Sanding old grout from a plasterboard/honeycomb wall

[Nikkob]

Can anyone offer any advice on how i can sand back old grout on a plasterboard wall, the wall will then be retiled so will i need to prepare the wall in any way?

 

[Nestor_Kelebay]

I guess things are done differently in England than they are where I live.

If the tiles were put up with mastic and then grouted, then there will be a thin layer of mastic over the plasterboard and then any grout will be sticking to that mastic.

What I've found works very well at removing old mastic is if you take a single edge razor blade and grip it in the jaws of a pair of needle nose style Vice Grip pliers, you have a very sharp all-metal tool that will take a lot of heat and that when held upside down will hold the razor blade at a near perfect angle for scraping.

Now, if you use an electric heat gun to heat that old mastic, you will soften it considerably, and you can then use that tool described above to scrape the old mastic off the wall quite quickly and easily.

In your case, will removing the old mastic also remove the grout?

Several PS's:

1. Whenever working in a tub or shower, put a piece of scrap carpet pile side down in the tub to protect it from scratches.

2. Use a short piece of twine to tie the Vice Grip tool to a leather glove you'll be wearing when holding it. That tool will get pretty hot, and you'll need a leather glove to protect your hand from the heat. Also, the twine will prevent the tool from falling and possibly chipping the surface of the tub if you drop it.

3. You can do this kind of work with a cheap electric heat gun. However if you don't have any experience using heat guns, you'll be very surprised at how useful they are in DIY work, and I'd recommend you pay more for one with electronic temperature control. Electronic temperature control will allow you to adjust the temperature so that you can strip varnish or paint off wood quickly and easily without scorching the wood. Cheap heat guns have only two settings; Hi and Lo, and that's too restrictive to be very useful in a lot of cases.

 

[Nikkob]

thanks for the reply, it doesn't look like there is any mastic on the wall, just old tile adhesive, some coarse filler and plasterboard. Will a belt sander with a coarse paper on it do the job? the wall looks a little fragile to use a heat gun on

 

[Nestor_Kelebay]

I've never used a belt sander on a wall, so I can't advise you if or how that would work.

What about buying one of those paint scrapers made by Sandvik with the replaceable super-hard tungsten carbide blades? I'm thinking you may be able to scrape a soft cement based material down with one of those.

 

[Nikkob]

I shall look into the Sandvik scraper, do you think a heat gun would still be of any use in this situation or is that only for mastic?

ps.

is this scraper sold in diy shops or is it more a builders merchants tool?

 

[Nestor_Kelebay]

Most hardware stores will sell paint scrapers, but not all of them will sell the Sandvik. I like that scraper a lot because the blade is very hard and stays sharp a long time. Also, it's sharp enough to scrape, but not so sharp as to gouge wood unintentionally.

A heat gun won't help if it's a cement based product you're trying to soften. A heat gun will soften mastic up a lot. It won't soften grout at all.

 

[confidentincompetent]

Can anyone offer any advice on how i can sand back old grout on a plasterboard wall, the wall will then be retiled so will i need to prepare the wall in any way?

Have you by any chance tried soaking the old adhesive? You might be lucky that it's a ready mixed non waterproof type. I usually try soaking with hot water (use old brush) with a little washing up liquid in, leave to soak a while then soak again you may find it just scrapes off with a paint scraper. Try a little area first (carefull you dont dig into plasterboard). If not, I use an old broad paint scraper, old wood chisel and hammer to chip away. Depending what you got some more knowledgeble might say rip the p/board off and replace
good luck.

 

[Nikkob]

thanks for all your help, I think through all the replies I have come up with a plan of action - scraper and hot water (I have a wall paper stripper which seems to be popular on other forums / websites, which I will try), and to be honest if it comes to it new plasterboard.

 

[Nikkob]

just an update, scraper and wall paper stripper worked a treat, think i`ll need to seal the wall someway, any ideas? cheers