Silly Painting Mistake

DevCoder

Ok, so some silly person who will remain nameless thought painting oil based gloss over eggshell gloss without an undercoat would be ok.

Bear in mind, this is two hallways of skirting and architraves comprising of 5 doors.

So of course, the gloss just peels off at the slightest knock.

Ive begun stripping it by hand, using my fingernails I can get a good strip of it peeling away from the underlying eggshell.

You can call me an idiot, but only if you can advise on

1. I assume I need to strip all the oil based gloss off as the new paint needs a sound layer? What about where the gloss doesn't come off (top of skirting for example, the oil gloss seems to have found enough of a key to stick to this), can I just sand this down for a key?
2. Do I do this with my fingernails, is there a better method?
3. Could a liquid sandpaper be used? Or is this going to create more work then just stripping it off by hand.
4. Once Ive completed the above, can I just sand down to give the undercoat a key, do 1 or 2 layers of undercoat and then a layer of gloss?

Any other tips to shorten the preparation work, my fingernails are not the best paint removers but scrapers are too sharp so don't pull the paint away at an angle.

Crinkmeister

Did you sand/clean the eggshell before glossing it? I'm surprised that the gloss is coming off. I wonder if the eggshell was actually a latex based paint or perhaps not cleaned properly? Best way to remove loose gloss is aluminium oxide abrasive paper P120 or P180 - I wouldn't use the liquid. One undercoat and 1 or 2 topcoats is what you need after keying all the surface.

DevCoder

Thanks Crinkmeister

It was water based eggshell, I cleaned it with sugar soap but didn't sand it to any degree.

Ill avoid the liquid sandpaper as that appears to be just messy.

I can peel large strips of the gloss off, so a few days work and I can remove most of it, Ill the use your suggestion of aluminium oxide paper to get the scraps off and provide a key.

Is there any advantage to doing 2 undercoats as opposed to 1 with an abrasive scratching in-between coats or is that not the right way? Just thinking that I need to avoid painting gloss on top of gloss, but if thats ok then Ill do one coat under and two coats top.

Incidentally, whats the best make/brand of undercoat and gloss?

Ive been recommended Zinnsser undercoat which is pricey but if it gives a good finish then Im not too bothered.

I went with a water based gloss originally due to the yellowing of oils based but water based really does show the brush marks, any advice ?

Crinkmeister

Ok - preparation plan sounds good. Make sure you vacuum up all the dust and then I always go over with a white spirit loaded rag to remove any remaining dust and grease just before applying paint. One undercoat is enough. One or two topcoats, depending on the finish. You can give a light sanding between topcoats with something like P320 grade if you really want, but I tend to skip this step unless there are any bad areas. Gloss will stick well to freshly painted gloss.

I always use Dulux trade paints. Beware if you are using brilliant white gloss - it won't stay brilliant for too long these days and I think the same will be true for any modern paint whatever the brand thanks to restrictions on composition. Never used Zinsser - I believe it's good for covering up dark or stained areas, but probably not necessary in your case. Good luck.