6708 13 l1_121_presentation_3
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Transcript of 6708 13 l1_121_presentation_3
Level 1 Diploma in Plastering
© 2013 City and Guilds of London Institute. All rights reserved.
PowerPoint
presentation
Methods of providing a key to backgrounds
Unit 121: Prepare background surfaces and mix
plastering materials
Level 1 Diploma in Plastering
© 2013 City and Guilds of London Institute. All rights reserved.
Assessment criteria
1.5 describe the importance of forming a key and using
bonding agents to background surfaces
2.5 provide key and bonding agents to backgrounds
surfaces
Level 1 Diploma in Plastering
© 2013 City and Guilds of London Institute. All rights reserved.
Forming a key means
creating a rough surface to
improve its adhesion.
Forming a key for plaster
is one of the most
important jobs a plasterer
can do. Failing to provide
a key will result in bond
failure and the plaster
falling off the wall.
Forming a key
Level 1 Diploma in Plastering
© 2013 City and Guilds of London Institute. All rights reserved.
Skutch hammer
This hammer can be used to apply a
key to smooth background such as
dense concrete.
Mechanical stripping tools
You can also provide a key using
attachments for a 110V stripping tool.
Mechanical key
www.youtube.com/watch?v=EzWd40dIrYI
Level 1 Diploma in Plastering
© 2013 City and Guilds of London Institute. All rights reserved.
Raking out joints
This process means that
you cut out a recess in
the brickwork mortar
joint. When you have
raked all the joints, you
can plaster the wall; the
plaster grips in the
raked-out joint.
Mechanical key
Level 1 Diploma in Plastering
© 2013 City and Guilds of London Institute. All rights reserved.
Raking out joints
This can be done by hand using a pick hammer or by
using a hand-held 110v grinder. There are also
specialist tools on the market made solely for the
purpose of raking out.
Mechanical key
www.youtube.com/watch?v=OHBPl5TqJsk
Level 1 Diploma in Plastering
© 2013 City and Guilds of London Institute. All rights reserved.
Spatterdash/slurry/stipple
coats
A coat used on dense
backgrounds to form a key.
This helps the plaster to
bond to the wall.
Chemical bonding agents
Level 1 Diploma in Plastering
© 2013 City and Guilds of London Institute. All rights reserved.
Polyvinyl acetate
Commonly referred to as PVA,
this is applied by a roller or
brush and is mixed 1 part PVA
to 5 parts water.
PVA must be tacky when
applying plaster; it seals the
background giving even
suction and helps plaster to
adhere to the wall/ceiling.
Chemical bonding agents
www.specifinder.com/brochures/3013_pdf6.pdf
Level 1 Diploma in Plastering
© 2013 City and Guilds of London Institute. All rights reserved.
PVA
Can be used on a variety of backgrounds, including:
• old plastered walls
• Thermalite blocks
• textured coatings
• painted surfaces.
Note: the more porous the surface, the more PVA you
will have to apply in order to kill the suction.
Chemical bonding agents
Level 1 Diploma in Plastering
© 2013 City and Guilds of London Institute. All rights reserved.
ThistleBond-it
High quality bonding agent
especially made for the
plastering industry.
• Apply with a roller or
brush
• Green in colour so you
can see missed spots
• Has a grit added so
plaster adherers
• Plaster 24 hours after
application
Chemical bonding agents
Level 1 Diploma in Plastering
© 2013 City and Guilds of London Institute. All rights reserved.
ThistleBond-it
Can be applied on:
• dense smooth surfaces
• painted surfaces
• stone.
ThistleBond-it is the most practical
background treatment on the
market, as it eliminates any suction
problems you may find.
Chemical bonding agents
www.british-gypsum.com/products/ThistleBond-it