Taking shelves down temporarily - replace rawl plugs?

[Anticyclone]

I'm taking down some shelves to redecorate a room.

Should I replace the rawl plugs before I put them back up? I put them up about 4 years ago.

I think you mean Plasplugs.

No need to take them out, and it will tend to crumble the wall if you do.

However, if any are loose and fall out, clean out all dust from the hole, with a vac or water spray, inject no-more-nails or cheaper own brand deep into the hole, press a new plasplug in and leave the glue to set. When hard it will give a secure fixing because the plug will be tight in the hole.

Would that work with fixing shelves to a crumbly wall? My current plan was to drill 6 mm holes and use 7mm plugs, opening out to 6.5mm if need be. But I have plenty of no more nails from doing the skirting. Want to put twin slot racking up a wall for books.

yes

your plug, and the screw, must both reach 25-35mm into the wall (disregard the plaster, which has no strength, and might be 12-20mm on top of the wall). Slotted supports need big long steel screws. The top one is the most important.

You can put a screw into the plug by a couple of turns and use it as a handle to push the plug into place.

Plugs should always be tapped slightly below the surface, so the plaster is less likely to crack, and it is easy to fill the surface flat when you remove the screw (don't try to pull out plugs)

Great, many thanks!