Working out how much PVA to use

[philipb82]

Hello

Now maths isn't my strong point and I'm planning on doing some plastering work in my spare bedroom. I want to get the ratios right first time, so I need some help figuring how to do it. I'm using Evo-stick Super evo bond PVA.

The instructions say for plastering: Primer coat - evo bond 1:5 and Adhesive coat - evo bond 3:1.

So for adhesive coat e.g. say I put 2000ml of pva in a paint kettle do I divide 2000ml by 3 giving me 666ml of water plus the 2000ml of pva? For primer coat e.g I put 1000ml of pva then 5 times as much water then add?

Sorry if this is basic stuff but I want to get it right first time. I'm alright with percentages but ratio's get me everytime!

Thanks

Phil

 

[joe-90]

Just use something like an old cup - 1 cup PVA to 3 or 5 cups of water. Nothing to work out.

 

[philipb82]

Right, that does sound a lot easier. I sometimes try and over complicate things a bit but I just want to do it right. Also do I need a primer coat if I'm skimming onto a painted wall?

Thanks

Phil

 

[PrenticeBoyofDerry]

Hello

Now maths isn't my strong point and I'm planning on doing some plastering work in my spare bedroom. I want to get the ratios right first time, so I need some help figuring how to do it. I'm using Evo-stick Super evo bond PVA.

The instructions say for plastering: Primer coat - evo bond 1:5 and Adhesive coat - evo bond 3:1.

So for adhesive coat e.g. say I put 2000ml of pva in a paint kettle do I divide 2000ml by 3 giving me 666ml of water plus the 2000ml of pva? For primer coat e.g I put 1000ml of pva then 5 times as much water then add?

Basically got it right.
But I would use the method of measurement with adhesive coat you used with the primer coat.
So 1000ml (1l) of water to 3000ml (3l) of PVA or divisions or multiples of that, so half of that would 500ml-1500mm, one and half times would be 1500ml-4500ml and so on.
But to get maximum usage with little waste, you would need to know the surface area to be covered.

 

[PrenticeBoyofDerry]

Right, that does sound a lot easier. I sometimes try and over complicate things a bit but I just want to do it right. Also do I need a primer coat if I'm skimming onto a painted wall?

Thanks

Phil

Yes.
I would also remove any loose/flaky paint, clean any dirt or grease from surface, and give the painted surface a little sand down, to create a key to help with adhesion.

 

[philipb82]

Basically got it right.
But I would use the method of measurement with adhesive coat you used with the primer coat.
So 1000ml (1l) of water to 3000ml (3l) of PVA or divisions or multiples of that, so half of that would 500ml-1500mm, one and half times would be 1500ml-4500ml and so on.
But to get maximum usage with little waste, you would need to know the surface area to be covered.

Ah right that makes sense, thanks. So for the primer coat, just for example sake 1000ml (1l) of PVA then 5000ml (5l) of water then mix together. Is it best to do this or the method joe-90 suggested?

Thanks

Phil

 

[PrenticeBoyofDerry]

Ah right that makes sense, thanks. So for the primer coat, just for example sake 1000ml (1l) of PVA then 5000ml (5l) of water then mix together.

Yes

Is it best to do this or the method joe-90 suggested?

.
If you have cup to measure with use that, if you have measuring jug use that.
Does not matter either way, it depends what measuring implements you have at your convenience and what you feel comfortable doing. The results in consistency of the mixture will be much the same

 

[philipb82]

Just a quick question, is it ok to use a trowel that is starting to go rusty? Mine is only a cheap one from a wholesalers (£3.30!!) but its got some little rust spots at one end. Is it worth buying a more expensive one?

Phil

 

[huddsspread]

sand the rust off....

 

[PrenticeBoyofDerry]

Just a quick question, is it ok to use a trowel that is starting to go rusty? Mine is only a cheap one from a wholesalers (£3.30!!) but its got some little rust spots at one end. Is it worth buying a more expensive one?

Phil

It's a cheap trowel and ferrous rather than stainless, so will rust over.
As suggested sand off or wire wool the rust off. If the trowel is starting to pit it may hinder the quality of finish.
Whether you buy new is up to you, the quality and price would depend on how much you intend to use the trowel.

 

[philipb82]

Thanks for the replies.

Also I have some Hardwall that expires on 6/6/12. Do I have to chuck out whatever is left on the expiry date or will it be ok for a few days after? Its stored in my house under the stairs on a concrete floor. Although I didn't realise that you have to put some wood or plastic underneath it if kept on a concrete floor, so I've recently done that! It's a warm house too.

Thanks

Phil

 

[philipb82]

Thanks for the replies.

Also I have some Hardwall that expires on 6/6/12. Do I have to chuck out whatever is left on the expiry date or will it be ok for a few days after? Its stored in my house under the stairs on a concrete floor. Although I didn't realise that you have to put some wood or plastic underneath it if kept on a concrete floor, so I've recently done that! It's a warm house too.

Thanks

Phil

My final question for a while!

Phil

 

[joe-90]

It should be fine. It just sets a bit quicker as it goes off.

 

[PrenticeBoyofDerry]

Also I have some Hardwall that expires on 6/6/12. Do I have to chuck out whatever is left on the expiry date or will it be ok for a few days after? Its stored in my house under the stairs on a concrete floor. Although I didn't realise that you have to put some wood or plastic underneath it if kept on a concrete floor, so I've recently done that! It's a warm house too.

I would take the expiry date with a pinch of salt, providing it has been kept in a dry area it should be okay to use.