Board joints showing.....

[williamglossop]

I've been plastering a few years now. Its not my full time job, but I've done plenty of walls and ceilings. I'm pretty happy with the finish I get..... but one thing that plagues me a bit is the joints between boards showing up occasionally - usually where light hits an obtuse angle. I cant feel the joints and can't see them until its painted up - and usually only with a silk or vinyl finish.

Just wondering how you make sure they don't show up.... doesn't seem to matter how much a flatten in, they still show in the top coat.

 

[Deleted member 292770]

how many skim coats do you do?
what tape are you using?
tapered or square edge boards?
how big are the gaps in the board?

 

[williamglossop]

Always 2 coats
Use blue scrim tape
SE boards
1 mm gap between boards - butted up basically.

 

[Deleted member 292770]

So you’re saying you would not be able to feel that joint in the picture with your fingertips?

 

[williamglossop]

I can feel it once I know its there..... just wondering what technique would eliminate them.... or is it just a case of flattening more at the joins? Wondering if cross toweling too early might cause it.......

 

[Deleted member 292770]

what finishing trowel do you use?

 

[williamglossop]

I lay it on with a 14 inch stainless Marshall..... flatten with a 1200 st speedskim, repeat for 2nd coat. Then use the Marshall to flatten, then a wet trowel then finish with a 16 inch Nela Superflex. Sometimes ill polish it up with a refina plazi flex, but most times just leave it at the Nela stage.

 

[Deleted member 292770]

I rarely use plastic or thin bladed trowels on boards.
superflex run over the high spots rather than flattening and taking the ‘fat’ off.
I use a 20” marshalltown gold for my final trowel on boards and ceilings.
It’s a good sign really as it means your joint is full of plaster and basically bulging at the seam.
You just need a stiffer blade to drag it back off.

 

[Deleted member 292770]

You could also sponge or criss cross over the join with a wet 3” brush while you’re polishing up. That’ll do it.