Another great tip from the MSN Groups Caravan forum on how to refit a window.

You will need the following:

• silicone – architectural type
• hand full of nozzles
• silicone gun
• snap knife
• paper towels
• masking tape (MMM not cheap stuff)
• spray bottle of soapy water (dish washing detergent)
• silicone square (cost $2 and is worth it)
• acetone
• scarring pad
• backing rod if needed

Clean the surfaces with the pad, knife and paper towel using acetone. Your bead will want to have contact with at least 10mm on both surfaces (glass and frame). Use the masking tape to make a line on the glass of where you want the bead to end. Best to have an angle of the silicone bead going up the glass of 45 degrees or less otherwise the edges will peel off the glass later. You can also mask the frame side but unless your really messy this should not be needed.

If the gap is too deep (more than 15mm or so you should fill it with backing rod to the required depth). Backing rod should be wider than the gap so it holds to the the sides of the gap, push it in far enough to create the required depth. You might need to cut the backing rod length ways if you only have a shallow area to fill.

Cut your nozzle at the angle you are going to hold the gun and to the width of the gap, opps? bet you are glad you grabbed those spare nozzles?. Pump the silicone into the gap until it starts to come back up out of the gap. A good run will show little ripples raising up behind the the nozzle as you move the gun along. Do not worry about your bead at this stage even the messiest application will tool off to a good finish just remember it is better to use too much than too little silicone.

Now you have the silicone applied spray it all over with the soapy water including the surrounding frame (silicone will not stick to soapy water). This is where the silicone square pays off but if you didn’t get one use some plastic, I have made one out of an empty silicone cartridge before. Holding the square at an angle run it along the bead level with the bottom of the masking tape, you are not only removing the excess silicone you are also forcing it into the gap, this is called tooling off. When the square starts to get full wipe it off onto the paper towels.

Peel off the tape and you will have a good seal. If your application was good there will only be a thin line of silicone on the tape on the other hand if the tape is loaded no problem just use the knife to cut the tape so you can remove in manageable sections.Any minor defects can be poked with your fingers if you spray them first with soapy water or in an emergency you can use spit. If you have a major mishap don’t worry wait until it cures (will say how long on the tube, could be days). Cut the offending section out with your snap knife (you are able to have a longer blade than with a stanley knife). No need to clean the surfaces silicone sticks just fine to silicone, repair seal using the same process above.