Working the 'fat'.

[joe-90]

Why do people throughout the plastering world think there is 'fat' in plaster?
Fat is an ingredient in cookery - not plastering.

Fat in plastering refers to 'surplus' as when you are talking about the 'fat of the land'. It doesn't refer to some ingredient that is added to the plaster after in comes out of the furnace.

So why do you do it?

 

[1john]

Just a guess, but could be the same reason that chippies think there are birds mouths in rafters and sparkys think there are currents in cables......??

 

[Micilin]

Why do people throughout the plastering world think there is 'fat' in plaster?
Fat is an ingredient in cookery - not plastering.

Fat in plastering refers to 'surplus' as when you are talking about the 'fat of the land'. It doesn't refer to some ingredient that is added to the plaster after in comes out of the furnace.

So why do you do it?

Are you serious , joe?

When you trowel up finish and get a bit left on your trowel, or over work a bit of finish, use too much water you get a lighter coloured bit plaster with different properties It does not have grain it in, it takes longer to set and is not good for filling holes as it is weaker -it has been 'killed' (now please don't think it has been murdered ) .

That is why you don't fill misses in walls with it, as you see the fat marks and trowel marks in the wall when it is set. Poor plastering will show loads of lighter coloured bits , lines and trowel marks in it, even if it is otherwise flat.

If you are napping render, you bring up a bit of fat to the surface (this is where the lime comes in) to give you the napped texture.

Have you heard of 'mud' before? I sincerely hope you don't' think this means using sodden earth!

 

[Micilin]

Just a guess, but could be the same reason that chippies think there are birds mouths in rafters and sparkys think there are currents in cables......??

Or that 'Site Managers" actually 'Manage' the site

 

[Richard C]

I seem to remember joe & RC having a similar discussion some time ago which, I believe, invloved RC plastering his watch into the wall.

 

[trowelmonkey1]

Just a guess, but could be the same reason that chippies think there are birds mouths in rafters and sparkys think there are currents in cables......??

 

[NickB_99]

Poor plastering will show loads of lighter coloured bits , lines and trowel marks in it, even if it is otherwise flat.

Sorry to hijack the thread Joe

I was doing a spot of plastering last night after work, and Micilin's comment
made me think.

From looking at the pic from last night's wall, is this a high level of fat?

Untitled

• NickB_99
• 11 May 2010
• 1

Dining Room corner

It is reasonably flat, tho I wouldn't say perfect, but there are no obvious trowel marks.
Always keen to improve!

 

[noseall]

What you need to understand is that joey could have an argument in an empty room!

When referring to 'fat', the same terminology is used in laying concrete and describes the liquid suspension that works its way to the surface whilst working the material you are laying.

The only differences are that in plastering it is regarded mostly as a waste product but in concreting it is quite useful.

 

[Micilin]

It is reasonably flat, tho I wouldn't say perfect, but there are no obvious trowel marks.
Always keen to improve!

As long as it's flat, no problem. You'll find that the fat might shrink a bit, or if it is used to fill a biggish hole, you can pick at it with a finger . Don't worry about it too much, your wall looks fine and you'll get a few different shades as it dries anyway.

 

[roy c]

What you need to understand is that joey could have an argument in an empty room!

When referring to 'fat', the same terminology is used in laying concrete and describes the liquid suspension that works its way to the surface whilst working the material you are laying.

The only differences are that in plastering it is regarded mostly as a waste product but in concreting it is quite useful.

If my memory serves me well (which it doesn't usually ) the "scum" on top of concrete is called "Lattice"

 

[marshman]

[quote="DIYnewbee99";p="1610094
Always keen to improve! [/quote]

Get over it earlier and keep your trowel flatter so you fill them.