sm_jamieson wrote:
On 31 Jan, 20:00, "Phil L" wrote:
2) get a coat of plaster on the entire wall, don't bother about any
marks,
lines or anything else, just make sure the entire surface is covered
fairly evenly (even as in the same thickness - don't have it a mm in
one part and
half an inch thick elsewhere, unless this is unavoidable.)

Of course, this, in my experience is the hard part. Polishing and
stuff is easy, but if you can't judge flatness
at this stage (or on any second coat - but I've never seen a pro doing
plasterboard skim in 2 coats), the later stages will not correct it.
You can only shove the plaster around later to correct a certain
amount of wobbliness. You can remove localised dips, scrapes etc
later, but if the initial flatness is not close enough, you have a
problem. And this is where I got stuck.

The first coat is primarily to fill any deep undulations...this is allowed
to partially set before the 2nd coat is applied - yes, some parts of it may
be 12mm thick while others are only 2-3mm, but the wall would have to be
seriously rough for this to be the case, thick artex for example.
PB doesn't always need 2 coats - most pros give it 2 coats because it's
easier to get a final finish, but if it's the only patch they're doing, they
may just do it in one - if they are doing a full house or a few rooms,
everything gets 2 coats because you have more time, IE you can first coat 2
walls, then with the next mix, second coat those and put 1st coat on a
third, then trowel up the first two and your next mix will second coat the
third and maybe get another wall first coated etc - in this scenario, doing
it in one isn't really an option because it goes off too quick and your
meterage is severely curtailed, inthat you can plaster one or two walls,
then you can't mix again until they are completely polished up.

3) have a brew, wash your trowel, bucket etc and clean the mixing
bucket 4) 10 mins later, do another mix, half the size as the first
mix. 5) apply this t-h-i-n-l-y over the now partially set first
coat, you are
only really using the new mix to fill any hollows and you will see
that it
is much smoother already than the first coat.

Again, I find its the large scale lack of flatness that is the
problem. If a hollow is smaller than the trowel,
no problem. Any it's easy to push too much plaster away so that you
create undulations in the direction of
the trowel. You can to be able to "feel" flatness under your trowel.
And I have found no magic trick to help with this.


I'm not following this? - are you mixing the plaster too stiff? - it should
have a pouring consistency....I can't think of anything in everyday life
that I could use as a comparison - certainly not as thick as ready mixed
polyfilla or tile adhesive, it should be able to drip....the only good
beginners tip I can give you on mixing is to have clean water to start with,
then sprinkle the powder in either by hand or by using a scoop...it will
disappear below the water surface until there is enough powder that no water
appears on the surface, then start mixing, either with a stick or a whisk