Badly damaged walls - advice needed!!

[peaps]

That would mean the pva is dry, no?

Yes it would. First coat 5/1 water/pva put on, allowed to dry. Second coat 3ish/1 pva/water put on, skimmed while tacky. As advised by an untold number of plasterers on this very board.

But why would you first coat pva the day before, not the most time consuming job to do.

Who mentioned skimming dry pva? I'm just assuming "badly damaged walls" may need some sorting out the evening before skimming at least.

Not what you said....

 

[stevethespreader]

But why would you first coat pva the day before, not the most time consuming job to do.

really peaps after reading your posts i have to ask you what your trade is

 

[peaps]

But why would you first coat pva the day before, not the most time consuming job to do.

really peaps after reading your posts i have to ask you what your trade is

I'm a plasterer, 23 years and 98% of my work I utilise traditional methods working on listed buildings. I spent 5 years training as an apprentice and an extra year fibrous casting. I do some knock out venetian plastering as well.

 

[Richard C]

Yes it would. First coat 5/1 water/pva put on, allowed to dry. Second coat 3ish/1 pva/water put on, skimmed while tacky. As advised by an untold number of plasterers on this very board.

Where have “untold numbers of plasters on the very board” advocated that PVA ing is necessary the night before a conventional re-skim; I’ve been here since 2004 & none of the spreads I know who still contribute on a daily basis & others that have since disappeared have ever advocated that; lets have some post links!

I reiterate what I said in my earlier post; PVA the day before is only necessary where it’s being used as a bonding coat on difficult & non porous surfaces; Artex, gloss/acrylic paint, tiles etc usually applied over a very much scored surface & often mixed with plaster or cement & left to dry out. All that’s needed the following day is a light wash coat of PVA, just enough to liven the surface; if you over scrub it, the whole lot re-emulsifies & defeats the object. For conventional skim over emulsion or base coat, PVA is primarily used to control suction & in this case you will do 2 coats in fairly quick succession in the first 20 minutes or so & skim when tacky but with new base plaster or render, plain old water is generally much better anyway.

You’re posting misleading information about the use of PVA & I don’t understand why some of the other experienced spreads haven’t commented on this so far.

 

[joe-90]

You’re posting misleading information about the use of PVA & I don’t understand why some of the other experienced spreads haven’t commented on this so far.

Cuz God's on the case.

 

[peaps]

Yes it would. First coat 5/1 water/pva put on, allowed to dry. Second coat 3ish/1 pva/water put on, skimmed while tacky. As advised by an untold number of plasterers on this very board.

Where have “untold numbers of plasters on the very board” advocated that PVA ing is necessary the night before a conventional re-skim; I’ve been here since 2004 & none of the spreads I know who still contribute on a daily basis & others that have since disappeared have ever advocated that; lets have some post links!

I reiterate what I said in my earlier post; PVA the day before is only necessary where it’s being used as a bonding coat on difficult & non porous surfaces; Artex, gloss/acrylic paint, tiles etc usually applied over a very much scored surface & often mixed with plaster or cement & left to dry out. All that’s needed the following day is a light wash coat of PVA, just enough to liven the surface; if you over scrub it, the whole lot re-emulsifies & defeats the object. For conventional skim over emulsion or base coat, PVA is primarily used to control suction & in this case you will do 2 coats in fairly quick succession in the first 20 minutes or so & skim when tacky but with new base plaster or render, plain old water is generally much better anyway.

You’re posting misleading information about the use of PVA & I don’t understand why some of the other experienced spreads haven’t commented on this so far.

pva is used incorrectly when it comes to control of suction. It's a bonding agent, a glue and is bad practice to use to control suction, defeats the object of plastering.

 

[joe-90]

I'm beginning to think Peaps is just a silly troll.

 

[Richard C]

I'm beginning to think Peaps is just a silly troll.

Now he's having a pop at me, I think you may be right; what utter drivel

 

[joe-90]

Who would have a pop at God?

 

[Richard C]

8)

 

[peaps]

I'm beginning to think Peaps is just a silly troll.

I'm beginning to think Peaps is just a silly troll.

Now he's having a pop at me, I think you may be right; what utter drivel

You always find that people revert to slagging off others when they are unable to back up their theory....

If you think pva is designed for suction control then support your assertion.

"Polyvinyl alcohol has excellent film forming, emulsifying, and adhesive properties. It is also resistant to oil, grease and solvent. It is odorless and nontoxic. It has high tensile strength and flexibility, as well as high oxygen and aroma barrier properties. However these properties are dependent on humidity, in other words, with higher humidity more water is absorbed. The water, which acts as a plasticiser, will then reduce its tensile strength, but increase its elongation and tear strength. PVA is fully degradable and dissolves quickly. PVA has a melting point of 230°C and 180–190°C(356-374 degrees Fahrenheit) for the fully hydrolysed and partially hydrolysed grades, respectively. It decomposes rapidly above 200°C as it can undergo pyrolysis at high temperatures.

PVA is an atactic material but exhibits crystallinity as the hydroxyl groups are small enough to fit into the lattice without disrupting it.

PVA is close to incompressible. The Poisson's ratio has been measured to between 0.42 and 0.48.[1]"

http://en.wikipedia.org/wiki/Polyvinyl_alcohol

Pva seals a porous wall and creat a barrier between the wall and plaster, it glues the plaster to the wall. Why anyone would pva a "newly" plastered wall is beyond me but I do understand that it's common practice amongst self trained plasterers.

Keep up and ou might even learn something.

 

[joe-90]

It's called experience. Something you obviously lack.

 

[peaps]

It's called experience. Something you obviously lack.

I only see the lack of, I have 23 years behind me, what about you? I do believe we have bumped into one and other before, you had just started out and that wasn't too long ago.

Converse this experience and put me stright if you feel confident.....

 

[Richard C]

Water is by far the best for controlling suction on new render, blocks or base coat plaster (that has been allowed to dry out) but, in your opinion, the thousands of experienced spreads that use PVA to provide a bond & control suction when re-skimming have obviously got it wrong then; it does both depending on the strength you use & how you apply it.

Think your suffering from a severe dose of wiki mania peaps

 

[Micilin]

Be careful with the internet ..........

Polyvinyl alcohol (PVOH, PVA, or PVAl) is a water-soluble synthetic polymer (not to be confused with polyvinyl acetate, a popular wood glue). ...

Poly Vinyl Acetate anyone?