Sanding glossy doorframes before repainting - wet/dry? and what grit?

[alligatorlizard]

Any tips re. sanding glossy doorframes before repainting? Main questions are:

1) Will wet sanding work here? And if so, what's the best method, e.g. cold vs warm water, and does it help to add some fairy liquid?
2) What grit should I use?
3) How much do I need to sand? Is it OK to just lightly sand until I get a rough surface - e.g. don't need to completely strip the old paint, right?

In the first instance I'll be repainting with Johnstone's "My Colour Luxurious Durable Matt" (cupboard door and it's frame), and for the remainder of the doorframes will be using Johnstone's Trade "Aqua Guard" (primer plus satin topcoat) - just mentioning this in case it makes any difference to sanding requirements.

Thanks!

 

[Wayners]

I dustless sand with 120grade.
I have wet and dry paper with warm water. Cold will make your hands cold.
No soap
120 grade if rough. 180 grade if not bad.
You just need to get a key for paint so its just a rub over.

Also important to clean prior to undercoat. There are a number of cleaners on the market. Zinsser make one. You can also use meths if grubby.