How to repair for patchy windowsill with plaster?

trudyh

Hi there I stripped back and sanded my window sill, but couldn't get it to even levels (ie some areas paint stripped back to whag looks like 2 colours ago). I used filler to patch the lower levels, sanded and primed, but it clearly wasn't the right thing to do.

From other questions it seems a skim coat would be an easier remedy (I was wary that the older layers of paint might have lead in them, so am not keen to sand deeply again).

Questions:

1. Sand the primer off again first? Or can I skim coat over the primer?
2. I've got Gyprock multi purpose joint compound from other jobs. Could I use that or do I need to buy the topping compound? (They seem to come in large quantities that you end up with left overs that never get used).

Thanks

Trudy

JacobZ

Welcome to the Bunnings Workshop community @trudyh. It is fantastic to have you with us.

If you have concerns about lead paint being present, I think the best thing you could right now is stop and have it tested. If there is lead paint present, I'd suggest it is probably best that you stop work and have a professional assist.

With that being said, what you did initially was the correct thing to do, you just might have applied your filler a bit too thick initially and as you were being cautious with the sanding, didn't sand the filler enough to get it flush.

From here, what I'd suggest doing, after you've had it tested for lead paint, is give the slightly high patches (green box) a bit more sanding, and filling those paint chips (red arrows), doing your best to fill them flush with the paint around them.

All-purpose compound is designed to have an intermediate level of strength and sandability between base coat (hard/very difficult to sand) and topping compound (soft/easy to sand). It can be used, but it will be tougher to sand than a topping compound, which in this situation is likely part of why you struggled the first time.

For any further skim coating, I'd say it is worth using a softer compound than all-purpose. If you didn't want to have a lot of wastage, there are smaller options that can be used such as -

• https://www.bunnings.com.au/uni-pro-500g-smooth-coat-skim-filler-500g_p1560087
• https://www.bunnings.com.au/poly-510g-interior-skim-coat-filler-510g_p1210370
• https://www.bunnings.com.au/sika-250ml-white-filler-101-fine-surface-filler_p1661254

With the paint chips, apply enough to adequately fill the hole, then angle your applicator and strike over the patch to remove any excess. With this kind of filling, you don't want it to sit proud of the paint even slightly.

Once dry, give it a light sand with a fine sanding sponge, brush off any dust, then prime and paint.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob