Plaster skim must be sanded before applying APD Primer - TilersForums.co.uk | Tile Forums

pendleh · 08-02-2008

Hi there

Wondered what you would use to rough up the glassy surface of a new plaster skim prior to tiling? Just some sand paper and a block? Any ideas appreciated.

Best Wishes

Howard

tilinga2z · 08-02-2008

Why do you rough up plaster skim it is fine to tile on as is, some painted surfaces maybe but clean dry plaster skim IMO no.

pendleh · 08-02-2008

Thanks for that. Just reading my PTS manual and it says:

[FONT='Times New Roman','serif']Smooth glassy surfaces must be sanded?[/font]
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[FONT='Times New Roman','serif']What does IMO mean. thanks for the reply.[/font]
[FONT='Times New Roman','serif'][/font]
[FONT='Times New Roman','serif']Best Wishes[/font]
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[FONT='Times New Roman','serif']Howard[/font]

tilinga2z · 08-02-2008

IMO in my opinion

GazTech · 08-02-2008

[quote=tilinga2z;53782]Why do you rough up plaster skim it is fine to tile on as is, some painted surfaces maybe but clean dry plaster skim IMO no.[/quote]My mate Alan...great plasterer, work in a team yrs ago , and they all hated one painter....so if they knew he was painting a certain plot, they would set brew room up in bedroom upstairs. Every time they went for a brew or dinner ......walking up stairs they would spit on trowel and polish up the wall leading upstairs. By the time the painter came to paint the wall it was like glass..lol....the paint just ran off onto the floor and he had to sand it down for a key...pmsl :lol::lol::lol:

pendleh · 08-02-2008

Hi Gaz Would you rough up shiny plaster skim prior to tiling?

**grumpygrouter** · 08-02-2008

I would rough up a polished finish plaster skim before tiling too. Although the primer itself would help to give a better key, it is better to be safe than sorry. I would use my orbital sander with a course paper.

grumpy

pendleh · 08-02-2008

Hi Grumpy

Thanks for that. I have a belt sander is this a bit too heavy duty?

**grumpygrouter** · 08-02-2008

Quote:

Originally Posted by pendleh

Hi Grumpy

Thanks for that. I have a belt sander is this a bit too heavy duty?

No, you will just get the job done quicker. Quick whizz over the surface to rub it up, wipe off your excess dust and then apply the APD. Let it dry and you are ready to tile.

What you need to be aware of though is that you don't confuse a new "smooth" plaster skim with a "polished" skim. My understanding of a "polished" finish is that it was desigend to be the end decorative product and didn't need anything else.

Some of the qualified plasterers on here will probably give better info on that as I am not a plasterer. But if you are in doubt, sand and prime. The only thing it is costing you is little extra time for your sanding. better to be safe than sorry.

Grumpy

**Dave** · 08-02-2008

SHINY PLASTER SHOULD BE LIGHTLY ROUGHED UP FOR TILING....i use a wire brush if its really shiny much quicker than sanding...its just a case of opening up the surface pores for the adhesive to crystallize into....

This is the advise by BAL....same as most adhsives manufactures advise...

NEW GYPSUM PLASTER: Before commencing tiling. Ensure that
the plaster has allowed to dry out by exposure to air for at least 4
weeks. Ensure that the finish coat has been applied and that the
plaster is free from dust, efflorescence and friable material. Cut
back any defective areas, including badly cracked plaster, to
straight horizontal and vertical edges. Thoroughly dry brush
background and edges and make good with plaster or a suitable
non-0shrinking filler. Plaster having a shiny, polished surface
should be thoroughly brushed with a stiff bristled brush, followed
by priming with a 1:4 BAL-BOND SBR: water mix or a 1:1 BALPRIME

APD: water mix. Allow the primer to dry.

pendleh · 09-02-2008

Thanks for all your great help. Im new as you can guess and you lot are a fantastic help. So is the site!