skimming

by **neald** » Mon Aug 23, 2010 5:10 pm

hello everyone,i am busy skimming the living room walls in my house and on the 2 walls i've plastered small bubbles appeared in the middle and bottom of the walls and the plaster sagged and it took me quite a while to flatten it out,can anyone tell me what causes this?..thanks neal

by **Dan the man** » Tue Aug 24, 2010 9:37 pm

Could be a couple of reasons, did you skim over silk/eggshell paint?
Mixing the finish in a certain way causes air to be trapped in the mix and this causes dimples on the wall?
Sagging plaster is usually caused by low suction from the background of the wall, certain types of paint block the natural suction and can cause the plaster to hang around, flattening will be delayed and the overall finish can suffer as you have to use the natural catalyst in the plaster to be able to trowel up at the right moment.

by **neald** » Wed Aug 25, 2010 8:06 pm

[quote="Dan the man"]Could be a couple of reasons, did you skim over silk/eggshell paint?
Mixing the finish in a certain way causes air to be trapped in the mix and this causes dimples on the wall?
Sagging plaster is usually caused by low suction from the background of the wall, certain types of paint block the natural suction and can cause the plaster to hang around, flattening will be delayed and the overall finish can suffer as you have to use the natural catalyst in the plaster to be able to trowel up at the right moment.[/quote]hello mate,yeah it was silk paint i plastered over,the 2 remaining walls are also silk,would it be best to score the walls before skimming to give the plaster a better key?neal

by **Dan the man** » Thu Aug 26, 2010 12:50 pm

Well I wouldnt score it to much, best to use a bit of rough sand paper just to break the surface, and make sure when you pva the walls you let it dry before you skim it otherwise it will be sliding all over the place.
It is awkward when you skim over silk paint but you can still get a good finish, give it a good dry trowel a couple of hours after its done too.

Good Luck

by **neald** » Sat Aug 28, 2010 6:17 pm

[quote="Dan the man"]Well I wouldnt score it to much, best to use a bit of rough sand paper just to break the surface, and make sure when you pva the walls you let it dry before you skim it otherwise it will be sliding all over the place.
It is awkward when you skim over silk paint but you can still get a good finish, give it a good dry trowel a couple of hours after its done too.

Good Luck[/quote]i always let the pva dry and i lightly scored the walls and give it a sand,i did one wall today and it didn't sag at all so thanks for the advice and help mate...neal