Hairline crack
 

What is the easiest way to seal with a hairline crack in the overskim of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)

Hairline crack
 

On Saturday, 13 April 2019 09:35:27 UTC+1, DerbyBorn wrote:
What is the easiest way to seal with a hairline crack in the overskim of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)

filler & a finger. Do not rake it out, that always makes it worse, wastes time & achieves nothing.


NT

Hairline crack
 

On Saturday, 13 April 2019 09:35:27 UTC+1, DerbyBorn wrote:
What is the easiest way to seal with a hairline crack in the overskim of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)

Probably a joint with no scrim.
If so, it will come back whatever you do.

Hairline crack
 

DerbyBorn Wrote in message:
What is the easiest way to seal with a hairline crack in the overskim of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)


Rake it out if you like, to allow filler to get down to the
bottom of the crack & adhere to each side & the base.

Filler "daubed on" with a finger tends to just rest on the
surface, doesn't adhere to the sides & falls out in short
order.

Ultimately what caused it to crack will crack it again unless
addressed.
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Hairline crack
 

On 13/04/2019 09:35, DerbyBorn wrote:
What is the easiest way to seal with a hairline crack in the overskim of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)

The last professional seeing to an issue like this widened the crack and
filled with flexible caulk to take up any movement.

Hairline crack
 

Once many years ago a bloke I knew fixed it with... Balsawood cement and a
finger.

Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
wrote in message
...
On Saturday, 13 April 2019 09:35:27 UTC+1, DerbyBorn wrote:
What is the easiest way to seal with a hairline crack in the overskim of
a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)

filler & a finger. Do not rake it out, that always makes it worse, wastes
time & achieves nothing.


NT

Hairline crack
 

On 13/04/2019 09:35, DerbyBorn wrote:
What is the easiest way to seal with a hairline crack in the overskim of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)


I paint over with PVA a couple of times to bond the crack, then, if it's
beyond what paint will fill, a smear of fine filler.

--
Email does not work

Hairline crack
 

On 13/04/2019 11:32, Tim Watts wrote:
On 13/04/2019 09:35, DerbyBorn wrote:
What is the easiest way to seal with a hairline crack in the overskim
of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)


I paint over with PVA a couple of times to bond the crack, then, if it's
beyond what paint will fill, a smear of fine filler.





I've found mixing 'polyfilla' (the powder stuff) with a mix of water and
some PVA, I guess the mix, works well- provided it isn't too wet when
applied. It is hard to sand down, so don't leave too proud.

Hairline crack
 

On Saturday, 13 April 2019 11:46:24 UTC+1, Brian Reay wrote:
On 13/04/2019 11:32, Tim Watts wrote:
On 13/04/2019 09:35, DerbyBorn wrote:

What is the easiest way to seal with a hairline crack in the overskim
of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)

I paint over with PVA a couple of times to bond the crack, then, if it's
beyond what paint will fill, a smear of fine filler.

I've found mixing 'polyfilla' (the powder stuff) with a mix of water and
some PVA, I guess the mix, works well- provided it isn't too wet when
applied. It is hard to sand down, so don't leave too proud.

Don't leave it proud at all would be more sensible :)
Plasterboard is prone to move a bit, reappearance later is fairly likely. You won't prevent that.


NT

Hairline crack
 

Brian Reay Wrote in message:
On 13/04/2019 11:32, Tim Watts wrote:
On 13/04/2019 09:35, DerbyBorn wrote:
What is the easiest way to seal with a hairline crack in the overskim
of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)


I paint over with PVA a couple of times to bond the crack, then, if it's
beyond what paint will fill, a smear of fine filler.





I've found mixing 'polyfilla' (the powder stuff) with a mix of water and
some PVA, I guess the mix, works well- provided it isn't too wet when
applied. It is hard to sand down, so don't leave too proud.


Indeed as some fillers shrink when setting/drying, leaving it
proud to sand a little is a sensible move.
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Hairline crack
 

On 13/04/2019 12:38, wrote:
On Saturday, 13 April 2019 11:46:24 UTC+1, Brian Reay wrote:
On 13/04/2019 11:32, Tim Watts wrote:
On 13/04/2019 09:35, DerbyBorn wrote:

What is the easiest way to seal with a hairline crack in the overskim
of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)

I paint over with PVA a couple of times to bond the crack, then, if it's
beyond what paint will fill, a smear of fine filler.

I've found mixing 'polyfilla' (the powder stuff) with a mix of water and
some PVA, I guess the mix, works well- provided it isn't too wet when
applied. It is hard to sand down, so don't leave too proud.

Don't leave it proud at all would be more sensible :)
Plasterboard is prone to move a bit, reappearance later is fairly likely. You won't prevent that.


NT


It takes a while if you stick some lining paper on and feather it to
blend in with the rest of the wall.

You basically paste the middle bit of the paper stick it over the filled
crack, then when dry tear it off inwards to get the feathering.
Then sand if needed.

Hairline crack
 

On 13/04/2019 09:46, wrote:
On Saturday, 13 April 2019 09:35:27 UTC+1, DerbyBorn wrote:
What is the easiest way to seal with a hairline crack in the overskim of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)

filler & a finger. Do not rake it out, that always makes it worse, wastes time & achieves nothing.


NT


Run some watered down pva into the crack first, using a small artists
bush (10 for £1 at pound shops). Capillary action will draw the
pva/water into the crack.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

Hairline crack
 

In article ,
Jim K.. wrote:
DerbyBorn Wrote in message:
What is the easiest way to seal with a hairline crack in the overskim of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)


Rake it out if you like, to allow filler to get down to the
bottom of the crack & adhere to each side & the base.

Filler "daubed on" with a finger tends to just rest on the
surface, doesn't adhere to the sides & falls out in short
order.

Ultimately what caused it to crack will crack it again unless
addressed.

I've got an old ceiling with cracks between the plasterboard. Was
originally lath and plaster, and could be the joist deflection is greater
than a modern plaster skim allows. Filled them last time with a decent
decorator's caulk, which is flexible. But also shrinks as it dries, so
took several goes to get it level. That has been successful.

--
*I got a job at a bakery because I kneaded dough.*

Dave Plowman London SW
To e-mail, change noise into sound.

Hairline crack
 

On 13/04/2019 09:46, wrote:
On Saturday, 13 April 2019 09:35:27 UTC+1, DerbyBorn wrote:
What is the easiest way to seal with a hairline crack in the overskim of a
plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate and
fill it (Creeping Crack Cure?)

filler & a finger. Do not rake it out, that always makes it worse, wastes time & achieves nothing.


NT


+1

Fine surface polyfilla, in the old days. The modern lightweight fillers
are almost as fine.

Hairline crack
 

In article ,
wrote:
On Saturday, 13 April 2019 11:46:24 UTC+1, Brian Reay wrote:
On 13/04/2019 11:32, Tim Watts wrote:
On 13/04/2019 09:35, DerbyBorn wrote:

What is the easiest way to seal with a hairline crack in the
overskim of a plasterbaord covered wall.

Do I need to rake it out or can I apply something that will
penetrate and fill it (Creeping Crack Cure?)

I paint over with PVA a couple of times to bond the crack, then, if
it's beyond what paint will fill, a smear of fine filler.

I've found mixing 'polyfilla' (the powder stuff) with a mix of water
and some PVA, I guess the mix, works well- provided it isn't too wet
when applied. It is hard to sand down, so don't leave too proud.

Don't leave it proud at all would be more sensible :) Plasterboard is
prone to move a bit, reappearance later is fairly likely. You won't
prevent that.

This is the problem, hence needing a flexible filler. That also grips well
to the board.

--
*The first rule of holes: If you are in one, stop digging!

Dave Plowman London SW
To e-mail, change noise into sound.

Electronics funny.
 

In article ,
Clive Arthur wrote:
On 13/04/2019 14:53, Dave Plowman (News) wrote:
snip

Both amp and crossover are fully enclosed in ally cases. Putting a
hand near then from any direction gets rid of the buzz. I'm thinking
to do with body capacitance. Somehow.

Are these cases grounded?

Yes.

--
*Santa Claus has the right idea. Visit people only once a year.

Dave Plowman London SW
To e-mail, change noise into sound.

Hairline crack
 

Dave Plowman (News) wrote:
In article ,
wrote:
On Saturday, 13 April 2019 11:46:24 UTC+1, Brian Reay wrote:
On 13/04/2019 11:32, Tim Watts wrote:
On 13/04/2019 09:35, DerbyBorn wrote:

What is the easiest way to seal with a hairline crack in the
overskim of a plasterbaord covered wall.

Do I need to rake it out or can I apply something that will
penetrate and fill it (Creeping Crack Cure?)

I paint over with PVA a couple of times to bond the crack, then, if
it's beyond what paint will fill, a smear of fine filler.

I've found mixing 'polyfilla' (the powder stuff) with a mix of water
and some PVA, I guess the mix, works well- provided it isn't too wet
when applied. It is hard to sand down, so don't leave too proud.

Don't leave it proud at all would be more sensible :) Plasterboard is
prone to move a bit, reappearance later is fairly likely. You won't
prevent that.

This is the problem, hence needing a flexible filler. That also grips well
to the board.


Assuming it flexes, true, but then Id expect more cracks.

A bit of silicone sealer is good for small cracks if you need it to flex.

Hairline crack
 

On Sunday, 14 April 2019 11:27:49 UTC+1, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Saturday, 13 April 2019 11:46:24 UTC+1, Brian Reay wrote:
On 13/04/2019 11:32, Tim Watts wrote:
On 13/04/2019 09:35, DerbyBorn wrote:

What is the easiest way to seal with a hairline crack in the
overskim of a plasterbaord covered wall.

Do I need to rake it out or can I apply something that will
penetrate and fill it (Creeping Crack Cure?)

I paint over with PVA a couple of times to bond the crack, then, if
it's beyond what paint will fill, a smear of fine filler.

I've found mixing 'polyfilla' (the powder stuff) with a mix of water
and some PVA, I guess the mix, works well- provided it isn't too wet
when applied. It is hard to sand down, so don't leave too proud.

Don't leave it proud at all would be more sensible :) Plasterboard is
prone to move a bit, reappearance later is fairly likely. You won't
prevent that.

This is the problem, hence needing a flexible filler. That also grips well
to the board.

Flexible filler won't solve it, the percentage of movement in a hairline crack is too large. Filling it at painting time is trivial.


NT

Hairline crack
 

Brian Reay wrote:

A bit of silicone sealer is good for small cracks if you need it to flex.

Unless you want to paint it, in which case use acrylic.

Hairline crack
 

In article ,
wrote:
On Sunday, 14 April 2019 11:27:49 UTC+1, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Saturday, 13 April 2019 11:46:24 UTC+1, Brian Reay wrote:
On 13/04/2019 11:32, Tim Watts wrote:
On 13/04/2019 09:35, DerbyBorn wrote:

What is the easiest way to seal with a hairline crack in the
overskim of a plasterbaord covered wall.

Do I need to rake it out or can I apply something that will
penetrate and fill it (Creeping Crack Cure?)

I paint over with PVA a couple of times to bond the crack, then,
if it's beyond what paint will fill, a smear of fine filler.

I've found mixing 'polyfilla' (the powder stuff) with a mix of
water and some PVA, I guess the mix, works well- provided it isn't
too wet when applied. It is hard to sand down, so don't leave too
proud.

Don't leave it proud at all would be more sensible :) Plasterboard
is prone to move a bit, reappearance later is fairly likely. You
won't prevent that.

This is the problem, hence needing a flexible filler. That also grips
well to the board.

Flexible filler won't solve it, the percentage of movement in a hairline
crack is too large. Filling it at painting time is trivial.

All I can say is it worked here. Whereas pollyfilla etc didn't.

--
*Someday, we'll look back on this, laugh nervously and change the subject

Dave Plowman London SW
To e-mail, change noise into sound.

Hairline crack
 

In article ,
Andy Burns wrote:
Brian Reay wrote:

A bit of silicone sealer is good for small cracks if you need it to
flex.

Unless you want to paint it, in which case use acrylic.

Quite. And I'd guess most ceilings are going to be painted.

--
*Why is it that most nudists are people you don't want to see naked?*

Dave Plowman London SW
To e-mail, change noise into sound.

Hairline crack
 

In article ,
Dave Plowman (News) wrote:
In article ,
Andy Burns wrote:
Brian Reay wrote:

A bit of silicone sealer is good for small cracks if you need it to
flex.

Unless you want to paint it, in which case use acrylic.

Quite. And I'd guess most ceilings are going to be painted.

I have - when younger, papered ceilings. It hides the cracks.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

Hairline crack
 

"Dave Plowman (News)" Wrote in message:
In article ,
wrote:
On Sunday, 14 April 2019 11:27:49 UTC+1, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Saturday, 13 April 2019 11:46:24 UTC+1, Brian Reay wrote:
On 13/04/2019 11:32, Tim Watts wrote:
On 13/04/2019 09:35, DerbyBorn wrote:

What is the easiest way to seal with a hairline crack in the
overskim of a plasterbaord covered wall.

Do I need to rake it out or can I apply something that will
penetrate and fill it (Creeping Crack Cure?)

I paint over with PVA a couple of times to bond the crack, then,
if it's beyond what paint will fill, a smear of fine filler.

I've found mixing 'polyfilla' (the powder stuff) with a mix of
water and some PVA, I guess the mix, works well- provided it isn't
too wet when applied. It is hard to sand down, so don't leave too
proud.

Don't leave it proud at all would be more sensible :) Plasterboard
is prone to move a bit, reappearance later is fairly likely. You
won't prevent that.

This is the problem, hence needing a flexible filler. That also grips
well to the board.

Flexible filler won't solve it, the percentage of movement in a hairline
crack is too large. Filling it at painting time is trivial.

All I can say is it worked here. Whereas pollyfilla etc didn't.


You dug it out first though didn't you?
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Hairline crack
 

On 14/04/2019 11:39, Brian Reay wrote:


Assuming it flexes, true, but then Id expect more cracks.

A bit of silicone sealer is good for small cracks if you need it to flex.

Worst piece of advice ever.

You cannot paint on silicone

If you want a flexible crack filler use decorators caulk


--
"Nature does not give up the winter because people dislike the cold."

ۥ Confucius

Hairline crack
 

On Sunday, 14 April 2019 12:11:47 UTC+1, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Sunday, 14 April 2019 11:27:49 UTC+1, Dave Plowman (News) wrote:
In article ,

Don't leave it proud at all would be more sensible :) Plasterboard
is prone to move a bit, reappearance later is fairly likely. You
won't prevent that.

This is the problem, hence needing a flexible filler. That also grips
well to the board.

Flexible filler won't solve it, the percentage of movement in a hairline
crack is too large. Filling it at painting time is trivial.

All I can say is it worked here. Whereas pollyfilla etc didn't.

With many cracks I've found their reappearance or not is unpredictable. I've not noticed the filler type make any difference, but I don't fill cracks day in day out.

Rarely I've used silicone, it works but can shrink on setting, and can't be filled a 2nd time or painted. Since it leaves a film either side of the crack that can also peel it's hardly ideal.


NT

Hairline crack
 

In article ,
Jim K.. wrote:
Flexible filler won't solve it, the percentage of movement in a
hairline crack is too large. Filling it at painting time is trivial.

All I can say is it worked here. Whereas pollyfilla etc didn't.


You dug it out first though didn't you?

I obviously dug out the old pollyfilla.

I doubt you could squeeze caulk into a hairline crack anyway.

--
*Beauty is in the eye of the beer holder...

Dave Plowman London SW
To e-mail, change noise into sound.

Hairline crack
 

On 14/04/2019 11:40, wrote:
On Sunday, 14 April 2019 11:27:49 UTC+1, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Saturday, 13 April 2019 11:46:24 UTC+1, Brian Reay wrote:
On 13/04/2019 11:32, Tim Watts wrote:
On 13/04/2019 09:35, DerbyBorn wrote:

What is the easiest way to seal with a hairline crack in the
overskim of a plasterbaord covered wall.

Do I need to rake it out or can I apply something that will
penetrate and fill it (Creeping Crack Cure?)

I paint over with PVA a couple of times to bond the crack, then, if
it's beyond what paint will fill, a smear of fine filler.

I've found mixing 'polyfilla' (the powder stuff) with a mix of water
and some PVA, I guess the mix, works well- provided it isn't too wet
when applied. It is hard to sand down, so don't leave too proud.

Don't leave it proud at all would be more sensible :) Plasterboard is
prone to move a bit, reappearance later is fairly likely. You won't
prevent that.

This is the problem, hence needing a flexible filler. That also grips well
to the board.

Flexible filler won't solve it, the percentage of movement in a hairline crack is too large. Filling it at painting time is trivial.

Which is why professionals widen the crack and fill with flexible caulk;
to reduce the percentage of movement.

Hairline crack
 

On 14/04/2019 12:18, charles wrote:
In article ,
Dave Plowman (News) wrote:
In article ,
Andy Burns wrote:
Brian Reay wrote:

A bit of silicone sealer is good for small cracks if you need it to
flex.

Unless you want to paint it, in which case use acrylic.

Quite. And I'd guess most ceilings are going to be painted.

I have - when younger, papered ceilings. It hides the cracks.

In the next few days I shall be papering the hall ceiling. The stairs
and the landing are fine and the paper can be matched. It is just that
we had a leak which damaged the hall ceiling; followed by my eldest son
ignoring my intructions to use the toilet in the small bathroom and
clambering over the blockade I'd put in the big bathroom, then putting
his foot through the ceiling where I had the boards up :(

I've just finished replacing half the hall ceiling and am waiting for
the joint filler to dry. I'd actually taken extra down to take the
opportunity to route ethernet and satellite cables through there and to
improve the run of the shower waste.

SteveW

Hairline crack
 

"Dave Plowman (News)" Wrote in message:
In article ,
Jim K.. wrote:
Flexible filler won't solve it, the percentage of movement in a
hairline crack is too large. Filling it at painting time is trivial.

All I can say is it worked here. Whereas pollyfilla etc didn't.


You dug it out first though didn't you?

I obviously dug out the old pollyfilla.

I doubt you could squeeze caulk into a hairline crack anyway.


Precisement
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Hairline crack
 

On Sunday, 14 April 2019 12:59:32 UTC+1, Fredxx wrote:
On 14/04/2019 11:40, tabbypurr wrote:
On Sunday, 14 April 2019 11:27:49 UTC+1, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Saturday, 13 April 2019 11:46:24 UTC+1, Brian Reay wrote:
On 13/04/2019 11:32, Tim Watts wrote:
On 13/04/2019 09:35, DerbyBorn wrote:

What is the easiest way to seal with a hairline crack in the
overskim of a plasterbaord covered wall.

Do I need to rake it out or can I apply something that will
penetrate and fill it (Creeping Crack Cure?)

I paint over with PVA a couple of times to bond the crack, then, if
it's beyond what paint will fill, a smear of fine filler.

I've found mixing 'polyfilla' (the powder stuff) with a mix of water
and some PVA, I guess the mix, works well- provided it isn't too wet
when applied. It is hard to sand down, so don't leave too proud.

Don't leave it proud at all would be more sensible :) Plasterboard is
prone to move a bit, reappearance later is fairly likely. You won't
prevent that.

This is the problem, hence needing a flexible filler. That also grips well
to the board.

Flexible filler won't solve it, the percentage of movement in a hairline crack is too large. Filling it at painting time is trivial.

Which is why professionals widen the crack and fill with flexible caulk;
to reduce the percentage of movement.

they do that to get paid.

Hairline crack
 

On Sunday, 14 April 2019 13:04:00 UTC+1, Dave Plowman (News) wrote:
In article ,
Jim K.. wrote:

Flexible filler won't solve it, the percentage of movement in a
hairline crack is too large. Filling it at painting time is trivial.

All I can say is it worked here. Whereas pollyfilla etc didn't.


You dug it out first though didn't you?

I obviously dug out the old pollyfilla.

I doubt you could squeeze caulk into a hairline crack anyway.

I've not met any filler that doesn't go into a hairline crack, other than coarse sand based stuff.


NT

Hairline crack
 

Fredxx Wrote in message:
On 14/04/2019 11:40, wrote:
On Sunday, 14 April 2019 11:27:49 UTC+1, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Saturday, 13 April 2019 11:46:24 UTC+1, Brian Reay wrote:
On 13/04/2019 11:32, Tim Watts wrote:
On 13/04/2019 09:35, DerbyBorn wrote:

What is the easiest way to seal with a hairline crack in the
overskim of a plasterbaord covered wall.

Do I need to rake it out or can I apply something that will
penetrate and fill it (Creeping Crack Cure?)

I paint over with PVA a couple of times to bond the crack, then, if
it's beyond what paint will fill, a smear of fine filler.

I've found mixing 'polyfilla' (the powder stuff) with a mix of water
and some PVA, I guess the mix, works well- provided it isn't too wet
when applied. It is hard to sand down, so don't leave too proud.

Don't leave it proud at all would be more sensible :) Plasterboard is
prone to move a bit, reappearance later is fairly likely. You won't
prevent that.

This is the problem, hence needing a flexible filler. That also grips well
to the board.

Flexible filler won't solve it, the percentage of movement in a hairline crack is too large. Filling it at painting time is trivial.

Which is why professionals widen the crack and fill with flexible caulk;
to reduce the percentage of movement.



....and avoid being called back or tarnishing their reputation by
being thought of as an "armchair expert" who doesn't know what
they're doing.
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Hairline crack
 

On Sat, 13 Apr 2019 08:35:25 GMT, DerbyBorn wrote:

What is the easiest way to seal with a hairline crack in the overskim of
a plasterbaord covered wall.

Do I need to rake it out or can I apply something that will penetrate
and fill it (Creeping Crack Cure?)

Captain Tollys Creeping Crack Cure is really for sealing "cracks"
that are no more than break in non absorbant materials that still
have capillary action.

Personally I follow the line of the crack with the point of a trowel,
making the crack wider and a few mm deep. Mix up some ordinary powder
filler, fairly stiff, spray the raked out crack with water to reduce
the suction, apply filler to crack with a flexible spatula filling
knife/blade, making sure the crack is fully filled. Leave very
slightly proud, layer of filler on surrounding plaster translucent
thin but not critical if there are some thicker lines from the edge
of the knife. Wait 10 mins, until the filler is partially set, wet
the flexible filling knife and smooth the the lot leaving just a
residue around. Leave to dry fully wipe of residue with damp cloth.

If the crack was caused by known movement that can't be sorted out
rather than just a random crack I'd be tempted to use decorators
caulk. Normally reserve that for timber/wall gaps, though more
recently have used powder filler as above and again fairly stiff for
that and it's not cracked,
yet...

--
Cheers
Dave.