glass mosaic backsplash onto painted drywall... prime?

[swixusa]

I bow to the fellow Experts. You are the greatest and I need your help.

I was about to start putting up a glass mosaic backsplash in the kitchen, did layout - woohoo, it took me an awful while with nipping/snapping/filing and cutting schluter edging profiles. But being concerned about the wall prepping (too much of contradictory advice of all sorts all over the web) I did a duct tape test that I found on youtube [ v=NEioEiASU7w ]. I put a piece of duct tape on the wall, pulled it and some coating peeled off. So, following the recommendations I started scrapping it off in panic - I want my backsplash to last!!! Now...

SITUATION:

1) It is an old drywall, used to have seamy-gloss on, I TSP cleaned it and primed / sealed (Kiltz and/or Roman Rx-35 - the wall was disgusting behind old cabinets, so i sealed it all)
2) One wall has a few inches pained at the top - I originally planned to have the tile go lower. The paint is dark gray. Glass tile is translucent with white backing.
3) Not all the walls have the paint/sealer pealing off with duct tape as easily. I started scraping off the worst one. Others had a tiny bits of paint come off
4) In one corner the tile will go as high as 26" - corner with dark gray paint, about 28"x11" in length. Paint doesn't peel off as easily there.
5) wall that peels off easier has a large window above the sink with about 14" on each side.

MATERIALS:

a) glass/ceramic mosaic tile by Jeffrey Court
b) 1" x 2" subway tile for edge by the door (5 tiles wide)
c) Glass Tile Premium Thin-Set Mortar by CustpomBuilding
d) have some KILTZ primer
e) LASTLY, I have AcrylPro ceramic tile Adhesive by Custom, which I understand it is not recommended for glass no matter how small individual tiles are. BUT, contractors that installed the same tile on the opposite accent wall used it while I wasn't watching even though I had the right thin set for them.


QUESTIONS:

1) Shall I keep scraping off the paint/sealer? All over or only where it comes off easier?
2) Shall I prime before I start tiling? The wall under te paint is a bit chalky (may be that's why paint/sealer peeling off). There was some patching done after electrical work.
3) shall I white-prime over the painted wall, so the color wouldn't "bleed" through? I have no idea what the backing of the translucent white tile is - I soaked it in water, tried to scratch and wasn't able to.
4) shall I use different thinset for ceramic subway and glass mosaic?
4) LASTLY: shall I just use the same mastic that was used by contractors on the accent wall? My concern is the color. I was told that mastic might result in tile turn yellow, and with paranoid eye, almost can see it in places at certain angle (accent wall was installed 4 months ago)

[swixusa]

White subway on both sides of the doorway. All the rest glass mosaic. It will be symmetrical

[Houston Remodeler]

Svetlana,


0- thanks for numbering your questions

1- The loose, gooey, oily, or dusty spots have to be repaired. If its dry, clean, secure and smooth you are ok

2- You can, we normally do for glass tiles. But be sure to have it as clean and free from debris as possible. See #1

3- It can't hurt. See #2

4- You can use the rest of the glass thinset up first if you desire, then switch to white versabond for the ceramic tiles

5- DO NOT use mastic for the glass tiles. Also do not use mastic of you need to use the mastic to adjust the height of the tiles. Mastic shrinks as it dries so it doesn't fix tile thickness like the powdered stuff. White versabond sells for $14 a bag in these parts. Pretty darn cheap insurance if you ask me.

[swixusa]

Thank you very much Paul.

So, I settled on decision to use Premium Glass Mosaic Mortar by Custom. But what I wonder about is: will ceramic 1x2" subway tile stick to the same mortar or I absolutely have to open a new bucket of premixed adhesive - same mastic that was used for ALL the tile on accent wall by contractors? I'll have merely 5-6 sq ft of ceramic tile surface.

Another question:
I also have schluter edging profiles. Do I nail them to the wall or try to set on thinset. Schluter tutorial I watched didn't show the nails or screws, but I am afraid it will be hard to manage without securing the frame to the wall first...

[jondon]

Hi Svetlana

So mastic was previously used by the contractor for the subway tile around the tub. I would treat the area you are doing separate yes mortar or thinset is
going to stick and always better than mastic for the reasons Paul stated.

As for the Schluter profiles I find it better to not nail it into place. If you do this then you cannot adjust it if you need to when you are setting the tile. A lot of times there is nothing behind the drywall to hold it securely. I put them into place as I am putting the tile in.

[swixusa]

Thank you Jon for your advice on installing profiles...

And... from what you are saying... ceramic mini-brick tile will not stick on thinset? (Premium Glass Mosaic Tile Mortar by Custom). That's wasteful - opening a new bucket of mastic when I only have total length of 5-6 ft long strip of ceramic tile about 1 ft wide...

[evan1968]

Please toss that bucket of mastic out and never speak of it again. Lol
The ceramic will stick to your glass thinset just fine.

[swixusa]