double glazing sealant

3 Jul 2008
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United Kingdom
Hi guys, I have sealed double glazed units in hardwood window frames. Maybe 15 years old. The original sealant between the units and the frames is deteriorating. Units are good and show no misting. Sealant is not a mastic or silicone type but looks like some kind of hard dry brownish material. Any ideas what I should replace or repair it with?
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It is very possible the hard brown material you mention is butyl sealant.
this comes in tubs like putty.but should not be replaced with putty as this can cause failure of units. butyl is still available and glazed same as you would use putty.

butyl sealant years ago was the method for bedding sealed units to frames, before the use of butyl tape, same stuff in principle but comes on rolls, the units were bedded on the tape to the rebate then the perimeter of the unit would be sealed with a low modulus neutral sealant the tape put on the beads and beads fitted.

so what you could do is remove and clean beads check perimeter of unit
seal with clear low mod neutral cure sealant if req, (not assatoxic cure)as this will create its own problems to the unit.Then re fit the beads after taping with butyl tape.

or just clean beads and re bed beads on butyl from tubs.

two options hope this helps.
thanks wms, will try and get my hands on some butyl, rob
If I can't find butyl is it ok to use a silicone sealant (cartridge gun) after scraping out old stuff?
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yes but you must use low mod neutral cure to prevent the assatones in assatoxic silicon damaging the perimeter seal of the unit

Do avoid being tempted to seal the glass to the beads with silicon on the out side as when you re stain or paint it will not adhere to the sealant.

if you have a local glass merchant they should have some butyl.
I don't know if you have heard of glazing tape? very clean and strong, I buy mine from here

They do all difference thickness and width
Hi guys,

May i take the honor to ask "is it suitable for me to promot my products of butyl tape and sealants here" Thanks a million. We are a factory with more than 15 years experience in the field. Good products with good price. Website :

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