Repainting glosswork - stripped back & found black base

[Llarius]

I've just started to remove some of the awful glosswork in our house that the previous owners had just painted layer on layer, resulting in the top layer flaking, and the doors not to close properly (and they left drip marks everywhere).

I've just been sanding one door frame and found several layers of white, with a peachy colour beneath that, and then a final black layer below that, before reaching the bare wood. What would the black coat be? Is it just a primer and do I need to be careful? The house is 1930s if that helps.

Also to repainting it all neatly, do I need to fully remove the old layers of paint, or can I sand until I get an even layer, then repainting on top of whatever is left? For instance the frame I've just sanded feels much smoother now even though there is a mix of paint and bare wood. I've been using a sheet sander to do the sanding so I expect it is picking up on any unevenness in the surface. Please don't suggest replacing the frames etc, as this is not possible due to cost! Really tight budget and I need to make do unfortunately.

 

[joe-90]

Replace the door and the frame.

Seriously though, all you need do is to make the old layers smooth then use an oil undercoat and a top coat of your choice. A water based satin is probably the best bet. (Non yellowing and easy to apply).

A belt sander on low speed is best (Lidl £24.99).

 

[Llarius]

Thanks Joe.

Is there a big difference between a belt sander on slow and a sheet sander on high?

Also is nitromoors worth using at all?

 

[joe-90]

Forget Nitromorse.

The reason for a belt sander on low is lower friction - so the belt doesn't clog with melting paint.

Well worth having for many reasons. Can be used to sharpen all sorts of things too.

 

[opps]

whilst belt sanders are useful for sharpening chisels etc they can be difficult to use on anything other than large flat surfaces.

I would recommend a random (disk) orbital sander to complement your (rectangular) orbital sander. The rate of stock removal will be higher than the orbital, lower than the belt but the quality of finish will be higher. I would also suggest that you connect the tools to a vacuum. Henrys and budget vacs will suffice at a push. The dust is likely to contain lead. Tbh your exposure won't be that high but it will help to prolong the sanding paper and save on clearing up.

 

[Llarius]

Cheers guys. I'll look into the other sanders.

 

[JohnD]

the black will be a prewar linseed oil gloss paint. It almost certainly contains lead so you should not be sanding it.

If it was me I would use a hot-air gun to strip it using metal scrapers and a good breathing mask.

you may find that the modern gloss on top of old linseed cracks and crocodiles due to the softness of the old paint.

BTW the chemical strippers like Nitromors had to change their formula recently due to dangerous content and are now very weak.

There are some new poultice strippers which some people say are good.

 

[Llarius]

the black will be a prewar linseed oil gloss paint. It almost certainly contains lead so you should not be sanding it.

If it was me I would use a hot-air gun to strip it using metal scrapers and a good breathing mask.

That's what I was afraid of. I stopped sanding earlier and noticed all the layers above the black gloss would peel off easily. I also noticed that the black gloss although tougher to remove is a thin layer, and did scrape easily, so perhaps this is the way forward. Presumably I could do this with all layers together - about 4 or 5 layers of paint in total I think.

 

[Nige F]

If it was a black gloss it would have a dark grey undercoat and a pink primer under it it`s probably a black woodstain from back in the day possibly shellac.

 

[joe-90]

They used to use a horrible brown varnish that turns to treacle when heated. Can't remember the name. JohnD will know.

 

[JohnD]

nope.

 

[Llarius]

Well I "treated" myself to a heat gun that was half price today and some scrapers. Worked a treat! The frame is now clear of most of the paint and just needs a quick sanding before repainting.

 

[opps]

Whilst I do not want to seem to be understating the problem of lead in paint, most people here will have sanded paint containing lead. As late as the 80s lead was still used in primers.

Stripping back to the wood is very time consuming, especially on areas such as architraves. Whilst an electric heat gun will remove most of the paint it will leave some of the (lead) primer behind. This will require sanding. The surface is likely to be damaged by the scraping process and require filling and yet more sanding. Now you will have to contend with both filler dust and lead dust.

I would still go for a sander with dust extractor (possibly HEPA rated). All you are trying to do is flatten the finish. The need to sand all the way back to the black stuff should be pretty limited.

Alternatively, consider wet sanding, it generates no dust at all.

 

[Llarius]

Going back to the wood has been beneficial, and I haven't actually cated a need to fill any patches. My sander does have a dust extraction system with attached bag etc and I have a face mask that I picked up when I got the heat gun too.

 

[joe-90]

It doesn't make any sense to me. You are taking paint off to put it back on again. Crazy. Simply use the existing paint as a primer and simply sand smooth - then undercoat and topcoat. You'll get a much better finish that way.