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Seeking best practices to maintain/restore 1965 Andersen casement windows


Betty 01730's Avatar
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09-06-17, 02:06 PM   #1  
Seeking best practices to maintain/restore 1965 Andersen casement windows

I am a new owner of a 1965 home with original Andersen casement windows in need of TLC. Unlike double-hungs, I am stumped by these beautiful windows. I seek advice on best practices to keep them another 50+ years.

Chemical tests indicate that the interior finish is a non-poly varnish. Exteriors are latex paint.

PROBLEMS:

--Interior:

Most windows need sand & varnish touch-ups. Should I use a drying oil before varnish? If so, is tung better than BLO?

--Exterior:

Right now, most windows need a bit of touch-up. In the next few years, perhaps 5-8 sashes should be removed for stripping exterior and refinishing. Should I stick with latex paint for exterior?

Help from the community much appreciated.

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marksr's Avatar
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09-06-17, 02:14 PM   #2  
I'd sand and apply a fresh coat or two of varnish or poly on the interior side. If there are any offensive water stains you might need to use some wood bleach on them.

On the exterior, coat any raw areas with an oil base exterior wood primer. Top coat with a quality latex house paint.


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Betty 01730's Avatar
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09-06-17, 05:32 PM   #3  
Thanks, marksr, for your input.

Just want to confirm--you do not see any benefit to using a drying oil first on the exposed wood?

I'm not trying to be difficult. It's just that I have been researching this question for a while--primarily because I have no expertise or footing here. There is a lot of info out there, and for me, it doesn't all add up. Maybe if you have more input you can help me be confident in my actions.

I have found several videos and sites that advocate restoring old windows, and sometimes, the posters get pretty passionate about using BLO on the stripped window. Like, 2 thinned coats.

A subset of this group that cares about old windows advocates using nothing but BLO-based paints over the BLO-treated wood. They even advocate painting right over the not-yet-cured BLO. Their argument is that the materials and construction of windows has a proven track record that goes back 600 years.

Then, among wood-worker sites, I read that BLO has a risk of growing mold, and tung oil is better.

There is another school of thought (Mr. Flexner-GREAT BOOK!): the "old school" coatings were not used because they were so stellar but because they were available. Considering this, one ought to avail oneself of the newest technologies, such as latex paint and polyurethane varnish. More importantly, Mr. Flexner advocating fitting the finish to the use.

Hopefully, you now see why I have more questions. Thank you in advance for your patience! -MLH

 
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09-07-17, 02:31 AM   #4  
I don't know what you mean by drying oils or BLO
I've been painting since the 60's, professionally since the 70's.

Varnish and poly basically do the same thing but poly has a harder [longer lasting] finish. Varnish was an improvement on the older softer shellac finishes. For the most part oil base finishes are harder than latex. That means it will withstand wear better. On the exterior latex coatings are better at withstanding the elements. An oil base primer will seal the wood better and in the case of old chalky paint - it will bind up and adhere to the chalk [always best to remove what you can first] Latex primers don't bond well to chalk and don't totally seal raw wood.

Years ago if a house had bare weathered dried out siding we might apply a coat of linseed oil [cut in half with thinner] before applying the primer. I've never done so on interior wood. Both linseed oil and oil base paints are more prone to mildew than latex paints.


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09-07-17, 02:52 AM   #5  
Ahhh, I'd never heard it referred to that way. BLO=Boiled Linseed Oil

The other per Wikipedia "A drying oil is an oil that hardens to a tough, solid film after a period of exposure to air. The oil hardens through a chemical reaction in which the components crosslink (and hence, polymerize) by the action of oxygen (not through the evaporation of water or other solvents). Drying oils are a key component of oil paint and some varnishes. Some commonly used drying oils include linseed oil, tung oil, poppy seed oil, perilla oil, and walnut oil. Their use has declined over the past several decades, as they have been replaced by alkyd resins and other binders."

And I agree with Mr Flexner. It's what they had ATT. Even in a historically accurate restoration (and sorry 1965 isn't considered "historical"), they wouldn't use milk paint or lime wash except in those that were required to be absolutely accurate with a no-limit budget.

Just about the cheapest vehicle you can buy now is more reliable and will last longer than just about anything from back then, right? Same with lots of other things, including exterior coating.


Vic
"I sometimes wonder how some people ever made it to adulthood..."

 
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09-07-17, 03:04 AM   #6  
Thanks for the info Vic! I never thought of boiled linseed oil as a drying oil but rather a coating to add 'moisture' to the wood so when the primer was applied the extra dry wood wouldn't [say that real fast] dry too fast. If linseed oil is applied without thinning it takes forever for it to dry. Primers that dry too fast tend to set on top of the wood instead of soaking in and getting a deeper bond.


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