# Should I paint before fitting windows



## garethharvey (3 Jul 2017)

Struggling a little with this one, I am replacing our glasshouse, the last one has pretty much rotten and all the paint failed. This time I am using Western Red Cedar which is also more substantial on the size.

Should I pain the units prior to fitting or should I fit then paint. I am thinking the end grain of the units will possibly rot. Alternatively, is there something I should put on the eng grain? I am using linseed oil paint


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## Jacob (3 Jul 2017)

Paint after, not before. 
Everything out of sight should be paint free. Especially bottom edges - if not then paint seals moisture in and you can end up with bottom rails getting waterlogged and rotting. 
On the other hand linseed oil paints are more breathable than any modern paints so the advice to prime first before installation, with linseed oil only , is probably good. But definitely not paint first - this gives you a handling problem amongst other things; waiting for it to dry and would all need touching up etc.


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## Phil Pascoe (3 Jul 2017)

I've not known any windows I've ever made or fitted to rot, and I've always soaked them in a good preservative, primed and undercoated all round before fitting, then undercoated and glossed after fitting. If the weather turns vile and you don't get back to them for months you don't have too much to worry about. How is the moisture to get in if they are painted all round and maintained?
I've taken a whole load of rotten ones out that haven't been painted all round.


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## Jacob (3 Jul 2017)

phil.p":33gk7vzz said:


> ..... How is the moisture to get in if they are painted all round and maintained?.....


They'd have to be _perfectly_ maintained to keep moisture out. But sooner or later paint fails, especially at joints, putty lines etc and water gets in. I've taken out modern frames which have been literally waterlogged along the bottoms - painted underneath and not helped by being set on mortar beds instead of having an air gap.
Whereas all the trad stuff I've ever removed, sometimes 100 years old, shows no sign of paint anywhere unnecessary and out of sight.


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## Phil Pascoe (3 Jul 2017)

And all the trad stuff I've removed has been rotten.  I agree with the point about their sitting in a bed of mortar, though.


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## garethharvey (3 Jul 2017)

Thanks Guys, my main concern in the mitres on the cill, there are 8 in total. Would I seal the cill with silicone or anything when fitting?


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## Beau (3 Jul 2017)

phil.p":3qvrtfbw said:


> I've not known any windows I've ever made or fitted to rot, and I've always soaked them in a good preservative,



Not made loads of windows and most have been stained not painted but would definitely recommend a good soaking in clear wood preserver before painting.


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## Phil Pascoe (3 Jul 2017)

Be careful putting silicone anywhere that has to be painted - better to find another flexible filler that can be overpainted.


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## Phil Pascoe (3 Jul 2017)

Beau":344rl578 said:


> phil.p":344rl578 said:
> 
> 
> > I've not known any windows I've ever made or fitted to rot, and I've always soaked them in a good preservative,
> ...



I should actually have said I soak the parts before assembly. The joints then are in with a chance. I regularly pass a garden gate I made nearly 25 years ago that's still immaculate - it's made of (commercially) untreated whitewood.


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## Beau (3 Jul 2017)

phil.p":3evw75a8 said:


> Beau":3evw75a8 said:
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> > phil.p":3evw75a8 said:
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I have not gone that far but have put the finished windows and frame upright in a tray of preserver so it can soak deep into the wood. Does soaking it before glueing not make the joints expand and mess up the joint fit?


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## Phil Pascoe (3 Jul 2017)

It seems to make little difference. I soaked the parts in that instance for about two weeks then allowed them to dry for about the same before assembly - it wasn't noticeable then that anything had been done to them at all. I have done everything that way ever since.


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## ColeyS1 (3 Jul 2017)

I always send stuff out with 2 coats of aluminium primer before it leaves the workshop. Everything gets two coats before any glass gets fitted. - Thats using oil based paints though. Perhaps it's different for linseed paint.
Coley 

Sent from my SM-G900F using Tapatalk


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## RobinBHM (3 Jul 2017)

We paint on end grain sealer to any cill ends, end of stiles on doors etc.

Cills have their edges radiuses with an approx 3mm rad on top and front edge. the mitre ends are sealed with end grain sealer. The cills are then joined with MS polymer sealant which is also used in the V formed by the radiused edges.

Generally it is good practise to avoid a sharp 90 degree sawn edge at joints or any other edge. If for example a tightly jointed cill is painted over, if the cill expands and ocntracts then it could crack the paint at the joint. A 3mm radius on all edges mean paint flows around the radius and the film thickness is maintained. If unseen faces are not painted then the same applies


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## Phil Pascoe (3 Jul 2017)

ColeyS1":3hu53nd6 said:


> I always send stuff out with 2 coats of aluminium primer before it leaves the workshop. Everything gets two coats before any glass gets fitted. - Thats using oil based paints though. Perhaps it's different for linseed paint.
> Coley
> 
> Sent from my SM-G900F using Tapatalk



I worked a while ago with a very good joiner who wouldn't price for jobs that weren't to be coated in preservative, primed and white undercoated. He'd had too many complaints about his work rotting, shrinking, expanding ... when people had fitted it for a few years without getting around to painting it.


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## Jacob (3 Jul 2017)

phil.p":3uxwjv86 said:


> ColeyS1":3uxwjv86 said:
> 
> 
> > I always send stuff out with 2 coats of aluminium primer before it leaves the workshop. Everything gets two coats before any glass gets fitted. - Thats using oil based paints though. Perhaps it's different for linseed paint.
> ...


Yep you need belt and braces with modern paints - plus preservatives, plus very regular maintenance. They are all cr*p. Linseed oil paints utterly superior "Allback" and other brands


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## Phil Pascoe (3 Jul 2017)

I doubt linseed paints would have been any better if they weren't used.


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## Jacob (3 Jul 2017)

phil.p":36srcwvn said:


> I doubt linseed paints would have been any better if they weren't used.


er - what? 

Oh I see what you mean - if they weren't used for regular maintenance. Actually if used from the beginning they are amazingly durable even if not maintained. Won't last forever but will certainly do better than any modern paints.


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## RossJarvis (4 Jul 2017)

Having done a fair amount of re-painting over the past couple or three years, the main reason exterior wood rots out is due to lack of maintenance and poor initial preparation. Poor design is also a factor. I'm not convinced that linseed oil paint is substantially better than modern paint, but I wouldn't be surprised if it was.

As some have said, treating the wood before or after assembly will help, but I don't think this was done 100 years ago and some of those windows are still sound and good redwood is the same as it was then. Any exposed end grain should be sealed. Only the exposed areas need painting as proper construction should keep the rest dry. There shouldn't be any sharp edges (arrises) either., 3mm radius is the current spec but in the past all arrises would be relieved and not left sharp which may have only been a mm or so. Whatever paint to be applied should be selected for it's longevity and will probably be a system which should be followed to the letter. After that the paint should be checked every year, particularly at joints and recoated regularly, 3 years is the standard time for a re-coat even for most modern paints and few if any can last beyond 8. I usually hear "it was only done 5-8-10 years ago"

When I were a lad every year all the neighbours would be out checking or doing the painting over the summer, nowadays people generally think of repainting when the old paint is falling off, which is after it's too late. I'm currently repainting the woodwork on my brother's house and as expected found the exterior doors had not been painted on the bottom. Most "Professional" painters these days generally don't know much about painting so I doubt whether much new woodwork since 1980 has been painted well and I dare say it's similar for a lot of modern joinery construction.


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## AndyT (5 Jul 2017)

Not sure if it's relevant with modern waterproof glues, but plenty of old books up to about WW2 say that for exterior work you should paint all the joint faces before assembly.


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## garethharvey (5 Jul 2017)

Thanks, I know where I am going with this now, will be coating all the cills with wood preserver, paining the Cill end grain with end grain treatment.

Will assemble the glasshouse before painting, will leave the bottom of the Cill unpainted for water to escape. I have made all the mortice and tennon joints all the way through so water can also escape.

Primer for linseed oil paint is just pure linseed oil. Am I right in thinking this can all be painted with the raw oil prior to assembly?


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## Jacob (5 Jul 2017)

RossJarvis":2hjjlean said:


> Having done a fair amount of re-painting over the past couple or three years, the main reason exterior wood rots out is due to lack of maintenance and poor initial preparation. Poor design is also a factor. I'm not convinced that linseed oil paint is substantially better than modern paint, but I wouldn't be surprised if it was.


I'm convinced - I've been using both for 50 years and the superior performance of linseed is beyond doubt for me. I now don't use anything else (externally) - I've seen too many failures of modern paints. 
Strictly speaking modern linseed oil paints are 'modern' but have very much in common with the old paints - except for having no lead (and some other toxic substances). They can be touched up after a few years with just more linseed oil.
The big difference in a nut shell is that modern paints are very durable in themselves but don't always stick to the wood - water gets in behind and the paint lifts off - the flakes still in good condition as they fall to the floor and the woodwork rots! Hence the need for preservatives.
But linseed oil weathers and deteriorates from the surface, not from behind - so it looks dull but stays firmly stuck for years , until the last traces are washed off. No lifting, flakes or cracks, so can be touched up or covered again with oil alone or paint, at any time, after a bit of a wash down if necessary


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## RobinBHM (5 Jul 2017)

> But linseed oil weathers and deteriorates from the surface, not from behind - so it looks dull but stays firmly stuck for years , until the last traces are washed off. No lifting, flakes or cracks, so can be touched up or covered again with oil alone or paint, at any time, after a bit of a wash down if necessary



virtually all joinery manufacturers use water bourne microporous paints now. They dont harden like the traditional alkyd based gloss paints. These water based products dont suffer oxidisation which hardens alkyd based products, they stay soft. Weathering causes the surface of the paint to erode, so the film thickness gradually reduces -in line with comments above about linseed paints

The key to minimise re-decoration cycles is to design the joinery to allow water shedding, avoid water trapping and capillary action issues as well as avoiding sharp corners. 

Whilst Im sure linseed paint is a great product, it isnt practical for a joinery manufacturer to use it. 

Modern paints arent carp, but to achieve extended time between decoration cycles requires all the elements to work together; good joinery design, correct application of end grain sealer, correct painting techniques to achieve optimum coating thickness, correct storage and treatment on site and correct fitting ensuring all end grain cuts are properly sealed etc.

Usually when problems with paint peeling or other faults appear it is automatic to blame the paint, when in fact its often a combination of faults leading to paint cracking and peeling.


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## ED65 (5 Jul 2017)

RobinBHM":3bt005lr said:


> Usually when problems with paint peeling or other faults appear it is automatic to blame the paint, when in fact its often a combination of faults leading to paint cracking and peeling.


Ditto with glue. Almost everyone blames the glue when there's a failure and often they look for a 'better' replacement (as seen in threads here and every other woodworking forum I read) when most of the time it's down to a problem with materials or a failure in method.


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## Jacob (5 Jul 2017)

ED65":gr08lazf said:


> RobinBHM":gr08lazf said:
> 
> 
> > Usually when problems with paint peeling or other faults appear it is automatic to blame the paint, when in fact its often a combination of faults leading to paint cracking and peeling.
> ...


If I follow the instructions on the can and other sources, use well known branded supposedly good quality materials, and it still peels, then I blame the paint. I've seen it happen too often in too many different circumstances.
Actually it's glaringly obvious - thorough application of timber preservative is more or less standard nowadays. This means one thing; the paint is no good on its own.


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## Jacob (5 Jul 2017)

RobinBHM":jmqvuvfa said:


> ...
> 
> Whilst Im sure linseed paint is a great product, it isnt practical for a joinery manufacturer to use it.....


Why not?


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## garethharvey (5 Jul 2017)

Jacob":2tqto5r3 said:


> RobinBHM":2tqto5r3 said:
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Probably due to the time it takes to dry.


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## RobinBHM (5 Jul 2017)

> If I follow the instructions on the can and other sources, use well known branded supposedly good quality materials, and it still peels, then I blame the paint. I've seen it happen too often in too many different circumstances.
> Actually it's glaringly obvious - thorough application of timber preservative is more or less standard nowadays. This means one thing; the paint is no good on its own.



Im making a comparison with professional supply exterior paint made for joinery and its application for joinery. We have excellent technical back up from our paint supplier and notes on how to detail joinery and fitting. 

If paint fails at joints, mitred glazing beads, mitred cills, sharp edges or where timber parts are butted together for example where a trim may be cut to a cill then they are all areas where incorrect detailing has caused the coating to fail, not a fault of the paint itself.

A typical example is where paint cracks at the junction between the bottom rail of a door and the stile. The rail is wide so a significant movement occurs and the paint cracks at the joint line, eventually moisture gets in, wicks along the rail end grain and paint starts peeling. 

Linseed paint couldnt be used for joinery manufacture, too slow to dry, not suitable for spraying, probably too soft for delivery and installation.


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## Jacob (5 Jul 2017)

RobinBHM":3hyr99t7 said:


> ......
> A typical example is where paint cracks at the junction between the bottom rail of a door and the stile. The rail is wide so a significant movement occurs and the paint cracks at the joint line, eventually moisture gets in, wicks along the rail end grain and paint starts peeling.


Not if it's linseed. It doesn't peel and it floods cracks, keeping moisture out.


> Linseed paint couldnt be used for joinery manufacture, too slow to dry, not suitable for spraying, probably too soft for delivery and installation.


Yes you might have to change your work routines! Is too soft for delivery and installation and has to be painted in situ, though can be primed in the shop.


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## Phil Pascoe (5 Jul 2017)

Surely priming defeats the object?


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## garethharvey (5 Jul 2017)

phil.p":2hoc8sud said:


> Surely priming defeats the object?



Not all woods require a primer with this paint, the primer however, is raw linseed oil.


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## Jacob (5 Jul 2017)

garethharvey":2np3bl8x said:


> phil.p":2np3bl8x said:
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Yes primed with oil. Best if warm and in a warm workshop. Very easy to apply, very easy to clean, no VOCs, no solvents required, nothing toxic.


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## ED65 (6 Jul 2017)

Jacob":5m36lppy said:


> ED65":5m36lppy said:
> 
> 
> > RobinBHM":5m36lppy said:
> ...


That's fair enough within reason. But you're tarring modern paints with a very wide brush here. All other things aside no matter how many windows you've personally painted that's a very small sample group. We don't know if 75% of other users of the same paints had much better experiences (for a host of reasons we can only speculate about).

You're going by what you've seen with your own eyes which is fair enough. But I can give a counterexample that I've seen with my own eyes from the family home. It is only a single case but it shows that modern paints aren't all cr*p (your exact words) and don't _always _crack or flake or peel, even after zero maintenance for ~20 years. Instead the paint weathered down in just the way that you described linseed paints do a few posts above, while I can guarantee that that isn't what was used. 



Jacob":5m36lppy said:


> Actually it's glaringly obvious - thorough application of timber preservative is more or less standard nowadays. This means one thing; the paint is no good on its own.


That's one interpretation. Another is they're taking a belt-and-braces approach _based on known failure modes of wooden windows_. 

The thing is this knowledge base goes way back because since at least the 70s DIY books have been advising to use preservative or sealer on end grain where possible and the implication of this can't be over-emphasised in this context: the rotted windows they were basing the advice on would go back to a time when linseed oil paints were still common, if not ubiquitous.


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## Jacob (6 Jul 2017)

ED65":2p8y0oyt said:


> .......
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> Jacob":2p8y0oyt said:
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I'd amend this to; "known failure modes of wooden windows _painted with modern paints_" 
Preservatives only started being used routinely fairly recently, from the 70s as you say. Old joinery seems to survive very well without it - unless totally neglected for a very long time, or until stripped and painted with modern paint, which is the kiss of death!


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## ED65 (6 Jul 2017)

By definition those were old windows painted with old paints, so I reject that amendment


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## RossJarvis (7 Jul 2017)

I think the main problem is with the painting not the product. Modern paints are very good and in many respects much better than linseed oil paints, particularly in regard to finish and colours, but nobody wants to put the effort into proper maintenance.

Even with older paints, including linseed oil, there came a time to strip back to bare wood, you can't just keep on painting on top of paint, at some time there'd be more paint than wood. This used to be between 10-15 years. So prime properly, undercoat and top coat. every three years rub down and re-coat. after 10-20 years strip back to bare wood and start again. At the very best today you could expect to re-coat after 8 years.

What really happens? The joinery turns up and even if the joiner has said what the primer is and paint regime should be, the painter slaps on whatever he has in the van., if lucky the process is controlled and a correct system is followed. In my experience, more than often, one top coat is applied. When it comes to repainting, people select someone on price and go for the cheapest, which is someone who may wipe down with a rag and then slap on a single coat of whatever the client wants. On a job I did a couple of years ago the painter was recommended on how quick he worked, particularly as he did no prep.

I've never known paint to flake or peel if done properly, only if something has gone wrong (not always obvious to the user). Two main problems are painting over badly prepared/deteriorated paints, or using a non compatible paint system over something else. Unfortunately the data sheets given by manufacturers don't really cover all the essentials.

The days have now gone where people realised you need to strip back to the wood regularly, so I'm fairly sure the days of long lasting woodwork have gone. That's why I recommend plastic joinery over wood, I don't like it but it'll last longer with neglect than wood will.


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## Jacob (8 Jul 2017)

RossJarvis":1u2yzv0m said:


> ....
> Even with older paints, including linseed oil, there came a time to strip back to bare wood, you can't just keep on painting on top of paint, at some time there'd be more paint than wood. This used to be between 10-15 years. So prime properly, undercoat and top coat. every three years rub down and re-coat. after 10-20 years strip back to bare wood and start again. At the very best today you could expect to re-coat after 8 years.


Not sure if this is true. I started enthusiastically stripping my grandparents joinery many years ago. A victorian house in Nottingham. It rapidly became obvious that it had never been stripped before and I was removing the accumulation of 100 years of paint - which was in fact in excellent condition but just a bit thick around the mouldings etc. It was also extremely difficult to do (3 bay sash windows, half a ton of lead paint etc) and obviously pointless. 
I think paint work was cleaned down and touched up with very thin coats (linseed oil paints don't work if too thick) and never stripped back. Hence the longevity - once stripped and repainted the life of the woodwork would be drastically reduced.
Since then I've worked on hundreds of bits of old joinery and basically never encountered the tell tale signs of stripping - burn marks on the wood.It was never done.


> .....
> I've never known paint to flake or peel if done properly, only if something has gone wrong (not always obvious to the user).


That's what is called a 'truism'. The question is - have you known paint to flake or peel (I certainly have) when paint does peel is it the fault of the paint or the painter? I've learned to blame the paint.

PS about incompatibility - they don't recommend it but I've found that linseed oil sticks brilliantly to other defective paints - and also seems to stabilise it - floods into cracks and soaks into bare wood. So no need to strip back - just brush off loose stuff and sand back to a nice edge. It may not work with all paints of course.


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## garethharvey (8 Jul 2017)

My house was build in 1904, we have quite a decorative bit of woodwork just under the 2nd floor. I stripped this back to the bare wood in 2015, this was the first time it had ever been stripped back. There was minimal pain on there. I would estimate this had been painted once every 20 odd years.

The quality of the wood is as good as it was when it was put in place 113 years ago. I would argue that this would would not have survived 113 years with modern paints.


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