Sealing timber knots.

cosmowillie53 wrote: »

I have one new door to paint (white) which has quite a few knots.
Can I use a mixture of clear varnsh and white spirit to do the job and if so would a 50/50 mix be ok.
I was going to just dab the knots with the mixture.
Thanks for any info.

Are you sure the knots are not already sealed? Manufacturers often use clear knotting sealant. If you are unsure, why don't you just buy a small bottle of knotting solution from your local hardware store? Much easier and more reliable than trying to make up your own solution, that probably wouldn't work anyway!

mikehn wrote: »

Any suggestions for knots that have been painted over without treatment and are now showing through white gloss.
Thanks

The only answer to that is to remove the gloss paint and any undercoat or primer -- I would use a hot air gun or a paint remover such as Nitromors. Sanding it off won't work as the sandpaper will simply clog immediately with the resin from the knots. Once cleared off, apply the knotting solution. Unfortunately you will need to strip the whole surface of whatever is painted, since you won't be able to just repaint over the treated knows without it showing.

If you go for Nitromors, it is highly caustic, so wear rubber gloves and eye protection, and don't let it anywhere near plastic or linoleum. It also gives off irritating fumes, so plenty of ventilation is essential.

All of this sounds like a big job, but it isn't really. Say half an hour to clear the paint off of a door, half an hour of sanding (avoiding the knots after they've been treated), and then another hour or two of priming, undercoating, and painting. If it's indoors, then acrylic paints (water based) dry very quickly without fumes, and they are available as gloss, matt, and varnish.

mikehn wrote: »

Thanks Art6, I was kinda hoping that there would be a magic solution in a bottle or tin but it looks like a bit of elbow grease. I will be following your suggestions, great comprehensive reply.

No offence to Art but that suggestion is way overkill. Look at post 3. Just apply directly over the bleed marks from the knots, 2 coats if necessary ( drys quickly ) and then repaint with whatever's there at present, gloss or satin-wood I guess. Thats it, job done.

cosmowillie53 wrote: »

Do you mean to remove paint from over the knots (by whatever means ) Apply solution to the knots & allow to dry. Apply finish paint just over knots or repaint the whole door.
Thanks.

If the knot is smooth, just apply directly over the affected area with a regular brush. You don't have to remove anything. Leave to dry, and then apply the sealer again. Seeing as you have already painted the doors, you might well be able to apply the final coat just to the affected areas and see if the end result is satisfactory. Worst case, just give the door(s) a full re-coat.