Glazing sealant for wood glazing bars

[600rob]

Im replacing the some of the wooden glazing bars on my conservatory that have rotten.

Ive also got a few where what ever was used to seal the bars has failed resulting in water getting down the back of the glazing bar.

whats the best sealant to use when refitting the new bars and sorting out the existing ones?

Was considering dow 799 but cant see anything to suggest it bonds well to wood?

Anyone got any suggestions?

 

[HERTS P&D]

See below:

http://www.geocel.co.uk/catalogue/s...glazing-frame-weatherproofing/dow-corning-791

Andy

 

[600rob]

Cheers Andy

 

[opps]

I use MS polymers such as TimbaBuild glazing.

No idea which part of middlesex you live in but the Leyland SDM in Ealing Broadway has them on special, IIRC it is 2 tubes for a tenner. However you will need to buy a skeleton gun with a higher thrust ratio. It is quite thick.

Alternatively CT1, Stixall, etc., will work with standard guns.

The product that Andy linked to is a good product but you can't paint over silicone. That said, if you use a ms polymer, you will probably need to prime it with waterbased undercoat first, I have experienced oil based undercoats remaining tacky for weeks if waterbased hasn't been used first.

I would also add that MS polymers are less forgiving when it comes to application than silicones. Use the cheap blue tape at toolstation to prevent the risk of the sealant going all over the glass, and then remove the tape as soon as you apply the sealant.

 

[foxhole]

You can’t beat a high thrust rate !!

 

[opps]

You can’t beat a high thrust rate !!

My, bad, that should have been "high thrust ratio"

 

[ronniecabers]

Whatever you use make sure that on the tube it says Low Modulus Neutral Cure. Anything else will eat away at the sealed unit sealant and the sealed units will not last . As for the likes of Stixall ... If you ever need to get those beads of without destroying them I really wouldn't!

 

[opps]

Hi Ronnie

I am looking at things from my perspective (ie as a decorator).

I am not, intentionally disagreeing with your advice, but can you recommend a paint that adheres to silicone? As a professional decorator, I find myself wasting a lot of time explaining why I am spending sooooooo much time cutting away the clear silicone bfeore i paint the windows.

You are correct- Stixall is pretty rigid. I have however managed to use oscillating saws to cut through it without damaging anything.

Perhaps, I should have over recommended CT1, if only for the fact that it remains far more flexible than Stixall or the TimbaBuild.

With regard to "eating" the seals. None of the above are solvent based and the TimbaBuild specifically states that it is suitable for double glazed units.

 

[ronniecabers]

Opps you are correct in that paint does not adhere to silicone, It is a messy glazier who gets silicone all over the beads ( which I appreciate some DIYers may be messy as put it through lack of experience with silicone guns....as a company we don't use just silicone , we use Hodgsons Flexistrip , a butyl flexible putty like strip, that expands and contracts, as it never sets rigid ( https://www.reddiseals.com/product/butyl-tape-sealant/ ) . It is perfectly safe to paint over too. In my honest opinion, the correct way to glaze a wooden frame with a sealed unit would be to put the ' Flexistrip ' flat on the back beads ( Its sticky so will stay there, and it can overlap within the visible glass area ) remove the backing tape, then place your sealed unit in, making sure it has adhered fully to the ' flexistrip' , fill the void between the frame and sealed unit with a Neutral cure Low Modulus clear silicone, then a second layer of 'flexistrip' on the glass unit , where the beads will be sitting ( with practice it becomes easier to see exactly where the beads go without having to use the beads as a template ) , then push each bead onto the flexistrip , again making sure it has adhered , then pin the beads in. Any excess ' flexistrip ' can be trimmed off with a sharp stanley Knife ( only makes of knives are available! ) . Job done and Painter / decorator can paint bead and flexistrip if needed ( comes in off- white and brown so doesn't always need painting. We have been using this method for the best part of 25 years . The only time it may be different if if you have ' dry glazing ' , which is were the bottom bead has packers under it , and sits proud of the frame , creating a drip. No silicone should be required there , as the frame should drain any water out if manufactured and installed correctly

 

[opps]

Thanks for the comprehensive answer ronniecabers.

I don't have an account with Reddieseals but a friend does. Will have a look at the products that you recommended.

Cheers

 

[600rob]

we use Hodgsons Flexistrip , a butyl flexible putty like strip, that expands and contracts, as it never sets rigid ( https://www.reddiseals.com/product/butyl-tape-sealant/ ) . It is perfectly safe to paint over too. In my honest opinion, the correct way to glaze a wooden frame with a sealed unit would be to put the ' Flexistrip ' flat on the back beads

Thanks for this ronnie,

on dismantling my windows from the wood frames it appears they were fitted with an epdm tape similar to this
https://www.reddiseals.com/product/epdm-tape/

I was going to use an epdm tape on re-installation in combination with a LM neutral sealant, after reading your post though i might use butyl tape instead.