Spot staining on gloss

[bikeit]

I got all the architrave replaced in the hall stairs and landing with red wood about a year ago, all the nail holes and dents in the architrave were filled in with Polycell fine surface filler sanded down primed, under coated and glossed with Dulux trade paints, but where all the nail holes and dents in the wood were filled it is starting to show through the topcoat as yellow spots all over the wood, what did i do wrong or how could this have happened?

 

[misterhelpful]

This is probably not the filler or nails showing through the paint but the resin from the knots in the wood bleeding through. You should have used a knotting solution on them before applying any paint.

Rather than rubbing back to the bare surface to do this now, you can solve the problem by using a stain blocking primer/undercoat before re-glossing. Zinsser make a good one and Ronseal have recently brought a new one out too but both are quite expensive.

 

[dcdec]

Bit of a shame to paint it. I can only think that its rust spots, did you use an acrylic primer? Someone else might have other ideas as i've never come across redwood, not knowingly anyway. I don't know what this timber is like for knots, it could be that but they usually show darker than yellow. I dont think its premature yellowing of gloss as this would be more uniform through the whole coating
Solution would be to give a coat or two of zinsser coverstain regardless of the cause and then u/c and gloss

 

[bikeit]

I did use knotting solution, am i better to sand down only the spots and put some Zinsser onto the spots let dry lightly sand down all the architrave then re undercoat and finish off with a coat of white gloss

 

[hihosilver]

The zinsser guy is right, you can spot prime with the shellac based bin primer,
this is better than the water based one, perhaps you knotted them, and then rubbed them down way too much?