Preparing window-sill ahead of painting

[curium]

Hi

I need to prepare this window-sill in order to get a smooth finish (will likely be using dulux diamond eggshell since I will have to buy some for the bathroom ceiling).

I was going to post in woodwork but figured it is a decorating problem.

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My thinking is to lightly sand. Use woodfiller for the depressions and then sand for a smooth finish before applying my paint.

It's a 1930s property so I was concerned about lead paint. I've no idea if this is likely to be the original sill. Any advice gratefully received.

 

[blup]

P120 to give a key to the paint you're applying.

Is the depression due to a build up of paint, or rotten/removed wood?

Blup

 

[curium]

P120 to give a key to the paint you're applying.

Is the depression due to a build up of paint, or rotten/removed wood?

Blup

I'm not completely sure.

The crack on the right looks compatible with a normal split in a piece of timber while the depression in the centre looks more like where paint has peeled away unevenly.

I was hoping for some wisdom from the crowds to shed light on the cause and the best way forwards.

 

[sparkwright]

Yes, it looks like some paint has peeled off at some stage, and someone has painted over it.

That dip needs sanding so you can feather out that nasty edge so it's less obvious.

Before you do, give that dip a bit of a scrape, in case there is more loose or peeling paint.

You could also fill over that dip, and sand it, to remove all trace of it.

Fill all the gaps and splits before you start painting.

(You've already said all this, so you know what you're doing.)