PRACTICAL
Resealing the glazing into the frames
A
s a dry-run, first
reassemble the glass
into the frames with the
fishplates fixed on one side only,
and determine how much
channel-chocking rubber is
needed by inserting it into the
frame channel base around the
glass perimeter to provide about
1-2mm of movement of the glass
within the frame. This may take
several attempts, and is likely to
involve either single or double
thicknesses of rubber: ensure
they are cut generously to hold
themselves tightly in place.
For the channel-base perimeter
chocking rubber, cut the rubber
strip into 8-10mm-wide blocks the
(tight) width of the channel and
about 1cm long, using a caliper
depth gauge as a template guide to
ensure lengths are accurate. Fit to
the frame as necessary. Check
against your stencil of the original
frame size and make sure any
cramping leaves some movement.
Try to ensure the glass is central
and clear of the fishplates. I drew a
quick ‘chocking’ diagram for each
frame, which proved a useful
reference when one or two of the
earlier frame chocks dropped out
during handling before application
of the butyl. When satisfied with the
fit, do a final assembly by putting
some butyl sealant bedding
compound onto the cleaned
fishplates and mitre joints then
screwing together. The frame can
be left overnight, then cleaned up
with a blade dipped in white spirit.
Starting now with chemically clean frames and windows, it’s time to start reassembling everything.
Drawing a quick ‘chocking’ diagram for each frame may well prove invaluable as a reference source
The chocking rubbers in place in
the base of the channel We drew a rubber chocking piece diagram for the glass and framesCutting the chocking rubbersA fishplate covered in sealant,
prior to assembling a frame
Filling the face side with two-pack
butyl, using a strong rotating actionPressing the glass down created
a new void all around the frame
Smoothing a radius into the
butyl edges with a knifeFor the internal glass face
chocking rubber, cut short lengths
of rubber about 5mm wide and the
depth of the channel less about
4-5mm, so when the glass is
inserted it will be supported in its
internal vertical face but have
sufficient ‘cover’ of butyl glazing
sealant. I added the number of
chocks per side and spacing to the
chocking diagram: a useful guide
later when inserting the butyl.
Use a small (say ½in) brush to
apply primer to the inside and
outside faces of the frame/glassinterface, then set aside for over 30
minutes (but less than 8 hours)
prior to filling the frame with
two-pack butyl. This butyl has one
black and one white component, in
our case 1kg each. The white is like
a dryish putty and can be cut easily,
but the black component is rubbery
and deforms before it cuts. I
therefore found it easier to measure
these by weight before mixing.
Wearing gloves, mix these stiff
components in equal quantities by
twisting and kneading until the
marbling becomes a consistent
black colour: no need to rush, it
cures in days rather than hours.
Lay the frame down with the
outside face up and firmly insert the
butyl into the frame, using a strong
rotating action to maximise
pressure until it can be seen filling
the bottom channel of the frame.
Clean off the excess. Turn the frame
over, face down, and carefully press
the glass down to create a newvoid all around the frame into which
the internal vertical face chocking
rubber is inserted at intervals of
roughly 75-125mm. These are
pressed in below the frame edge
but still support the glass: make
sure they don’t rotate by using a flat
rather than rounded pushing tool.
If you have done the ‘face-up’
butyl filling properly these will bed
into the butyl at the bottom of the
channel. Now force butyl into this
side, working around the frame and
taking care not to create voids, then
chamfer/radius the edges to lap the
frame using any convenient tool or
knife (clean-up is done some days
later). Turn the frame over and
chamfer/radius the face-side butyl.
While the butyl is fresh, check the
frame dimensions against the stencil
of the original frame and cramp if
necessary. Set the frames to cure,
undisturbed, in a warm place for at
least a week before cleaning with a
soft cloth and white spirit.The frame was cramped to the original dimensions on the stencil