Sap ? leeching out of unfinished moulding

[Nearlygotitright]

I use quite a lot of unfinished obeche, mostly without any problems, but on each of the last two frames I've had rusty red spots in one or two places, quite small but they show up like hell on a white frame. I usually just give the moulding a couple of coats of emulsion followed by some liming wax to give a soft shine. It seems as though it is sap in the wood. I've tried sanding them out, digging them out, covering them with knotting, but without success. Can anyone suggest a sealer that would eliminate this problem?

[mark@bhf]

normal knotting solution is not great at the best of times. Having spoken to the leader of the opposition (the wife) she assures me that the best course of action is to use a matt finish clear yacht varnish, then give a light sand once dry without breaking the surface, and then a coat of 'dulux interior emulsion' BUT get the ENDURANCE type with the yellow logo at the bottom of the tin. Hasa worked for me on a house full of new skirting boards & solid wood doors. The emulsion must be DULUX, as crown or some home brand are not up to the job. Not biased, just honest. remember to allow at least 10mm extra past the knot with the varnish, as the 'sap' can bleed.

regards

Mark.

[framemaker]

I use a fair amount of obeche, and have had this problem a few times, usually it is only a couple of very small spots which are dark red/brown/black. On a white or limed finish it is probably pretty hard to cover up. Maybe with a solid paint finish you could do as Mark suggests, or maybe a good oil based primer/undercoat or stain block paint would stop the spots bleeding through. Seems like alot of trouble to go through to me though.

[prospero]

I think I have only had this happen once on Obeche. Fortunately it was a mottled finish so easy to fix.

On Pine I tend to drill out any knots and fill them. Sometimes I just give them a dab of Shellac, which is basically what knotting sealer is. But the stuff that's sold as Shellac tends to be thicker than the sealer. On fresh sawn Pine I give the whole surface a coat of Shellac.

Never had any sap bleed through at any rate.

[Nearlygotitright]

Thanks to Prospero and Mark, good ideas there, should hopefully solve the problem in the future. Been away for a few days, hence the delayed response.

Tom