Painting original wooden windows - absolute beginner needing help!

[Harveya]

Hi,

Apologies for the simplicity of this question.

New to the forum and after scouring the internet for hours and finding so much conflicting information is anyone able to offer some simple advice please.

I'm painting interior and exterior windows of our Edwardian house with original windows (after having our carpenter come and exclude any rot in them etc) and am at a loss as to what products to use.
1. Should I be using linseed putty? If so, as it has such a long drying time can I use it outside? what if it rains?
2. Do the windows need putty inside as well as outside?
3. What can I use to fill any gaps in the wood before I paint?
4. Depending on the answer to Q1, if using linseed putty should I be using an oil based primer followed by an oil based paint?

if anyone can recommend any brands of putty/paint they'd recommend or any other tips/video's that would be fab.

Your advice would be much appreciated!

 

[Tilly71]

Watching this post also for advice!
I believe linseed putty is good for external repairs as allows to breathe.
I’m seeing advice elsewhere that oil based paints for traditional windows should be swapped for any breathable paints.

 

[malcolm]

You've got modern waterproof gloss paint on there at the moment. It cracks and lets water in and the water can't get out again so the wood rots. I think modern waterproof wood paint is the invention of the uPCV window manufacturer demons.

A lot of us have original windows that are hundreds of years old. Those windows have survived because they could dry out when they got wet. They were painted in linseed paints and gaps were filled with linseed putty which are breathable coatings.

There is a debate on here about the exact paint that is best. I've stripped my windows back to wood and am continuing with the linseed putty and paint for the low maintenance. Others use breathable water based paints for improved initial durability and quicker drying time.

Linseed putty takes years to fully dry but can be over-painted once it skins over in a few days.

 

[overlander matt]

A few years ago Bedec MSP was very popular with a few of the contributors here. I used that on the 20 or so windows here but I would be keen to know whether its durability compares well with other paints. It's 4 years now since we painted our windows and a few are looking a bit shabby. I was only planning on a light sand and touch up coat on the worst sections - mainly the sills. What would be a typical expectation for having to recoat previously restored windows?

 

[Tilly71]

For filling internal cracks / holes in traditional wood windows, can you use linseed putty or a standard powder based filler?

 

[Lacan07]

For filling internal cracks / holes in traditional wood windows, can you use linseed putty or a standard powder based filler?

For internal I would use standard wood filler

 

[Zebra]

The filler to use depends on the paint to use. If using linseed paint, use linseed putty. If using water based paint (e.g. Bedec MSP), use a water based filler indoors, or for best performance you can use a two-part epoxy filler (I just learned on here that two-part epoxy wood fillers are exactly the same as two-part epoxy car body fillers so I have used car body filler!)
I am right in the middle of the linseed paint versus Bedec MSP debate. I did all the windows in the linseed paint 10 years ago, and it had become flaky and grubby. I have sanded half of the windows back to bare wood and done in the MSP, and half of them repaired the flaky bits with linseed oil paint again, so I will let you know in a few years which performs best.
The advantage of the MSP is the drying time - the durability, we will see, though others on here say that once switched from linseed oil paint to MSP they haven't looked back.

 

[fernicarry]

Those are really quite crusty looking. Have they been painted shut? The bottom left corner of the right window looks a bit dodgy to me, maybe give it a prod with something pointy and see how it feels.

Best to start by dismantling to get the sashes out of the frames. This will mean removing the staff and parting beads which you can think of as consumable but check you can buy matching replacements before starting. New beads will have draft-proofing brush strips in them so they will perform better too. This will let you replace the cords and possibly the pulleys too.

Assuming everything is in good enough condition to be worth continuing, I think I'd want to strip back to bare wood to have a chance of a decent finish. If you try to sand the existing coatings you'll have craters everywhere as some bits of paint flake off but other bits resolutely stick in place. No point in spending time and money on new paint unless its going onto a sound surface.

I fill the gaps between separate elements with a mastic like Soudal SDS i.e. between the window board and the frame etc. This allows for a bit of seasonal movement which is inevitable. Internal defects on the surface you can fill with any old wood filler. Externally its a bit more tricky, the two part fillers that claim to be usable externally don't really last any length of time. You'll find threads on here discussing products if you do decide to use filler. I had a fairly simple binary choice, my top sashes were mostly original to the house and perfectly sound after 160 years, the bottom sashes were mostly modern soft pine replacements and went in a skip without even trying to repair them so I've not really had to use filler externally. I did fill the bottom rail on one of the modern replacements but its obviously still soaking wet and I don't think it has much life left in it.

2. Do the windows need putty inside as well as outside?

There will be a thin layer of putty visible from the inside between the glass and the rebate. Its the same putty bed that the glass was bedded into when fitted and like the external putty it will harden and fall apart. This allows condensation running down the window to run into the rebate and rot the bottom rails from the inside out. Dig out loose hard bits and then push fresh putty firmly into the gap. This especially important on the top sash as its often too high up to see clearly and can be a right state. If the external putty fillet has failed too you might be best removing the glass altogether and bedding it into fresh putty.

Tbh you are in for a lot of work but they will look fantastic once refurbished.

 

[mardinor]

Here’s the paradox. Your wood will be better than you can buy new, so worth repairing. But modern materials are far better than old ones in this application. Linseed oil takes too long to dry and attracts mould on horizontal surfaces. Linseed putty cracks and lets water in behind the paint. Oil paint doesn’t last as well as water based these days since they changed the formulas. Learnt the hard way on all of these.

Look at the RepairCare system for external filling and ‘puttying’. And a good water based paint such as Jotun Demidekk or Bedec MSP. Both are expensive but they work and last several times longer than alternatives. I’ve used them to repair all my 150 year old sashes.

Well done for keeping them. If you’re an eco nut you can add secondary glazing and/or floor length thermal curtains and shutters to give better overall performance than double glazing. Or just enjoy the breeze and fresh air like I do.

 

[Georgeonthecrescent]

There will be a thin layer of putty visible from the inside between the glass and the rebate. Its the same putty bed that the glass was bedded into when fitted and like the external putty it will harden and fall apart

@fernicarry I have the same question regarding puttying on the inside and out.

I have read a few articles and they say different things. Some say to lay the glass on a bed of putty and then apply another layer of putty externally. Others say to lay the glass directly on top of the rebate and push the external putty into any gaps.

Previously in my window there was a a good 5mm of putty between the glass and rebate but most of it was cracking, and the finish was very uneven.

Also, should the external putty be visible from the inside, or should it be a thin enough bead so that it’s hidden entirely behind the rebate?

Thanks!

 

[fernicarry]

Some say to lay the glass on a bed of putty and then apply another layer of putty externally. Others say to lay the glass directly on top of the rebate and push the external putty into any gaps

You should put the putty bed on the rebate first, fit the glass into it, then add the external fillet. On an old window the rebate will be a bit crusty so you're not going to get a good seal laying the glass straight onto it. If using modern sealed units then its done with glazing tape in the rebate and usually a wooden glazing bead applied to the outside.

Previously in my window there was a a good 5mm of putty between the glass and rebate

I have one window where the glass is quite bowed. I guess being cylinder glass this particular piece didn't end up completely flat so the putty bed is pretty substantial in places to make up for that. More typically its just 1-2 mill.

Also, should the external putty be visible from the inside, or should it be a thin enough bead so that it’s hidden entirely behind the rebate?

The external fillet ends just before the inside of the rebate so that when you paint the outside the paint isn't visible from the inside. The paint should overlap slightly onto the glass to form a seal.

 

[Georgeonthecrescent]

Thank you. That’s very very helpful

 

[Georgeonthecrescent]

I’ve hit a bit of a snag though. The rebate at the top of the lower sash is ‘internal’. So there is no place for the putty to hide. Any ideas?

 

[CliffordPope]

"The external fillet ends just before the inside of the rebate so that when you paint the outside the paint isn't visible from the inside. The paint should overlap slightly onto the glass to form a seal."

The outside paint is always visible from the inside if you view the window from an angle of more than 45 degrees.