Knots and water based paint/primer/undercoat

[P3RD]

Hi all,

I need to seal a load knots in some architrave and doors + lining and I’m not sure how to approach it.

I only want to use water based paints, primers, undercoats and finished. I already have some dulux trade quick dry wood primer undercoat 2in1 (water based). I plan to finish the architrave/doors in white gloss (water based).

I’ve done some searching and found people use Zinsser BIN. Can I use BIN on the knots and then paint the water based primer/undercoat (couldn’t find a clear answer on this) or can I use a white knotting solution?

My concern is that the BIN doesn’t say you can paint over it with water based paint, it says any oil or latex paint and the knotting solutions I have seen say not to be used under water based paint.

Note: all timber is new or bare

Hope someone can advise.

 

[opps]

Latex paint and waterbased paints are (generally) interchangeable terms.

Most knotting solutions are shellac based (BIN is pigmented shellac).

I have no idea why some of them have an issue with waterbased paints. See the following, it recommends a light sand before using waterbased paint.

https://www.decoratingdirect.co.uk/viewprod/p/PATENT_SHELLAC_KNOTTING_SOLUTION/

 

[P3RD]

Thanks opps.

I have already come across that page, that product doesn't give me any confidence. Any other white knotting solution I have seen state not to be used under water based paint, what make this so special. If only there was more info on the site.

 

[OchAye]

How about checking BIN's own data sheet here: http://www.zinsseruk.com/core/wp-content/uploads/2016/12/B-I-N.pdf See the Recommended Uses, it can be used on walls, ceilings etc., including the sealing of unpainted plaster based materials. All these surfaces are normally coated with water based paints, including after BIN. Note what Opps said about light sanding.

It is not suitable for exterior use other than spot priming.

 

[opps]

The newest kid on the shellac-block is Blockade by Smith & Rodgers (based in Scotland).

They state that it- Can be used as a base for both water-based and oil-based paints.

They sent me a free sample tin a while ago. IMO is as good as BIN. I haven't used enough of it to determine if it is actually better than BIN but I have been happy with it thus far.

BTW, purchase some household ammonia for brush cleaning when working with shellac. It is alkaline and breaks down the shellac deposits on the brush. Smelly but effective. The ammonia evaporates over night and the waste liquid is "safe" to pour down the sink without leaving any residue in the sink. The alternative is to use meths (or other alcohols) but they simply thin the shellac. Or just buy throw away brushes.

Apropos the dulux acrylic primer. It can be a pig to sand. It has a tendency to clog the sand paper. You might want to consider applying Leyland acrylic primer first. It is a dream to sand back but pants at obliterating colours. It is also extremely cheap. Once any fluffy timber or grain has been sanded you can then use your Dulux primer.

FWIW if you find it difficult to get the waterbased topcoats to flow, you can use Floetrol paint additive or XIM-Bonder.

 

[P3RD]

...it can be used on walls, ceilings etc., including the sealing of unpainted plaster based materials. All these surfaces are normally coated with water based paints, including after BIN. Note what Opps said about light sanding.

It is not suitable for exterior use other than spot priming.

Didn’t think of it that way.

Thanks.

 

[P3RD]

The newest kid on the shellac-block is Blockade by Smith & Rodgers (based in Scotland).

They state that it- Can be used as a base for both water-based and oil-based paints.

They sent me a free sample tin a while ago. IMO is as good as BIN. I haven't used enough of it to determine if it is actually better than BIN but I have been happy with it thus far.

BTW, purchase some household ammonia for brush cleaning when working with shellac. It is alkaline and breaks down the shellac deposits on the brush. Smelly but effective. The ammonia evaporates over night and the waste liquid is "safe" to pour down the sink without leaving any residue in the sink. The alternative is to use meths (or other alcohols) but they simply thin the shellac. Or just buy throw away brushes.

Apropos the dulux acrylic primer. It can be a pig to sand. It has a tendency to clog the sand paper. You might want to consider applying Leyland acrylic primer first. It is a dream to sand back but pants at obliterating colours. It is also extremely cheap. Once any fluffy timber or grain has been sanded you can then use your Dulux primer.

FWIW if you find it difficult to get the waterbased topcoats to flow, you can use Floetrol paint additive or XIM-Bonder.

Thanks for all the info.

Undercoat/primer already done, didn’t have any issues with sandpaper clogging, but at the same time I got sandpaper lying everywhere so I just use the piece in the room I’m in.

I used meth spirit for cleaning the bin and then warm soapy water with out any issue, but that’s what I had to hand.

I will look into the additives.