Ive read the post( why not to use PVA as a tiling primer) and decided i would use an acrylic primer after asking advice on here. After a long slog of a job which ive now near finished (thank god) I decided instead of doing the tiling myself i would get a tiler in, he said he would use pva as a primer. He doesnt seem to be alone in this other people ive asked who do tiling said they use pva. I rang bal tech and they said they wouldnt recommend it use. So to try and make some sense out of it i rang unibond tech and asked do they recommend pva as a tiling primer and the guy says yes use "super pva" diluted 5 to 1. I then mentioned what i had seen on the net over not using pva as it formed a skin on the surface of the plaster, he said diluted that thin it wouldnt do that but would pass through. So can anyone clear this up its got me confused.
Confused over PVA
- Thread starter Hotwire
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This argument just goes round in circles - no one can give a truely convincing argument not to use PVA. There are many tilers on here that have been using PVA for many years and "haven't had any problems". However maybe their customers have experienced problems but are reluctant to get the same tiler back in to sort it. 
at last someone answered Quote Hotwire " I rang bal tech and they said they wouldnt recommend it use. So to try and make some sense out of it i rang unibond tech and asked do they recommend pva as a tiling primer and the guy says yes use "super pva" diluted 5 to 1. I then mentioned what i had seen on the net over not using pva as it formed a skin on the surface of the plaster, he said diluted that thin it wouldnt do that but would pass through." i agree 100% on this and like ive said in the past BAL will not recommend any other PRODUCT other than theirs, who would. PVA has been used for a hundred other things other than glueing MDF fire places together.
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Pardon me for asking what might seem to be a dumb question, but what is a "tiling primer" and...
0. when someone says "use PVA as the tiling primer" do they mean that one should paint diluted white wood glue onto a wall?
1. do you use it over any and every subtrate you want to tile over, or only plasterboard and plaster?
2. what is the purpose in using a tiling primer before tiling?
3. why is it that you do not want the tiling primer to form a film?
4. if the problem with the tiling primer forming a film is that this film would not be water proof, why not use a concrete bonding agent instead as the tiling primer?
5. Do you tile directly onto the tiling primer?
This is the first I've heard of using a "tiling primer". We use waterproofing membranes here which can be painted onto walls to provide a waterproof layer between the plaster or plasterboard and the ceramic tiling.
0. when someone says "use PVA as the tiling primer" do they mean that one should paint diluted white wood glue onto a wall?
1. do you use it over any and every subtrate you want to tile over, or only plasterboard and plaster?
2. what is the purpose in using a tiling primer before tiling?
3. why is it that you do not want the tiling primer to form a film?
4. if the problem with the tiling primer forming a film is that this film would not be water proof, why not use a concrete bonding agent instead as the tiling primer?
5. Do you tile directly onto the tiling primer?
This is the first I've heard of using a "tiling primer". We use waterproofing membranes here which can be painted onto walls to provide a waterproof layer between the plaster or plasterboard and the ceramic tiling.
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gcol, stop it your confusing me more
jbonding, i cant really comment as my tiling experience doesnt come to much, but a lot of people seem to use pva. The last time i tiled i simply used tub adhesive and spread it over the emulsion paint in my bathroom that was 20yrs ago and those tiles were still firmly in place till i took them down last year. I posted pictures of the wall with plaster missing on here. The only reason i am concerned over these tiles that need to go up is there weight as you will know having answered some of my previous posts
Nestor_Kelebay, i will try to answer some of your questions although i am only an amateur in these matters. Its mostly knowledge i have gained here.
Yes pva wood glue is diluted and applied to surfaces that absorb water rapidly such as plaster. This is to stop/slow down its rate of suction so the adhesive drys more naturally and i presume gives a stronger bond. You dont want the primer to form a skin as the tiles will bond to this thin skin and not the wall itself, not an ideal situation.
jbonding, i cant really comment as my tiling experience doesnt come to much, but a lot of people seem to use pva. The last time i tiled i simply used tub adhesive and spread it over the emulsion paint in my bathroom that was 20yrs ago and those tiles were still firmly in place till i took them down last year. I posted pictures of the wall with plaster missing on here. The only reason i am concerned over these tiles that need to go up is there weight as you will know having answered some of my previous posts
Nestor_Kelebay, i will try to answer some of your questions although i am only an amateur in these matters. Its mostly knowledge i have gained here.
Yes pva wood glue is diluted and applied to surfaces that absorb water rapidly such as plaster. This is to stop/slow down its rate of suction so the adhesive drys more naturally and i presume gives a stronger bond. You dont want the primer to form a skin as the tiles will bond to this thin skin and not the wall itself, not an ideal situation.
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Hotwire:
If the PVA glue is intended to partially seal the porous surface of the wall your tiling to prevent the "glue" from drying out too fast, then:
a) why wouldn't it make even more sense to use a concrete bonding agent as the "tiling primer" since the resins of the bonding agent will plug up the porosity of the wall just as effectively as a white PVA wood glue will.
b) concrete bonding agents work by crosslinking after they've been applied. That is, some time from a few days to a few weeks after the concrete bonding agent is applied, a chemical reaction occurs which crosslinks all the resins together so that the resulting "macromolecule" is now too big to go back into suspension in the water, and the resulting film is then waterproof. If it's not a good idea to have a non-waterproof film of wood glue over the wall, why is it not a good idea to have a waterproof film of concrete bonding agent over the wall which will both provide good surface of the tile mastic to adhere to and also protect the wall from moisture?
c) instead of a tiling primer, is there any reason not to use a waterproofing membrane (like the Redguard product popular here in North America) instead. Basically, it's meant for exactly what you describe. You paint it directly onto the surface you want to tile, and it forms an impermeable waterproof film that tile mastics and thin sets will adhere well to. These waterproofing membranes come both as a liquid you paint on and as a film you press on:
http://www.laticrete.com/Pages/waterprftrsht.htm
here's one that comes as a film you put down before tiling floors:
http://www.protectowrap.com/cat_floor_waterp.php
and if you Google "waterproofing membrane" you'll find all kinds of them, mostly made of bitumen for re-roofing. Search within results for "Tile" to find those meant for floor and wall tiling.
Please advise me if these last two posts of mine are considered "hijacking" a thread and I will refrain. (?)
If the PVA glue is intended to partially seal the porous surface of the wall your tiling to prevent the "glue" from drying out too fast, then:
a) why wouldn't it make even more sense to use a concrete bonding agent as the "tiling primer" since the resins of the bonding agent will plug up the porosity of the wall just as effectively as a white PVA wood glue will.
b) concrete bonding agents work by crosslinking after they've been applied. That is, some time from a few days to a few weeks after the concrete bonding agent is applied, a chemical reaction occurs which crosslinks all the resins together so that the resulting "macromolecule" is now too big to go back into suspension in the water, and the resulting film is then waterproof. If it's not a good idea to have a non-waterproof film of wood glue over the wall, why is it not a good idea to have a waterproof film of concrete bonding agent over the wall which will both provide good surface of the tile mastic to adhere to and also protect the wall from moisture?
c) instead of a tiling primer, is there any reason not to use a waterproofing membrane (like the Redguard product popular here in North America) instead. Basically, it's meant for exactly what you describe. You paint it directly onto the surface you want to tile, and it forms an impermeable waterproof film that tile mastics and thin sets will adhere well to. These waterproofing membranes come both as a liquid you paint on and as a film you press on:
http://www.laticrete.com/Pages/waterprftrsht.htm
here's one that comes as a film you put down before tiling floors:
http://www.protectowrap.com/cat_floor_waterp.php
and if you Google "waterproofing membrane" you'll find all kinds of them, mostly made of bitumen for re-roofing. Search within results for "Tile" to find those meant for floor and wall tiling.
Please advise me if these last two posts of mine are considered "hijacking" a thread and I will refrain. (?)
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Hotwire:
Perhaps the purpose in using a PVA primer over the wall surface lay in the fact that these may be exterior walls that are being tiled.
If they are, then it would be normal for them to be insulated, probably with a fiberglass batt insulation (which is what we use here) and a plastic vapour barrier stapled to the studs over top of that fiberglass insulation.
If there is plaster or plasterboard installed over top of that plastic vapour barrier, then any waterproof membrane you apply over the plaster or plasterboard would end up sandwiching it between two impermeable layers, and that's never a good idea. If water were to get in between those two impermeable layers (the vapour barrier and the waterproofing membrane) from a roof leak, leaking water pipe or toppled aquarium stand and soak into the plaster or plasterboard, it would take forever and a day to dry out.
So, perhaps the reluctance to use a waterproofing membrane over the wall prior to tiling has to do with the concern about sandwiching the wall plaster or plasterboard between two impermeable layers. (?) If they used a PVA primer on the wall (or just about any water based product that forms a film), then that film would typically allow water molecules to pass through it, but not allow liquid water to pass through it, and therefore would allow any wet plaster board or plaster to dry out.
(still, the glazed ceramic tiling itself a very highly impermeable layer too, so I'm sure there's any way to avoid having the plaster or plasterboard sandwiched between two impermeable layers if this is an exterior wall no matter what you do, short of taking the wall plaster or plasterboard down and replacing the fiberglass batt insulation with extruded polystyrene insulation which is itself impermeable to air or water and therefore doesn't need a vapour barrier over it)
Perhaps the purpose in using a PVA primer over the wall surface lay in the fact that these may be exterior walls that are being tiled.
If they are, then it would be normal for them to be insulated, probably with a fiberglass batt insulation (which is what we use here) and a plastic vapour barrier stapled to the studs over top of that fiberglass insulation.
If there is plaster or plasterboard installed over top of that plastic vapour barrier, then any waterproof membrane you apply over the plaster or plasterboard would end up sandwiching it between two impermeable layers, and that's never a good idea. If water were to get in between those two impermeable layers (the vapour barrier and the waterproofing membrane) from a roof leak, leaking water pipe or toppled aquarium stand and soak into the plaster or plasterboard, it would take forever and a day to dry out.
So, perhaps the reluctance to use a waterproofing membrane over the wall prior to tiling has to do with the concern about sandwiching the wall plaster or plasterboard between two impermeable layers. (?) If they used a PVA primer on the wall (or just about any water based product that forms a film), then that film would typically allow water molecules to pass through it, but not allow liquid water to pass through it, and therefore would allow any wet plaster board or plaster to dry out.
(still, the glazed ceramic tiling itself a very highly impermeable layer too, so I'm sure there's any way to avoid having the plaster or plasterboard sandwiched between two impermeable layers if this is an exterior wall no matter what you do, short of taking the wall plaster or plasterboard down and replacing the fiberglass batt insulation with extruded polystyrene insulation which is itself impermeable to air or water and therefore doesn't need a vapour barrier over it)
Nestor_Kelebay, most of what your saying is over my head. Im not a builder so i cant comment on things such as (concrete bonding agents) having never used them or come to think of it, heard of them. I cant answer your questions as i just dont have the knowledge but maybe someone else will.
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Hotwire:
Hopefully someone will explain why to use PVA as a "tiling primer" when there are products on the market (like the Laticrete) that are meant to be applied over walls to waterproof them prior to tiling.
I think part of the confusion over whether or not it's appropriate to use PVA is that people might not be aware that there are many different PVA resins. Most PVA resins used to make inexpensive paints and wood glues soften up considerably if they get wet. However, just in the same way that you can get acrylic resins that crosslink, you can also get PVA resins that crosslink. Crosslinking means that after the resins form a film, they form chemical bonds with all their neighbors so that the resulting film becomes one huge "macromolecule". If a PVA product does that, then once it's crosslinked to form a single huge molecule then it won't be affected by water the same way since now there are chemical bonds holding all the resins in place so that they can't fall redissolve into the water if they get wet. So, you can have PVA wood glues that come apart if they get wet and you can also have PVA tiling primers that don't come apart if they get wet (as long as that crosslinking has already taken place).
Exactly the same thing happens with linseed oil. As long as it's an oil freshly squeezed out of a flax seed, then it'll dissolve in turpentine or white spirits. But once you paint it on a wall and it has a chance to crosslink with all the other linseed oil molecules around it, then what you have is a single huge macromolecule covering the wall, and you can wash that wall with turpentine or white spirits all day long and no oil molecules will come loose from it.
Hopefully someone will explain why to use PVA as a "tiling primer" when there are products on the market (like the Laticrete) that are meant to be applied over walls to waterproof them prior to tiling.
I think part of the confusion over whether or not it's appropriate to use PVA is that people might not be aware that there are many different PVA resins. Most PVA resins used to make inexpensive paints and wood glues soften up considerably if they get wet. However, just in the same way that you can get acrylic resins that crosslink, you can also get PVA resins that crosslink. Crosslinking means that after the resins form a film, they form chemical bonds with all their neighbors so that the resulting film becomes one huge "macromolecule". If a PVA product does that, then once it's crosslinked to form a single huge molecule then it won't be affected by water the same way since now there are chemical bonds holding all the resins in place so that they can't fall redissolve into the water if they get wet. So, you can have PVA wood glues that come apart if they get wet and you can also have PVA tiling primers that don't come apart if they get wet (as long as that crosslinking has already taken place).
Exactly the same thing happens with linseed oil. As long as it's an oil freshly squeezed out of a flax seed, then it'll dissolve in turpentine or white spirits. But once you paint it on a wall and it has a chance to crosslink with all the other linseed oil molecules around it, then what you have is a single huge macromolecule covering the wall, and you can wash that wall with turpentine or white spirits all day long and no oil molecules will come loose from it.
Doing my own tiling so thought I'd do it proper. Bought BAL tile primer. Horrid stuff. Went to put it on with a skinny 4" roller and it just stuck and picked up. Dry in seconds. Added a tiny bit of water and it was better.
The end result is nothing like PVA, the surface is dry but "tacky" like a posh table tennis bat even after 3 days. The parts where I used it without the water are identical, by the way!
The end result is nothing like PVA, the surface is dry but "tacky" like a posh table tennis bat even after 3 days. The parts where I used it without the water are identical, by the way!
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