Paint spec for renovated sash windows

[O'Chippy]

I have begun renovating many sash windows in a Victorian.
Existing paint and glazing has been removed, repairs are ongoing however I am a carpenter with little knowledge of paint and generally clueless on what finishing to use, either type or application/coats.

I've heard others argue both for and against the use of water based paints externally, a number swear only to use oil based.

The existing window joinery is largely (I believe) pine with a number of oak cills. Sash and box frame repairs will be made in accoya, cill repairs in sapele with Repaircare epoxy used where necessary.
I plan on using Repair Care Dry Seal MP, to putty in the glazing and I believe to will accept a range of paint finishes.

Given the time of year, a paint that offers quick drying time between coats would be favourable.
Also as I plan on delving into the world of spraying finishes on the interior carpentry I install, sprayed finishes are up for consideration.
I'm unsure which, if any, type of paint may tick those boxes so would really appreciate any opinions offered.


TIA

 

[meccarroll]

Hi I am also a Carpenter/Joiner...yes I hold carpentry and Joinery City and Guilds but am more proficient at site work.

I tend to use a mix of spirit based and water based paints for outdoor use. I will use a water based primer then overcoat with a spirit based topcoat. This has worked quite well in the past and tends to last about 8 years before I need to re-coat.

I have sprayed about 6 cars using cellulose paint which is a solvent based paint. You add a solvent thinner from a can to the paint and the paint dries as the solvent evaporated into the atmosphere. When spraying a car it takes a while for the solvent in the paint to evaporate so you normally apply several coats one over the other to build up the level of paint film required. You can buy Fast, Slow and anti bloom thinners for thinning cellulose paint. Cellulose thinned for spraying is fairly watery in consistency so you can use a smallish spray tip like a 1.3.

In the past, for kitchen cabinets and bedroom furniture I have sprayed acid catalyes paints. These paints are very different to cellulose in that they react with a catalist and chemically go off. They are touch dry in about 10 minutes and you can turn a cabinet door over and spray the other side in about 20-30 minutes. When I used acid catalyes paints I spray one piece at a time take it away from the spray area and then spray the next piece. I find this paint is best sprayed horizontally (lay the piece being sprayed flat) but it can be sprayed vertically to, with practice. If you try to spray too many pieces at once the overspray will land on the pieces that are chemically drying and stick to them making the finish like sandpaper. Acid cat paint often contains formaldehyde and a pungent thinner so care needs to be taken when spraying this type of paint. Both good filtered extraction (for the environment) and a very good face mask are needed for your own personal health. A/C paint gives good results that are hard wearing but does need a good setup for best results and heat too.

I am currently using water based spray paints which I have found dry rather slowly in comparison to the above so it's a new learning curve for me but less hazordous then acid catalyes paints. The water based primer that I am using has been taking around 1-2 hours to dry but thats probably because I did not use an additive to make the paint go off faster. The top coat dries in about 30 minutes but you need to take more care with water based paints as they stay soft longer than A/C paints and need to stay on a drying rack a lot longer before you can turn them to re-coat them. With the water based paints I sheet off the area I am spraying completly and add extraction to stop any overspray from entering the stacking area. I am also now using heat and exchanging the air in the drying area to help the drying process. I am going to look into water based paints in more depth in particular the additives for speeding up drying times and the water based paints that dry faster to. One thing to note about water based paints is they are thicker then A/C paints so you need a larger tip to spray them say a 1.8 to 2.5.

There are othe paints such as PU which are said to be very good at drying and hold a very tough finish but you need to be very careful about spraying most PU paints as they mostly contain isocyanate which can be very harmful to you and anyone that comes into contact with it. There are some PU paints that do not contain isocyanate but you need to be very careful in selecting a safe paint for youyou and your setup.

For spraying I would advise looking into spraying with a Turbine and HVLP spray gun or a compressor with a minimum 14 CFM of output and a HVLP spray gun. Good quality HVLP spray guns give reduced overspray so less paint is used on the panels you spray. The HVLP spray guns used with compressors generally need a mimimum of around 9.5-12.5 CFM for best results you probably need a compressor with a minimum of 14 cfm for constant results.

A good Turbine with HVLP spray gun will help reduce overspray and reduce paint usage so saves money on wasted paint.

 

[O'Chippy]

@meccarroll Thanks for the extensive response, certainly lots to consider.
ATM between this major renovation project and family life I have a lot on my plate and realistically won't be able to commit much brain power to in-depth learning of the various spraying options and considerations, from reading some of your posts and others there is much to consider.
For this particular project should I choose to spray the solution would have to be no more complex than >buy this tin of paint of the shelf>pour into this handheld sprayer>spray and walk away.
Completely understand that this particular strategy may be costlier and result in a lesser quality finish but life ATM dictates finding a method that gets the job done.

Have you any comment on the cordless Graco or Wagner cordless sprayer?
I'm on the DEwalt platform therefore as the Graco uses Dewalt batteries in amy be a good option but I its expensive and I cannot seem to find it sold as a bare unit.

 

[RobinBHM]

I plan on using Repair Care Dry Seal MP, to putty in the glazing and I believe to will accept a range of paint finishes.

have you any experience with using it?

I ask as it is not easy to use at all.

Ive done dozens of sashes with it and its pretty horrible to use -it is like trying to get a smooth finish with sticky decorators caulk

you might want to consider rapid set putty or normal putty.

 

[O'Chippy]

have you any experience with using it?

I ask as it is not easy to use at all.

Ive done dozens of sashes with it and its pretty horrible to use -it is like trying to get a smooth finish with sticky decorators caulk

you might want to consider rapid set putty or normal putty.

Haha, never used it but its promoted as being the opposite as you've experienced hence my consideration of it.
Actually I think its main selling point is it can be painted over soon after application, although
I unsure if in practice that is useful or not.

I've nothing against using putty, mostly because I have never used it before either.
I've never had great results with mastic so perhaps putty is the better option for me.
Great to hear feedback from actual users of these products in the field 👍

 

[deema]

Just from experience, I’ve found water based paint to be the stuff of the devil. It forms a hard shell that cracks, water gets under and rots the wood. First time you know is when a hole appears. You can’t burn / heat gun off, so your down to trying to sand back to bare wood. Oil based paint every day, or Linsead oil based paint (wrong time of year needs sun to harden and very slow drying).
I have HVLP but just started playing with airless. Finer finish with HVLP, but airless is far easier and perfect for finishing wood. You can spray anything straight out of the can without diluting with the right airless / air assisted airless. Not much overspray, in fact my very limited experience suggests less than my HVLP.

 

[meccarroll]

For this particular project should I choose to spray the solution would have to be no more complex than >buy this tin of paint of the shelf>pour into this handheld sprayer>spray and walk away.
Completely understand that this particular strategy may be costlier and result in a lesser quality finish but life ATM dictates finding a method that gets the job done.

Have you any comment on the cordless Graco or Wagner cordless sprayer?
I'm on the DEwalt platform therefore as the Graco uses Dewalt batteries in amy be a good option but I its expensive and I cannot seem to find it sold as a bare unit.

Ok, but when you start spraying if you don't take the time to prep the area, dust, spiders flies etc may land on your paintwork. If you do spray try to use a paint that has a relatively short drying time or use an additive to speed up the drying that way dust flies etc have less time to spoil your work.

I have not used any cordless paint sprayers but Graco and Wagner both have good reputations in the paint world. My HVLP spray gun is a Wagner gun and very good. Graco also produce some very high end HVLP guns too.

I would say the battery operated guns are more aimed for site use rather than mass spraying. If you buy a battery spray gun make sure it can use different sized tips for different paints or at least match the gun tip with your intended paint.

Solvent based paints are generally sprayed thinner than water based paints. Solvent around 1.3 and water based around 1.8 to 2.5. Check out the gun literature and make sure the gun can handle the paint you intend using.

I am not a paint sprayer or claim in any way to be an expert related to spraying but I have and do use spray equipment and the better you prep the work area, your equipment and plan ahead the better the results.

Buy some paint strainers for your paint, measuring cups, tack cloths and a gun filter for the paint these will help prevent contamination of the sprayed paint. Silverline Stearated Aluminium Oxide Rolls from ebay are good for sanding down and if you use them in a Makita palm sander can save a huge amount of time when sanding between coats. You can buy cheap paint strainers and measuring cups from Alixpress or ebay. Tack cloths help remove stubborn films of dust etc from after sanding and the gun paint strainer adds protection from particles in the paint landing on the finished surface.

 

[Jacob]

I've done acres of (single) glazing with ordinary linseed oil putty and once you've got the hang of it it's easy, a pleasure to use and very cheap.
Best to prime bare wood rebates with knotting first, or old stuff including painted, with linseed oil.
Can be useful to soften putty with a quick blast in the microwave - just a few seconds.
Takes time to go off but can be painted once surface touch dry.
Lasts for 100 of years given good maintenance.
I got into linseed oil paints a few years back and now wouldn't use anything else for outside work. Expensive by the tin but but very good coverage and fast/easy to apply. Seems to stick to anything, bare wood, old paint, metalwork. It's very different from modern paints but fast and easy once you get used to it.
n.b. never use sprigs or pins except as temporary fixings if necessary - remove when putty has gone off enough, before finishing. No need for them at all on small panes.

 

[O'Chippy]

I've done acres of (single) glazing with ordinary linseed oil putty and once you've got the hang of it it's easy, a pleasure to use and very cheap.
Best to prime bare wood with knotting first, or old stuff including painted, with linseed oil.
Can be useful to soften putty with a quick blast in the microwave - just a few seconds.
Takes time to go off but can be painted once surface touch dry.
Lasts for 100 of years given good maintenance.
I got into linseed oil paints a few years back and now wouldn't use anything else for outside work. Expensive by the tin but but very good coverage and fast/easy to apply. Seems to stick to anything, bare wood, old paint, metalwork. It's very different from modern paints but fast and easy once you get used to it.
n.b. never use sprigs or pins except as temporary fixings if necessary - remove when putty has gone off enough, before finishing. No need for them at all on small panes.

Good to hear sprigs/pins are necessary, I have about 20+ panes of old thin glazing to refit and was concerned that at least one would suffer the wrath of the Estwing.

Yes I read that it is essential to prime bare wood prior to putty, otherwise the oil is drawn out of the putty and drys it perhaps?
Is there a specific linseed oil to use for this, would either boiled or raw versions suffice?

 

[O'Chippy]

Just from experience, I’ve found water based paint to be the stuff of the devil. It forms a hard shell that cracks, water gets under and rots the wood. First time you know is when a hole appears. You can’t burn / heat gun off, so your down to trying to sand back to bare wood. Oil based paint every day, or Linsead oil based paint (wrong time of year needs sun to harden and very slow drying).
I have HVLP but just started playing with airless. Finer finish with HVLP, but airless is far easier and perfect for finishing wood. You can spray anything straight out of the can without diluting with the right airless / air assisted airless. Not much overspray, in fact my very limited experience suggests less than my HVLP.

I'm unsure if you have seen Jim Sears sash window restoration videos on youtube, he too considers water based paint useless on sash window, externally at least.

 

[Jacob]

Good to hear sprigs/pins are necessary, I have about 20+ panes of old thin glazing to refit and was concerned that at least one would suffer the wrath of the Estwing.

typo? not necessary. Except once doing some small pane windows on a hot day close up to a main road with steep hill and lots of passing HGVs (Cromford Hill), the putty softened in the heat and the vibrations made it run (thixotropic) and had to redo with one or two sprigs each pane.

Yes I read that it is essential to prime bare wood prior to putty, otherwise the oil is drawn out of the putty and drys it perhaps?
Is there a specific linseed oil to use for this, would either boiled or raw versions suffice?

I'm told that raw gets absorbed better. But it takes longer to dry. You can still putty over it when not perfectly dry. Knotting is good in rebates too.

 

[O'Chippy]

typo? not necessary. Except once doing some small pane windows on a hot day close up to a main road with steep hill and lots of passing HGVs (Cromford Hill), the putty softened in the heat and the vibrations made it run (thixotropic) and had to redo with one or two sprigs each pane.

I'm told that raw gets absorbed better. But it takes longer to dry. You can still putty over it when not perfectly dry. Knotting is good in rebates too.

Haha, yes that was a typo.

 

[Ollie78]

Tikkurila otex adhesion primer then valti ultra topcoat.
Not sure how well it will spray with your system but it is what I use when renovating sash windows and brush it onsite.
I have sprayed the Otex a couple of times and it goes on well but I have a Kremlin eos.
I have used Morrells Omnia on new joinery with reasonable results but for me the Otex primer is the best. I really didn`t like the Teknos one that I tried, its like jelly and refused to flatten nicely, left an orange peel effect no matter what I tried.

Do not bother with the extra expense of the Dryseal, or any products from Repair care they are just taking the p**s.
I have been using the Timbabuild stuff from chemfix for years but just started using Oxera repair resins which are very good so far and much better prices.
Hodgsons Heritage putty is just as good as dryseal and considerably cheaper, Timbaglaze is ok as well, the 3c sealants one is acceptable and cheap but I dislike the Oxera one as it is too sloppy and takes ages to skin over.
As some have mentioned there is a knack to applying this type of hybrid polymer putty, use a Palu tooling block (the same as dryseal use ). You can get a decent finish once you get the gist of it, do a bit of practice.

 

[O'Chippy]

Tikkurila otex adhesion primer then valti ultra topcoat.
Not sure how well it will spray with your system but it is what I use when renovating sash windows and brush it onsite.
I have sprayed the Otex a couple of times and it goes on well but I have a Kremlin eos.
I have used Morrells Omnia on new joinery with reasonable results but for me the Otex primer is the best. I really didn`t like the Teknos one that I tried, its like jelly and refused to flatten nicely, left an orange peel effect no matter what I tried.

Do not bother with the extra expense of the Dryseal, they are just taking the p**s. Hodgsons Heritage putty is just as good and considerably cheaper, timba glaze is ok as well, the 3c sealants one is acceptable but I dislike the Oxera one as it is too sloppy and takes ages to skin over.
As some have mentioned there is a knack to applying this type of hybrid polymer putty, use a Palu tooling block (the same as dryseal use ). You can get a decent finish once you get the gist of it, do a bit of practice.

Great information Ollie thanks for sharing.
My local decoration merchant has been pitching me Zinsser primer and Zinsser Allinone for under and top coat. You seem well informed, so I was wondering if have you any opinion on these products for sash windows? Regardless I will research the paints you have suggested.

I suppose with putty work I should try the various option incl linseed putty and see which my hand takes best to. I have a few obsolete sashes to practice on.

 

[deema]

@Ollie78 have you had to repaint any windows that have been painted with your suggested paint? The reason I ask is to understand how easy it is to prep. If I’ve read it correctly the top coat is water based, my arch nemesis to prepare!
Very nice airless sprayer you have, did you start with it or move up to it from another brand?

 

[Ollie78]

Great information Ollie thanks for sharing.
My local decoration merchant has been pitching me Zinsser primer and Zinsser Allinone for under and top coat. You seem well informed, so I was wondering if have you any opinion on these products for sash windows? Regardless I will research the paints you have suggested.

I suppose with putty work I should try the various option incl linseed putty and see which my hand takes best to. I have a few obsolete sashes to practice on.

In my experience Zinsser paints are very good and I have used the all in one myself. I would say it is not quite as good as the Tikkurila but better than most.
The Otex primer really is good, covers stains, really sticks well, denibs very well and dries very quick for an oil based product.

I know some people love the linseed oil putty and it can be perfectly fine and is cheap (also i love the smell of it). If you do use linseed oil putty one of the best advice I can offer is to dust it off properly.
This means get a little tub of plaster and a brush ( I prefer a round sash brush) dip the brush into the plaster and brush around all of the putty LIGHTLY brushing plaster dust over it along the length. This removes extra oil, helps to make sure it is bonded to the glass nicely and helps it start to dry

I think hybrid polymer is a better choice because it remains flexible so won`t crack, it actually bonds the glass in, it is certified for use with double glazed units and accoustic laminated glass ( at least Hodgsons is ). You can actually leave it unpainted if you want, though I normally paint topcoat over it if I am doing the painting. Also birds and rodents don`t like to eat it unlike putty which they will snack on happily .

 

[RobinBHM]

there is nothing wrong with water based paint and if you want to spray, its the only realistic option

Ive used Teknos, Omnia, Sigma, Remmers and others

these paints are all made from the same base components however some set harder than others, in my experience those developed in sa Italy set harder........they arent as flexible and in our damp climate they are likely to crack at joints

Teknos is one of the softest paints, and pretty good

however for someody not in the trade the easiest to get hold of and good prices are the Mighton paints which come from Holland, Anker Stuy Verven BV. Ive sprayed this paint a number of times and its pretty good, also quite soft and flexible


One of the most important factors in longevity of external paint finishes is the design of the joinery: modern joinery has 3mm radiuses no outside edge, joints are made with a V, and careful consideration is given to avoiding water trapping............but none of those features are going to be applied to heritage work, so a soft, flexible water based paint is best


If you want to spray, use an airless gun like graco or dewalt, you need a 4-11 tip, thin the paint a little bit.

the biggest failure of water based joinery coatings is winter curing.........these paints need 12 deg+ to cure and will literally take weeks and weeks to cure in the winter and they are vulnerable to blistering and peeling. its best left until its warm, as they then cross link quickly

 

[O'Chippy]

In my experience Zinsser paints are very good and I have used the all in one myself. I would say it is not quite as good as the Tikkurila but better than most.
The Otex primer really is good, covers stains, really sticks well and denibs very well and dries very quick for an oil based product.

I know some people love the linseed oil putty and it can be perfectly fine and is cheap (also i love the smell of it. if you do use linseed oil putty one of the best advice I can offer is to dust it off properly.
This means get a little tub of plaster and a brush ( I prefer a round sash brush) dip the brush into the plaster and brush around all of the putty LIGHTLY brushing plaster dust over it along the length. This removes extra oil, helps to make sure it is bonded to the glass nicely and helps it start to dry

I think hybrid polymer is a better choice because it remains flexible so won`t crack, it actually bonds the glass in, it is certified for use with double glazed units and accoustic laminated glass ( at least Hodgsons is ). You can actually leave it unpainted if you want, though I normally paint topcoat over it if I am doing the painting. Also birds and rodents don`t like to eat it unlike putty which they will snack on happily .

In my experience Zinsser paints are very good and I have used the all in one myself. I would say it is not quite as good as the Tikkurila but better than most.
The Otex primer really is good, covers stains, really sticks well and denibs very well and dries very quick for an oil based product.

I know some people love the linseed oil putty and it can be perfectly fine and is cheap (also i love the smell of it. if you do use linseed oil putty one of the best advice I can offer is to dust it off properly.
This means get a little tub of plaster and a brush ( I prefer a round sash brush) dip the brush into the plaster and brush around all of the putty LIGHTLY brushing plaster dust over it along the length. This removes extra oil, helps to make sure it is bonded to the glass nicely and helps it start to dry

I think hybrid polymer is a better choice because it remains flexible so won`t crack, it actually bonds the glass in, it is certified for use with double glazed units and accoustic laminated glass ( at least Hodgsons is ). You can actually leave it unpainted if you want, though I normally paint topcoat over it if I am doing the painting. Also birds and rodents don`t like to eat it unlike putty which they will snack on happily .

Thanks Ollie, just wondering when you say to dust the putty of with plaster, what particular plaster are you referring to, gypsum multi-finish?

 

[Ollie78]

@Ollie78 have you had to repaint any windows that have been painted with your suggested paint? The reason I ask is to understand how easy it is to prep. If I’ve read it correctly the top coat is water based, my arch nemesis to prepare!
Very nice airless sprayer you have, did you start with it or move up to it from another brand?

Can`t say I have had to repaint any that I have topcoated with the Ultra but I do know what you mean about water based paints being harder to prep.
I would say that if you were to scuff it well and do a coat of Otex primer that will give a good start, that stuff will stick to a plastic drainpipe.

The Kremlin is my first air assisted airless machine but before that I have used all the other types of spray gear. It really is the best spraying device I have ever used, very little over spray, great spray pattern, the gun is nice to use, you don`t need to thin the paint.
The only disadvantages are you don`t really just want to spray one small item because you have to clean and flush all the hoses out so you waste a good bit of paint like that, and parts like tungsten nozzle and filters are quite expensive.

 

[O'Chippy]

there is nothing wrong with water based paint and if you want to spray, its the only realistic option

Ive used Teknos, Omnia, Sigma, Remmers and others

these paints are all made from the same base components however some set harder than others, in my experience those developed in sa Italy set harder........they arent as flexible and in our damp climate they are likely to crack at joints

Teknos is one of the softest paints, and pretty good

however for someody not in the trade the easiest to get hold of and good prices are the Mighton paints which come from Holland, Anker Stuy Verven BV. Ive sprayed this paint a number of times and its pretty good, also quite soft and flexible


One of the most important factors in longevity of external paint finishes is the design of the joinery: modern joinery has 3mm radiuses no outside edge, joints are made with a V, and careful consideration is given to avoiding water trapping............but none of those features are going to be applied to heritage work, so a soft, flexible water based paint is best


If you want to spray, use an airless gun like graco or dewalt, you need a 4-11 tip, thin the paint a little bit.

the biggest failure of water based joinery coatings is winter curing.........these paints need 12 deg+ to cure and will literally take weeks and weeks to cure in the winter and they are vulnerable to blistering and peeling. its best left until its warm, as they then cross link quickly

Thanks Robin, very happy to hear advice on spraying.
Interesting to hear you say that water based paints are the only realistic option for spraying. I haven't research in any detail but I though the Graco ultra max can spray oil based paints (the max model in particular). Perhaps its just that water based lends itself better to spraying?

Given the point you made regarding drying times, its another vote for using oil based paints this time of year.