Repainting window boards

[stealthwolf]

Now we’ve had new double glazing installed, the existing window boards look naff.

I’ve started sanding down using 80/120 grit. There’s at least five different coloured layers before I reach bare wood. There are “hot spots” where the I’m down to bare wood and surrounding areas still have the very top layer of paint. Is this down to uneven wood/uneven paint layers or my sanding (using an orbital sander)?

I will go for a satinwood finish. Is it worth sanding the primer in 240 grit? What about the first layer of satin? Aim is for a smooth finish, without brush strokes visible.

 

[opps]

If it is MDF, the hot spots may be where the MDF has previously swollen.

Brush strokes are largely a function of brush and technique. I'd recommend a Purdy Elite Sprig and if waterbased paint, add some floetrol, if oil based, add some Owatrol oil.

 

[stealthwolf]

If it is MDF, the hot spots may be where the MDF has previously swollen.

Not MDF.

In addition, the wood is cupping/cupped - I didn’t notice until I got out my multitool to sand the edges. The wood dips in the middle.

I’m struggling to sand. 3 sessions of 20 minutes of sanding and I haven’t done half the window board. Either the sand paper is rubbish, my tools are rubbish, or there’s something else making it more difficult.

I’m loathe to use a paint stripper lest it damage the UPVC windows.

 

[opps]

Not MDF.

In addition, the wood is cupping/cupped - I didn’t notice until I got out my multitool to sand the edges. The wood dips in the middle.

I’m struggling to sand. 3 sessions of 20 minutes of sanding and I haven’t done half the window board. Either the sand paper is rubbish, my tools are rubbish, or there’s something else making it more difficult.

I’m loathe to use a paint stripper lest it damage the UPVC windows.

You can't do much about the cupping other than using loads of 2 pack filler.

Are you planning to sand all of the paint off? I normally treat existing paint as "filler" to be smoothed out.

I suspect that part of your problem is that oscillating saws are very inefficient sanders. The pad arcs at about 3 degrees. I own one of the only linear sanders on the market. I rarely ever use it because it is so slow. I do use my oscillating saw with custom made attachments for sanding in very hard to reach areas but not very often because it is so slow compared to my orbital and random orbital sanders.