repainting old windows

[dotto]

Hi guys.
I need to repaint my wooden windows as paint is coming off and i have no budget to replace them with upvs. Do i need to prime them followed by undercoat and two glossy topcoats? Do i need to buy primer for external wood? Do i need to buy an oil based primer and undercoat or waterbased will do the job just as well followed by two topcoats of oil based glossy paint? What happens if i just give them a coat of primer followed by 2 topcoats and no undercoat?
I would appreciate if you could give me as much infos as possible. Thank you in advance

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[misterhelpful]

Any bare wood should be sanded to remove weathering.
Repair damage with a suitable wood filler and allow to dry before sanding smooth.
Thoroughly rub down all surfaces with fine sandpaper to provide a key for new paint to stick to.
Only the bare timber really needs priming, but it is wise to use a combined primer/ undercoat over the whole area paying attention to the bare wood in particular.
Once dry, again sand lightly, dust off and wipe with a damp cloth.
You can now apply your top coat/s. You can get away with a one coat gloss but two coats are always better for lasting protection.
Oil based undercoats are traditionally better but water based ones are now just as adequate. Stick with an oil based topcoat though.
Hope this helps.

 

[dotto]

thank you very much for your help. BTW, what is the reason for applying undercoat if you already apply a primer? If it's for creating a key for top coats, you can create it by lightly sand it down which is what you would do in any case. Thank you for clarifying this point and for your time.

 

[misterhelpful]

Primer generally seals the wood before the undercoat is applied, and a seperate undercoat gives a better surface and base colour for the topcoat. As I said, it is worth just using an all in one primer/undercoat as this effectively does the two jobs in half the time.

Also, I forgot to mention to treat any knots in the bare wood with knotting solution before applying any paint. However, if you are using a Zinsser primer/undercoat then it is usually not required.