Advice - Issues with painting wood

[Mattatooi]

Hi

I am painting my internal window sills. I had sanded them with 80 sandpaper and rubbed them down. I have applied FOUR coats of Primer/undercoat and it is still going yellow. (I am using homebase wood primer/undercoat)

Here is picture of one of the other window sills in the house;

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• Mattatooi
• 17 Oct 2014
• 1

Here is picture of window sill i have painted with undercoat 4 times;

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• Mattatooi
• 17 Oct 2014
• 1

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• Mattatooi
• 17 Oct 2014
• 1

(Sorry It might be a little difficult to see in photos)

I thought by 3rd coat that it would go away, but within seconds of painting it starts going yellow again. I am new to painting but thought I did correct thing. Can anyone help me here?

I am also painting fire surround. This is looking much better. I have just applied 3rd coat and its looking good but I do have a few patches of yellow staining again;


Before;

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• Mattatooi
• 7 Aug 2014
• 2

After;

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• Mattatooi
• 17 Oct 2014
• 1

- Some yellow stains on side near top

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• Mattatooi
• 17 Oct 2014
• 1

Inside top right area some stains

Once again I sanded this all down. Should I be worried about these little patches, as I will probably be applying 2 coats of finish? The fire surround will be finished in a cream/ivory type colour (undecided yet!).

The window sills I want to be white!

 

[Justin Passing]

It's common for water soluble stains to come through water based paint. There's all manner of stain sealers, even in spray cans, but ordinary, traditional, oil based undercoat paint will usually stop it in its tracks.
Two thin coats would be good otherwise you can get "spotting" if a pinprick isn't covered. A little white spirit thins the paint a lot and makes go on fast and dry much quicker.

 

[emilybronte]

Are you using water based paint or oilbased?

 

[misterhelpful]

I'm assuming you are using water based paint as that is what quick drying, combined, primer/undercoats generally are.
If so, then you will need to seal the surfaces to stop any resins and/or existing woodstain bleeding through. The sills appear to be hardwood which benefit from either Aluminium Wood Primer or Zinsser B-I-N as a sealer. If you are going with an oil based system you could use either, but if you are using water based, you would be better served by the B-I-N.

The same methods are applicable for the fire surround, but if you had used B-I-N, or any another high grip primer sealer, you wouldn't really have needed to sand it first.

 

[Mattatooi]

Using water based. Was thinking BIN might be the answer, very expensive mind you. Should I lightly sand the sills again before putting BIN on, considering there is 4 coats of water based undercoat on it?

Thanks for replies

 

[Mattatooi]

Just wanna add. Later on down the line im considering painting my staircase rails which are a similar colour of wood. Would I be able to just use this B-I-N stuff on it, even without sanding? Just wanna at least get good use if I am buying this stuff, as it is not cheap!

 

[misterhelpful]

Yes, you should be able to put B-I-N on the rails directly unless they are waxed. Be aware that it can be very tricky to work with due to it's quick drying time but, if you work methodically, you should be able to keep a wet edge to work with.

You would be wise to give the sills a light sand, if only to remove any nibs or brushmarks, then dust off and apply it.