I normally git those kind of areas with Zinsser Bin (because it dries within minutes). I guess you could use the Guardz though. Either way, If you have used a dark emulsion you will need at least two coats of emulsion.
Need to be careful, because sometimes you can see the spot paint under the top coat as they have different textures, or the way they were applied was different.
Probably would have been best priming the walls with a contract white emulsion 2 or 3 times to fill the porosity of the different surfaces and then painting the top coat.
Oops is a pro though (I believe) and will be better placed to advise
Would zinsser123 also work on lining paper?
You are correct about the risk of different paints affecting the texture of the lining paper. In this case the OP has already used emulsion over the lining paper which means that the fibres in the paper are pretty much "uniform" and fairly flat. I would never use BIN or oil based undercoat as a spot primer on bare lining paper because the fibres would stick up and in the absence of sanding, would be obvious after the emulsion was applied.
Ideally one would apply the BIN (/etc) with a rad roller to maintain a constant texture. When it comes down to it, the filled areas will be flatter than the paper, so you either do a semi dry roll with the mini roller or stipple it with a brush when applying the emulsion.
So on bare filled lining paper the best option is to paint diluted emulsion to cover the filler rather than applying any zinserr at all?
We seem to be at cross purposes... I suggested using Zinsser where you can see the filler grinning through the emulsion that you have already applied.
If you are using a powder based filler on fresh lining paper then, yes, slightly dilute the emulsion before applying the Zinsser. If using something like RedDevil OneTime or Toupret RedLite, there is no need to dilute the emulsion. Personally, I prefer to do any filling after the first coat of full fat paint.
Apologies for causing confusion.
What I meant was if I apply lining paper and then fill, what precaution do I need to take so that the filler does not show the first emulsion coat.
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