing paint as some is on a cove which would make paint removal difficult.
docsportello, Oct 3, 2:42am
Was it there before you painted? Are you sure it isn't midges that flew in the window and stuck to it?
beachboy61, Oct 3, 4:34am
No, it certainly wasn't there before I painted and no there not midges.
iluvmuse, Oct 3, 6:12am
If it's mould I would re-undercoat the whole ceiling and topcoat with a mould inbitive paint like Mouldshield http://www.dulux.co.nz/products/dulux-interior-products/walls/product-detail?product=14685
Or you could use it to patch the problem area and touch-up afterwards with your enamel. It's acrylic so needs an undercoat to stick to your oil based enamel
johotech, Oct 3, 6:19am
What prep did you do to the ceiling before you put the first coat of sealer on?
beachboy61, Oct 3, 7:02am
johotech:There were to small flaky areas that I sanded and I then sanded the whole area and cleaned the area with a dry cloth.

Ilvmuse: I am a fan of oil based paints in the bathroom
johotech, Oct 3, 8:00am
I'm a big fan of washing down before painting. Especially bathroom ceilings. There could have been mould that wasn't visible.

Oil based paints actually contain more organic ingredients than water-based paints and are more likely to grow mould if the surface hasn't been cleaned properly.
happychappy50, Oct 3, 8:22am
With all this wet weather using an oil based paint it may not have cured sufficiently then the shower starts up again combined with steam,hence the pinholes,let it cure then pole sand & hit with Bin shellac based sealer,then a coat of Bin 123 then use an acrylic ceiling paint with a mould inhibitor added should fix your problem
wine-o-clock, Mar 15, 9:10am
How come you only waited 4 days? Paint would have not cured by then

from google
For a paint to be considered dry, enough solvents must evaporate so it feels dry to the touch. Paint doesn't cure, or reach maximum hardness, until days after the paint is dry. Oil-based paints cure faster (in about 7 days) than latex paints (in about 30 days).