Painting spec for windows

[Roger H]

Dear all,

I'm about to replace my 20th century softwood push-out windows with some new sash windows. Softwood, double glazed. The windows at present are unglazed and primed. Can anyone advise on the method/spec for painting/glazing these. I.e. Ought the whole casement be undercoated and painted within the glazing rebates or should that just be left primed?

I had intended to putty the glazing in but am wary re issues regarding failure of DG units in contact with oils and am erring towards timber external chamfered beading to hold them in place.

Any views or advice much appreciated. The property, circa 1840 is unlisted and not in a Conservation Area. I know the windows are chunky, but the pair were £60 on ebay...

 

[Zebra]

Apologies for the terse reply, I'm supposed to be plastering, but
http://www.linseedpaintandwaxco.co.uk/
I've used theirs on mine. Breathable, organic, durable.

 

[DJH]

Here's a useful publication which can be downloaded free from

http://www.historic-scotland.gov.uk/index/learning/freepublications/publicationsresults/publicationsresultsdetail.htm?title=Sash%20and%20Case%20Windows%20-%20A%20short%20guide%20for%20homeowners

Doug

 

[Roger H]

Thanks gents. Yes, the question is not so much what to paint with, as 'Do you paint the rebates where the glazing will sit'?

 

[plasticpigeon]

Hello Roger

I hope the windows fit in their openings. Did they just happen to be the right size or were they specially made. I'm not sure about this. I think at least painting/priming the frames before glazing is the best. I would imagine that the frames you have bought do not have drip grooves or drainage channels for water to run out of. If the rebates are plain I believe that the best idea is to bed the double glazed unit in butyl putty which stays flexible and doesn't damage the seal. Then use a wooden bead bedded in butyl putty and nailed onto the sash to hold the glass in.

The best option for dg units is to have an air space all round the edge and mount the unit on spacers and then have drainage at the bottom so the seals never sit in water. If the design of the frame doesn't allow this then solid bedding in butyl is the next best option. Priming before puttying means that the wood doesn't absorb oil from the putty which would make it brittle.

 

[Roger H]

Thanks plasticpigeon - yes, they will fit snugly - Or at least will once I shave 30mm off the head jamb. An incredible fluke of size luckily as they are far from standard dimensions....

I wasn't planning on modifying building to fit




And I had been thinking of butyl mastic/putty combination as another option as would prefer this to timber beading, but wanted to pick brains on here. Appreciated.

 

[Zebra]

Thanks gents. Yes, the question is not so much what to paint with, as 'Do you paint the rebates where the glazing will sit'?

What the Holkhams eople say, they explain it on their website, is no. The oil in the paint will ruin the DG seals. You linseed oil the rebates and then shellac them, priming the rest of the window. Install your window, glaze then paint.

 

[LizE]

This could be worth a look?
Suitable for single or double glazed units and guaranteed for 10 years, can be painted or stained over.
http://uk.repair-care.com/products/dry-seal-mp

 

[Penners]

I had intended to putty the glazing in but am wary re issues regarding failure of DG units in contact with oils and am erring towards timber external chamfered beading to hold them in place.

Whether or not you use external wood beading, you should still use a putty. As a long-time hater of linseed oil putty, I now use butyl putty which I find much easier to handle. I bed the glass in putty in the rebate, then bed the wood bead in putty on the outside.

I claim no particular expertise in this, but I always paint the entire window frame - undercoat and top coat - before glazing. If I'm fitting sealed DG units, I then sit these on spacers so that they stand just clear of the bottom of the rebate.

 

[Roger H]

Thanks all. Penners, have you successfully used the holkham paints on a dg unit window?

 

[skier-hughes]

I've been using holkhams linseed paint on my d/g windows for the last 7 years now, gradually working through the house. All is good.
I have bought high quality glass units, I also painted the inner before sitting the d/g untis on spacres and holding them in with wooden beading, painted. I use a special silicon, as our d/g units are mainly self cleaning, I hate heights so going up ladders to clean windows is now a thing of the past !!

I paint all my window 3 times, fit window, fit glass, give one last coat of paint.

 

[Penners]

Thanks all. Penners, have you successfully used the holkham paints on a dg unit window?

No, Roger, I've never used Holkham Paints myself, although many on this forum have.

 

[Roger H]

Thanks all. Penners, have you successfully used the holkham paints on a dg unit window?

No, Roger, I've never used Holkham Paints myself, although many on this forum have.

Such as Skier Hughes. many thanks all. That gives me a good idea of how to approach this.

 

[Zebra]

I recommend that you download from the Holkham's website their guide on how to use their paints, including instructions for when you are having new double glazed units installed. It is important that the linseed oil paint isn't allowed to come into contact with the dg seal.

 

[Andrew Bodenham]

Roger,

I've experimented with many techniques over the years for various windows that I've made for my house, and ones that I've refurbished for customers. My preferred option is to have a timber internal bead, with the external frame chamfered to form a 'mock putty' external angle - but that won't be an option for your sashes.

I've had some good results bedding units in butyl glazing compund - although the pre-formed butyl glazing tape is a lot quicker and easier to apply. I've also used acrylic glazing putty which has the advantage of 'going off' a great deal quicker than linseed. The only place I use linseed is for fitting single glazing in wooden frames when making repairs. I never use silicone as it is impossible to paint, hard to apply neatly and seems to contaminate every surface. If I was after a really weathertight bedding compound for external beads I'd probably use Exitex Elast-o-seal, which sticks tenaciously, remains flexible and is overpaintable. The one-part polyurethane sealants sold for car body repair are also good, as are polysulphide sealants such as Arbokol. All are overpaintable, all rather difficult to apply neatly and messy to clean up - acrylic putty is easier to work with and cleans off with a damp cloth, but I don't think it is so durable.
Another option is to use the self-adhesive EDPM foam rubber sealing strip which is very quick and easy - but you do need to use robust beads and plenty of fixings to achieve sufficient compression to effect a seal.

In all cases I'd paint (or at least prime) the rebates and all faces of beads before assembly.

As for paint - well, it's a minefield. I've long since given up on 'normal' oil based gloss, and was very dissapointed with Holkhams linseed paint - it took FOREVER to dry (hopeless for windows) and quickly lost its gloss. Smells lovely though, and a joy to put on. I know that many on here are dedicated converts, but alas, not me.
Osmo ' Country Colour' has performed well on some new oak sashes that I put in a few years ago - very easy to apply, economical, microporous, one of the best things I've had out a tin. But it did take quite a few coats to cover the brown of the oak.
A recent discovery was Sadolin Supadec opaque woodstain. Looks like a very thick paint in the tin, astounding covering power, goes straight on without a primer in two or three thick coats. Quick drying, water clean up, relatively cheap, microporous. I did all my bargeboards with it last summer and after 12 months it looks like it went on yesterday. It's early days, but it gets very good reviews on decorators forums, and I'm seriously tempted to use it on my next window project. Ask me in 5 years if it's as good as I think it is.....

So there you go. Lots of ways of achieving a similar result. We all have our favourite paints, putties and goo. No doubt others will be along shortly to tell you about their favourite things in tins.

As a final PS, I can certainly say that you should NEVER use steel pins to fix your glazing beads. I've seen so many windows where the beads have failed due to the expansive corrosion of steel pins. Brass, bronze or stainless pins are easily obtained and well worth the extra few pence to make a proper job.

 

[Penners]

What an extremely useful tutorial from an expert. Thanks Andrew!