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Here's all you want to know about glazing

By Ray Lewhite

Before you start repairing a broken window, make sure you have all the materials you need. The list on this page will help you.
SAFETY NOTE You must protect your eyes by wearing safety glasses or goggles. Wear thick leather gloves when hacking out or handling glass.
First measure the frame to be glazed, measure in inches from one rebate to the other, then subtract one eight of an inch on the length and width. If you are in any doubt as to where the edge of the rebate comes, scrape away enough putty to make sure. Do get your measurements correct, and save a lot of trouble later on. Remember that not all windows are truly square, so if opposite side are equal in length, measure the diagonals of the frame. They should be equal, and if they are not, make a careful drawing of the frame, measuring all four sides.


HEIGHT FIRST

Glazing Windows
When writing down your measurements put down the height first. This is most important if you need reeded glass, for the glazer will want to know which way the flutes are to run. If you need an obscured glass, and you are not sure of the correct name, remember to take a sample with you, or take a sample rubbing as a guide. Make sure that you get the right putty for the job: Linseed oil putty for wooden frames, and metal casement putty for metal frames. Casement putty is usually coloured to distinguish it from other kinds. You will need about a quarter-a-pound of putty per foot of glass for wood frames, or one-third of a pound of putty per foot of glass for metal frames.
With all your materials together, set up your steps or ladder so that you will be working at a comfortable height, and start by hacking out the front putty with the hacking knife and hammer. Fig.1. Remove loose pieces of glass as you go, starting at the top and working downwards, with the window shut tight so you have something solid to hammer against. Having removed all the broken glass, complete the preparation by hacking out the back putty. Fig.2. Brush out the frame and sweep down the window sills, inside and out.
At this stage it is advisable to seal the wood rebates with a coat of primer or undercoat. This will prevent the oil in the putty being absorbed by the wood, considerably weakening the putty by making it dry and brittle. Any paint used must be allowed to dry before glazing is started. Painting should be omitted if you are in a hurry.
Putty must be as soft as you can use it, so if it is not soft enough knead it in some softening medium. Wipe your hands on a piece of rag, take up a handful of putty roll it into a ball and bed it into the frame (Fig.3). Keep your hands clean while performing this operation, for once putty sticks to your fingers, it will attract more, and eventually you won't be able to handle it. Keep the putty pressed in a round ball at the tips of your fingers, and if you find the putty beginning to stick to your hands, snatch it off.


BEDDING IN

Glazing Windows
Now clean your hands and press the glass in place. Never press in the middle ; always keep your hands at the sides of the glass. Give the glass a gentle preliminary push all round first, then bed well home at the bottom, followed by the sides and top. When pushing on the bottom, lift the glass slightly so that it is just clear of the bottom rebate. This will leave a very small margin of putty underneath the glass, and will help protect the glass from shock. Leave about an eighth of an inch of putty behind the glass when it is finally pushed home.
If you are glazing obscured glass the patterned surface should be indoors, leaving the smooth surface to face up on. If you are using metal casement putty, you can now bed up the front putty ready for facing off ; but if it is a wooden frame you are glazing, now is the time to fix the glass in with brads, or tingles as they are called.
Lay half-inch cobblers small headed tingle against the glass, and lay the bevel of a firmer chisel flat on the glass. Press the point of the tingle into the side rebate, slide the chisel across the surface of the glass and strike the head of the tingle with the side of the chisel. Continue striking the tingle until about one-eight of an inch is left holding the glass.
The glass is only bradded in case anyone accidentally pushes it from behind, before the putty has completely hardened, so use as few brad as possible. As a rough guide, where the frame is of a standard size i.e. 19 inch wide casements, two brads in each side will be sufficient. It is not necessary to put any top and bottom.


SPRING CLIPS

Glazing Windows
In small sashes such as fanlights, one brad either side will suffice. If the square of glass exceeds about 42 inches high or 24 inches wide, a brad or two top and bottom should be added. On metal frames, spring clips should be used if the square of glass exceeds 36 inches X 36 inches. Large squares of glass in metal frames should stand on two blocks of wood one at either end, and unless these are used spring clips should not be inserted along the bottom rebate.
Spring clips, as illustrated under materials can be obtained from your glass merchant or ironmonger. They are easiest fixed by placing the long leg of the "U" on the glass opposite one of the holes in the frame, and pushing the short leg into the hole in the frame with the aid of the putty knife (Fig.4). Clips are not needed with the smaller sizes, as the putty used hardens off in two or three days, leaving the glass quiet safe.
Now the front bedding must be put on the frame and the putty faced off. This is the same for both wood and metal frames, but more putty is needed on the metal frame as this usually has a deeper rebate. With a good bedding of putty in place, begin by placing the putty knife in the top left hand corner of the frame, the slightly rounded corner of the knife next to the glass (Fig.5). Press the knife into the angle of the frame, leaving 1/16 of a inch of the back putty showing.
With the front edge of the knife pressed against the corner of the frame, and the rounded edge touching the glass, move the knife the full length of the top rebate, maintaining the same angle throughout. Then turn the knife over and bring it back again, smoothing out the putty as you do so. Now place the knife in the top left hand corner ready to face off the left hand side, and complete this in the same way as you did the top.


SURPLUS PUTTY

Glazing Windows
Move your knife over the top right hand corner, and face off the right hand side. This time, bring the knife downwards only, leaving the return stroke until you have done the bottom. Place your knife in the bottom left hand corner, and move the knife from left to right. On completion of this action a large lump of putty will be left in the bottom right hand corner. Turn the knife over, so that the square corner is touching the glass and the end of the blade is touching the bottom rebate. The side of the blade should be now resting against the side rebate (Fig6).
Maintain the angle of the knife, keep the end and side of the blade touching their respective rebates , and slide the knife away from the glass and off the frame. This will leave you with a nice clean square corner to match the others.
Smooth the right hand side and bottom putties with a return stroke of the knife. Collect up the surplus putty that has fallen off, and brush the face putty with the dusting brush, to get the putty close up against the glass all round. Brush your putty in the same direction as you smoothed it off in your second stroke in each case. Should you be left-handed, them Im afraid you will have to reverse these instructions, substituting right for left.
The outside is now complete, so go indoors, and with the square corner of the putty knife, cut off the back putty. This is best done by starting on one side, and working up into the top corner with one movement, and then working along the top edge into the same corner. Repeat this procedure for the other corners. Brush the back putty as you did the front putty, and the glazing is complete. The window should be left for two-three weeks for the putty to harden off slightly, then a coat of paint should be applied to stop the putty weathering and cracking.
York broken window may be the top square of the bottom sash, of the counterbalanced sliding sash type. If this is the case, you will need an old steel-cored, or shatter-proof plastic handled screwdriver to hack out the top groove, which is present in this type of sash. Don't forget to allow for this groove when measuring for the new piece of glass.
Perhaps the broken glass is in your front door. In most cases it will be found that if that if the door glass has been faced up, the face putty will be on the inside. If the glass is obscure, it will be slightly more difficult to face up, as this will have to be done on the rough surface of the glass. However, the procedure is exactly the same.


SHAPED GLASS

Glazing Windows
If the door glass is shaped, there are two ways of dealing with it.
(A) Measure the opening, allow an extra inch on the shaped side, and cut the glass to shape ; or...
(B) Hack out the rebate, and cut a cardboard template to take the place of the glass (allowing 1/8in. clearance both ways). then take the template to your glass merchant, and have him cut the glass to it. (Don't forget to mark the inside or outside of the template in case the opening is not symmetrical).
If you decide on the first method, place your glass over the opening, and follow round the line of the shaped rebate with a wax crayon or candle. Remove the glass to your cutting bench, and cut on the smooth side, following the crayoned line with your cutter.
You are quiet likely to find that your glazed door has beading tacked around the rebate in place of the front putty, making a repair job much quicker. To remove the beading isert the putty knife behind one of the beads at its centre and lever the bead away from the rebate.
Continue levering until the panel pins come free, and you will find that the bead will spring out at one end. Always start with one of the longer beads, as these are more flexible and usually easier to remove.
Remove the other beads in the same way, knock out the broken glass and hack out and putty the rebate as before. When you have the glass pushed home, cut the surface putty off flush with the glass.
Take the panel pins from the beads, being careful not to damage the wood. Replace the beads beginning with one long and one short ; (e.g. the bottom and left hand side). Then take the remaining two and insert one end of each in their respective places. The other ends will protrude from the corner. Gently tap these ends with the hammer until they are partly home, then place a small block of wood over the ends, and hit this to drive the beads home (Fig.7).


NEW PINS

Glazing Windows
With a bead that is about 2ft. long the first three beads can be placed in position, then this long one can be sprung into place. Tack the beads with new panel pins and cut off the back putty. Always use new panel pins, as the pld ones often get bent. If they bend in towards the glass, breakage can quiet easily result.
When driving home the pins, place the hammer head flat against the glass as you strike the panel pin. This way there is no chance of smashing the glass. Pin the heads in 1/2in. further along than the old holes after first filling the old holes with putty.
You will probably have a bit of putty left over. Don't leave it exposed to the air to go hard, and don't submerge it in water! Seal it down in a airtight tin or jar, and it will remain supple for ages.


Fig.1a
Fig.1
Fig.2
Fig.3
Fig.4/5
Fig.6
Fig.7
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