My First Disaster

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herds said:
I will put that into practice next time. I'm just happy I didn't have a sucky wall the first couple attempts after the course, i'd have thrown in the trowel if that were the case.
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It's not often that you'd have to skim over bare plaster. Most of the time it will be PB or paint. To save yourself the headache, you could use Gyprime for high suction backgrounds or Bond-it for low suction backgrounds. Only one coat is required and each is applied the day before. However, sometimes the client doesn't want to pay out for the use of a bonding agent which means you'll need to use PVA. Also, if you have a small job to do ie one ceiling, if you can get away with using PVA it's much quicker because you just turn up at the job, lay down your protective sheets, start PVAing and get ready to skim.

Although, I've explained what to look out for when using PVA, if I was doing a small hit, I wouldn't completely seal the surface. Instead, I would apply the PVA and watch how it's being absorbed. Keep applying until it begins to become tacky and then immediately lay on my first coat of skim. If I was to kill all of the suction I'd be waiting around for ages for the first coat to pull in, so by not killing all of the suction the first cost of skim will pull in very quickly. I'd then apply pressure to remove any lines that were proud of 1mm. Mix up my second coat slighter wetter and lay it on. The second coat will liven up the first coat and I'd trowel up as normal. I wouldn't recommend this method until you can lay it on very quickly. Consider it food for thought.
 
Best way with very high suction walls is two coats of medium strength PVA followed by either blue grit or microgobetis. That'll give you plenty of time.

You can probably use other bonding agents but they are more expensive and I've no experience using them to kill suction.
 
Minh said:
It's not often that you'd have to skim over bare plaster. Most of the time it will be PB or paint. To save yourself the headache, you could use Gyprime for high suction backgrounds or Bond-it for low suction backgrounds. Only one coat is required and each is applied the day before. However, sometimes the client doesn't want to pay out for the use of a bonding agent which means you'll need to use PVA. Also, if you have a small job to do ie one ceiling, if you can get away with using PVA it's much quicker because you just turn up at the job, lay down your protective sheets, start PVAing and get ready to skim.

Although, I've explained what to look out for when using PVA, if I was doing a small hit, I wouldn't completely seal the surface. Instead, I would apply the PVA and watch how it's being absorbed. Keep applying until it begins to become tacky and then immediately lay on my first coat of skim. If I was to kill all of the suction I'd be waiting around for ages for the first coat to pull in, so by not killing all of the suction the first cost of skim will pull in very quickly. I'd then apply pressure to remove any lines that were proud of 1mm. Mix up my second coat slighter wetter and lay it on. The second coat will liven up the first coat and I'd trowel up as normal. I wouldn't recommend this method until you can lay it on very quickly. Consider it food for thought.
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Bonding agent doesn't cost any more than ova really.
 
DannyMac said:
Best way with very high suction walls is two coats of medium strength PVA followed by either blue grit or microgobetis. That'll give you plenty of time.

You can probably use other bonding agents but they are more expensive and I've no experience using them to kill suction.
Click to expand...
I'd just micro. It kills all the suction on its own
 
Yeah like you say same as gyprime. Prefer knauf's stuff. Cover about 150m2 diluted 50-50 for around £50. Sprayed it on with bigger jobs. Saves numerous coats of PVA :)
 
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