I would like to paint over walls which have Dulux Silk Emulsion with Dulux Matt Emulsion. Would you advise I paint Matt over silk?
I also wanted to know if there was any issues with painting Matt paint onto a wall which has silk emulsion? Do I need to do any prep on the walls beforehand? I’ve read online some people have had issues with Matt paint cracking when painting onto a silk emulsion wall and others have said they have had no issues with this at all.
You’ll find it easier to use matt paint and it usually produces a better result. I would only use silk if there is a likelihood that you’ll need to wipe any marks off the wall. For example, in a kitchen or, maybe, a room where kids play?
With silk you can also have a problem painting large areas because it is drying while you paint and if you are not quick enough you can get unsightly marks across the wall where you have a double thickness of paint on the drying edge. This is what we refer to as ‘flashing’ and it can be a problem, even for professional painters. You do not get this effect with matt paint.
The only reason I can think why the paint would be ‘cracking’ is if the surface was contaminated with grease or residue from old wallpaper paste? [some relevant questions here…]
Since your walls are not wallpapered we can rule out wallpaper paste. As for grease, it is always a good idea to wash-down the walls first to remove any traces of grease or other contamination that can build up other the years from finger marks and such. You should use a mild sugar soap solution and then rinse with clean warm water.
If you don’t want the extra expense of sugar soap, just clean warm water is preferable to household cleaners such as washing up liquid which can leave a residue behind causing further problems.
That said, for a normal domestic situation, cleaning the walls in such a way is possibly excessive but does help ensure you get the best result.
Also, I should add, you can always start with a the smallest area first; then let it dry and check the result before going any further.