Thats the problem, mistcoating with silk, then applying matt, as matt wont go over silk without some hard sanding, but yet Silk will go over Matt no problem.

I'm with Fordy, re the undercoat route, just buy some cheapo oilbased undercoat, mix with white spirt, dont apply it on the wall straight from the can, 1, its far too thick, and you will get horrible brush/roller effects/plus you will labour.
So add some white spirit, so its like thick runny cream, not thin where its running down the wall and your forever wiping the runs lol.
Then when dry, apply a coat of your diamond, ( did you thin the first coat of diamond down), but thin it down by about 10%, you wont lose any of the coverage, but you will get a far better finish, then do another coat, and again thin by 10% water, you will then have a lovely smooth wall.

BTW, use a medium pile roller sleeve for that nice flattish look.

Please come back and let us know how you get on.

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I would rather want something I dont have, that have something I dont want

Stay well clear of Light and Space. It's a waste of the extra money and it doesn't make that much difference, despite what it says in the marketing blurb.

Good luck and don't feel bad. "We all make mistakes" said the dalek climbing off the dustbin.

Hi Guys, I gave the walls a thin coat yesterday. Initially small air bubbles kept appearing around the cracks but it dried fine. I’ve just finished the second coat, and although there were still a few small holes (like pin-pricks) that it wouldn’t cover, it looks brilliant.

There is just one problem, I couldn’t get a colour chart for the Dulux Diamond so I looked online and ‘Amber Wave’ looked close to the ‘Amber Spirit’ she bought in the light and space. When I opened the tin yesterday, it’s more of a peach colour and nothing like the original they wanted (or the colour I saw online).

Can the Dulux Diamond only be painted over with silk now? I’ve told her that may be the case, which she’s fine with, but my brother-in-law prefers the other colour and wants me to go over it with the leftover light and space.

Thanks for all the help; it has really worked a treat.