Trowelling

by Wayne
(Jersey)

Hi Paul

Loved the DVD good value for money, Hope you can help. I am confident that I am laying on to correct thickness and achieving pretty flat finish, but were I seem to have a problem is when I get to the final stages of troweling, it's the stage were the plaster is changing from creamy colour to darker blotchy streaky colour . The wall looks like it has a skin and if left it comes off with my watered down paint mix. If I try to clean it at the troweling stages I seem to be taking the nice finish back off leaving half smooth half rough which then shows in painted finish. Am I simply doing final troweling to soon or to late or not trowelling enough I am confident that I am putting enough pressure on final stages but not sure. I have a top class marshal town trowel don't think problem lies there. Any help would be great

Cheers Wayne

Hi Wayne,
I am thinking it may not be a troweling issue but possibly more with the application. If its peeling off it is more likely to be either a bonding or suction issue.
The plaster can flake off when troweled if it becomes too dry underneath - or the exact opposite and the finish is being applied to a low suction wall and the PVA has not dried enough before applying plaster.
One of the following 3 points may help:

If the wall was high suction and the plaster firms up in less than 30mins then try controlling the suction either with damping the wall down more than you did or by applying a solution of PVA to seal the surface.

If the wall was high suction and you applied PVA for bonding purposes then make sure it goes tacky before applying plaster.

There is a possibility that the second coat is not adhering to the first coat. This can only really happen if the first coat begins to set before the second is applied. The second coat should generally be applied within an hour of the first or sooner - as soon as it goes tacky.

If you're still having problems you can always email me anytime.

Paul

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Apr 08, 2015
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by: Paul

Hi Wayne,

You say when you trowel too soon you take off the fat and leave holes everywhere. This may explain where you could improve really easily.
All the problem seems to be is the angle of your trowel - it just needs to be a bit flatter, so that when the back edge is in contact with the wall the front leading edge should be between 10 and 15mm away from the wall. Then no matter how soon you trowel it the plaster will just get pushed around.

If the leading edge is too far away the trowel will act in a way that scrapes any highs off and the residue will collect on your trowel. Whereas if you have the trowel flatter to the wall the highs will not be scraped off, but if firm pressure is applied, will be pushed into the low areas and fill the holes.
Feb 09, 2015
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by: Wayne

Hi Paul thanks for the advice, the problem I am having is when I trowel the wall and spread the fat/glut around to fill the holes etc, i seem to be struggling with timing I think, not sure if trowelling to soon or to late how do I tell when it is time to do second trowel and final trowel, if I trowel it to soon I seem to take the fat off leaving holes every where if I leave it to late I seem tear at the surface taking the fat off leaving holes, applying plaster when pva almost dry but still tacky on the finger tips, second coat when plaster is cheesy, using spray bottle on finest mist just enough to lubricate trowel.

Cheers wayne

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