Wood Pre-Treatment before priming

johnleeke
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Wood Pre-Treatment before priming

Postby johnleeke » June 6th, 2011, 3:54 pm

This has been submitted for inclusion in the Standards:

Install one coat of a mixture of 60% paint thinner and 40% boiled linseed oil. Allow to completely dry for one to three days depending on humidity and temperature. This treatment puts resins back into the wood fibers. Extremely dry wood sucks the binder out of the oil base primer causing the primer to lift off the surface which is responsible for early paint failure.


Some window specialists say that boiled linseed oil is like frosting on the cake for the plants and bugs that eat the wood. Boiled linseed oil is the traditional material, but others like alkyd resins are less like food to the critters.

What do you think? Click "post reply" to comment.
John
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oculus
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Re: Wood Pre-Treatment before priming

Postby oculus » June 8th, 2011, 3:18 pm

Where did the 60/40 ratio come from? Pres. Brief #9 or some other source. I would like to see some documentation about using this formula on dry wood and the results from the application. I have never put it on dry wood myself. I used to put it on the glazing rebate until I read your forum, John which stated that it attracts fungus, bugs etc. So I switched to Penetrol.
I guess for me I would like to see some proof that it works. Pics or published paper.
Amy Harrington McAuley
Oculus Fine Carpentry, Inc.
http://oculuswindow.blogspot.com/
oculuswindow@gmail.com

"Opportunity is missed by most people because it is dressed in overalls and looks like work"-T.Edison

David Ottinger
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Re: Wood Pre-Treatment before priming

Postby David Ottinger » June 20th, 2011, 12:30 pm

Any thoughts of the relative merits of these 2 pretreatments for dry antique wood prior to primer/paint? The first from NBSS:

2qts raw or boiled linseed oil
2qts pure gum turpentine
1 pt spar varnish
Several teaspoons of Japan drier (a bit more if raw linseed is used)
1 pkg. of “Mildewcide”

and the second from Jeremy Ballard:
2 parts Val Oil
1 part Penetrol
1 part Gum Terpentine
1 part Spar Varnish-optional for uv protection but leaves more shine then I would prefer so I generally leave it out.

sschoberg
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Re: Wood Pre-Treatment before priming

Postby sschoberg » June 24th, 2011, 7:49 am

We're failry carefull here and unless the wood on a sash is really dry we do not pretreat. The thinking here is to allow the oil primer to penetrate fully. I don't want the primer to just sit on top of the wood. We use Cypress for our new wood storms and have run into this problem from the oils already in this type of wood. These oils were preventing the oils from the primer to penetrate. We overcame this problem by switching to a Zinzarr oil primer. We also wipe the oils from the surface of the new storms with Mineral spirits just prior to priming.


Steve S

johnleeke
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Re: Wood Pre-Treatment before priming

Postby johnleeke » December 16th, 2011, 8:55 pm

oculus wrote:Where did the 60/40 ratio come from? Pres. Brief #9 or some other source. I would like to see some documentation about using this formula on dry wood and the results from the application. I have never put it on dry wood myself. I used to put it on the glazing rebate until I read your forum, John which stated that it attracts fungus, bugs etc. So I switched to Penetrol.
I guess for me I would like to see some proof that it works. Pics or published paper.


This was submitted by David Gibney, one of the WPSC Founders, as part of his procedure that I used to create the outline for the Standards.

I've submitted it here to get an early start on a discussion of it.

So, I think that 60/40 mix comes from David's own experience. There is a very detailed study done 10 years ago on pre-treatments for window work. Here is a link to a discussion about it over at my own forum:

http://www.historichomeworks.com/forum/ ... php?t=2287
John
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http://www.HistoricHomeWorks.com

sschoberg
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Re: Wood Pre-Treatment before priming

Postby sschoberg » December 19th, 2011, 9:45 pm

John, one of the contributers on your homeworks forum link stated that for a pre treatment to work it must be toxic. This seems to be a key phrase. Will it hold up in discussion here? If this is true why not use one of the comercially available preservatives (Cabot and others) instead of BLO and paint thinner?

Would the use of Tuperintine be more in natural than BLO or a comercial mix? The smell of Turpentine is difficult to work with and difficult to mask.

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Re: Wood Pre-Treatment before priming

Postby johnleeke » December 20th, 2011, 11:44 am

sschoberg wrote:John, one of the contributers on your homeworks forum link stated that for a pre treatment to work it must be toxic. This seems to be a key phrase. Will it hold up in discussion here? If this is true why not use one of the comercially available preservatives (Cabot and others) instead of BLO and paint thinner?


Pre-treatments can work and be useful with out containing materials that are highly toxic, and in fact, I often make and use pre-treatments that don't contain highly toxic materials.

There are some different functions a pre-treatment can have:

-- consolidate a porous grey weathered wood surface
-- aid in the adhesion of primer
-- make the wood surface water repellant
-- make a surface with widely variable conditions more consistent for the next coating
-- help prevent damage from of mold, fungus or bugs

If your purpose is to prevent damage from mold, fungus or bugs then the pre-treatment can contain materials that are toxic to those organisms, such as terpentine. Usually these materials are called "preservatives." Pre-treatments don't have to contain toxic materials if you don't need specific treatment for mold, fungus or bugs at the surface of the wood. A pre-treatment that serves the other three functions can still be a good pre-treatment.

The smell of Turpentine is difficult to work with and difficult to mask.


Turpentine is pretty nasty stuff (which is why it smells so bad) and can act like a toxic poison in pre-treatments, primers and paints. The use of turpentine is one of the reasons why traditional paints worked so well. If you don't like the smell of it you can control the fumes with work practices like wearing respirators and using negative air pressure ventilation. There are other toxic materials that can be used in pre-treatments that don't smell so much, such as zinc-napthanate or copper-napthanate.

If you have a project where the use and smell of turpentine used onsite would be a problem, then you can use a pre-treatment that does not contain it. One of the reasons I make a lot of my pre-treatments is so that I can meet the specific needs of each situation and project and still get the maximum performance out of the pre-treatment. Sometimes I do use commercial products, but as I learn more about my work I have been making more of my own to get better results.

Would the use of Turpentine be more in natural than BLO or a commercial mix?


I'm not sure what you mean by "more natural."

...it must be toxic. This seems to be a key phrase. Will it hold up in discussion here?


Yes, these issues should be discussed here. We need to know what materials are toxic, and how they can best be used in window preservation work.

Now, who will write a standard on the use of pre-treatments?
John
Standards Co-Founder
Standards Editor

http://www.HistoricHomeWorks.com

sschoberg
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Re: Wood Pre-Treatment before priming

Postby sschoberg » December 21st, 2011, 8:12 am

I think the topic of pre treatment needs much more discussion and the standards need lots of detail and definitions both for each substance listed as well as a list of recommended recipes and what to expect, especially in production projects. Those say over 75 windows. Multiples window projects will bennifit from our standards. Our standards must not only have an objective to preserve and use but also be in tune in a production type atmosphere, where time is an important factor.
The subject of pre treatment has value but it needs to be explained what happens without it.

And will the standards allow the use of a comercial type pre treatment such as the Cabot product among others? I think if so than an explanation on how these work and what to expect should be written right along side of home made pre treatments.

johnleeke
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Re: Wood Pre-Treatment before priming

Postby johnleeke » December 21st, 2011, 11:26 am

Steve writes:
>>I think the topic of pre treatment needs much more discussion and the standards need lots of detail and definitions both for each substance listed as well as a list of recommended recipes and what to expect,...<<

I agree. Each of needs to post a message here describing what we use for pre-treatments that we know works, the materials and the step-by-step method, and the results.

>>The subject of pre treatment has value but it needs to be explained what happens without it. <<

I first started doing pre-treatments back in the 1980s to solve specific paint and wood problems, such as paint adhesion failure, and wood decay under the paint, that we later discovered were caused by the commercial paint products. By the late 1980s and early 1990s I had developed pre-treatments into a way to make up for the fact that the paint companies were changing their products too often to learn how to get long-term results with them, and also dropping the quality of the products. We began to push the service life of paint jobs (including window work) out to 15 to 25 years. We did this by using methods that were under our control (including pre-treatment), rather than depending on the products for success.

>>And will the standards allow the use of a commercial type pre-treatment such as the Cabot product among others?<<

Of course, the Standards include the use of commercial products. Here at the Forum we can name and talk about specific commercial products. In the final Standards specific products will not be named, but will be described with generic descriptions.

>> I think if so then an explanation on how these work and what to expect should be written right along side of home made pre treatments.<<

I agree, so if you are using a commercial product (or a site mixed treatment) please post a reply here on what you expect from it and how it works.
John
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Standards Editor

http://www.HistoricHomeWorks.com

johnleeke
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Re: Wood Pre-Treatment before priming

Postby johnleeke » December 21st, 2011, 12:11 pm

OK, here is my pre-treatment method. This is just one step in a five-step procedure for painting and glazing sash. This is not the only way to deal with pre-treatments. Please post yours.

Source: Save America's Windows, page 182, and Historic HomeWorks Forum, http://historichomeworks.com/forum/viewtopic.php?p=2466

This procedure assumes the double-hung sash are new and unprimed bare wood, or have had all paint and putty removed down to bare wood, and that all woodwork repairs have been done.

Do not apply any treatments, primer or paint to the side edges of the sash. Leave the edges bare wood, which leaves a surface where the wood of the sash can dry out, preventing peeling paint and keeping the wood free of fungal decay.

9a. Pre-Treat.

A pre-treatment may not be necessary if all the wood is perfectly sound (as with all new wood) and a very effective primer is used, but I find I can lengthen the service life of the paint coatings on old wood with this "fine tuning" of the coating system. Scientific studies at the Forest Products Laboratory have clearly demonstrated that a paintable water repellent preservative effectively adds to the protection of the wood and dramatically limits fungal decay extending the window's life.

In many cases the exposed surfaces of the sash are weathered and need a pre-treatment, while the glazing rabbet is perfectly sound wood and needs no treatment because it has been protected from the weather by the putty and glass. In fact, a pre-treatment in the rabbet may prevent good adhesion of the putty because the oil of the putty cannot seep slightly into the surface of the rabbet. This must be balanced with the fact that too much oil can seep out of the putty, leaving the putty weak right along the surface of the rabbet, leading to putty adhesion failure. The proper balance is found in the worker who can judge the character of the wood and the putty to create a successful and long-lasting seal between the wood and the glass.

One of the traditional practices is to always pre-treat the glazing rabbet with linseed oil, or a linseed oil and turpentine mixture. This still works, but some scientific studies have demonstrated that linseed oil acts like food for the mold and bugs that damage paint and wood. A recent practice to avoid this is to use other materials to seal the glazing rabbet, such as alkyd-resin oils and primers, that are less like food to the mold and bugs.

If needed, apply a penetrating pre-treatment to the bare wood. Apply the pre-treatment to both faces of the sash, all muntin bars and muntins, possibly including the glazing dadoes. The bottom edge of the lower sashes' bottom rail may need treatment if it shows signs of deterioration caused by water; if the bottom edge is in good condition it should not be treated since it has done well for so many years without treatment. Do not apply pre-treatment to the side edges of double hung sashes, and the top edge of the upper sash.

There are two types pre-treatment, 1. Paintable water-repellent preservative, 2. consolidating oil-resin. Paintable water-repellent is suitable for sound wood surfaces. (if waxy paraffin type (Forest Products Lab's WRP Recipe, Thompson's WaterSeal, or similar) apply to all surfaces of the sash, if sticky oil or resin type do not apply to sash edges (the surfaces that run in the jamb's sash tracks) and face margins (the narrow strip where the face of the sash rubs on the parting bead or the stops) Consolidating oil-resin treatment is suitable for gray weathered wood surfaces or surfaces that are somewhat "soft" or more porous than perfectly sound wood. The traditional recipe for this treatment is linseed oil and turpentine. I no longer use linseed oil because it is susceptible to mold and fungus attack. I now use a 50%-50% mix of mineral spirits and oil-based alkyd-resin varnish or a proprietary product (Flood's Penetrol, or similar) Just to confuse us all, there are some combination products that may be suitable. (California's Storm Stain Penetrating Wood Stabilizer, or similar) Water-based products of both types MAY be suitable, but all my experience and this recommendation is for oil-based products.

Penetrol is an oil-based product made of mineral spirits, linseed oil and alkyd resin that penetrates deeply into the wood surface. The mineral spirits evaporate leaving behind the oil and resin that cures and consolidates loose fibers at, and just beneath, the wood surface. Apply putty or paint primer when the pre-treatment is 80% cured. The amount of cure time is dependent on weather or shop conditions. Penetrol is like a light varnish or like an alkyd-resin oil-based paint without the pigment.

Storm Stain is a waterborne product that contains zinc napthanate and a very tiny amount of resins. Zinc napthanate is a preservative that limits mold, mildew and fungus. The resins help hold the zinc napthanate in the wood, but there is not enough resin to consolidate loose fibers at the surface of the wood. Storm Stain does not penetrate as deeply as oil-based pre-treatments because it is waterborne. After 24-48 hours the water has evaporated, the wood surface is dry, slightly tacky to the touch and ready for paint primer.
John
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Standards Editor

http://www.HistoricHomeWorks.com


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