BIN ok for damp stain on wall?

[Mattatooi]

Just put mist coat on wall, and kind of forgot about these water/damp stains;

This is old pic before prepping wall;


So yea just want to know if its ok to use Zinseer BIN on this area. ( I have half a can so dont need to buy) I take it I only need to cover the stain areas and not the whole wall!?

Shall I just give a light sand and apply zinseer or can i just chuck it on? Then once dry do I put same mist coat ratio on top or shall i not water down at all? Using dulux trade vinyl matt.

Pics of current wall. Hard to see in picture;

 

[Mattatooi]

I should note that when we moved in july 2014, we got all the windows and doors on the outside fixed around sides with a cement like stuff. Cant think of the name. But it was all done as it came up in house report and builder friend saw it too. Here is pic of what I mean;



The stain looks like an old damp stain from before. Nothing has changed on the wall, ie nothing got bigger or anything same consistent stain. And it doesnt feel damp or anything. I am 99.9% sure its just a stain from past.

 

[misterhelpful]

You can use B-I-N to cover the water stains but you need to be aware that, because it is shellac based, it can often 'flash' through the final coat if you just apply over the stained area - meaning you will see what appears to be a patch on the wall from certain angles. It usually disappears after a couple of topcoats but you need to allow longer than usual before re-coating the area because the emulsion doesn't cure as quickly on top of B-I-N as it does on the water based stain blocks. For this reason, when just applying a patch, I would prefer 1-2-3, as trying to paint a whole wall with B-I-N can be tricky because it dries so quickly. That said, there is no reason not to use B-I-N, other than that I have just mentioned. No mist coat is needed on top of it.

 

[Mattatooi]

Yeah I went ahead, and i put some mist coat on top anyway as I was painting over more areas I filled after painting the mist coat on walls. I also gave it a little rough with some sandpaper as someone else said it helps as it can have a shinyier finish on the shellac. Thing is, the area that has been done is not in a really noticeable area.