this I am throwing out for anyone's comment:
Could anyone tell me why you can find sash that has survived 100 years in fairly good shape, seemingly without any regular painting, while the replacements for these sash using the best grade of pine available will only last 20 to 25 years max. On top of that these reproduced sash have regular painting and puttying rituals. I know for a fact sash that were produced in 1946 for a barn are still in place, made from just run of the mill pine, painted at that time and just once since--they are still in very good shape showing only minimal deterioration. These barn sash you can believe live in the harshest of environments a dairy barn with high humidity levels on the inside, and bare wood on the outside. this is one puzzle that has always evaded me and one that I think about from time to time, maybe some of you experts can enlighten me on why this is like it is-------------

Hewer

I don't know but I would suspect:

1. Fungicidal lead-mercury paint.

2. Fungicidal copper flashing and weather stripping.

3. Inferior joining of sash with a narrow crown staple pinning the mortise and tenon.

Thanks Roger for the reply:

Could you please expand out your answers somewhat to explain the connection in each of the 3 categories.

The sash construction was renewed using the exact configuration of the originals in all cases, even producing shaper knives to match the original sash. No new methods were incorporated for any of the connections.

The sash(es) were immediately primed, glazed and painted and put into service . The buildings that they are installed in are historic structures such as mills, houses, barns and shops. I would say that every building except the church has had new sash during the site's 41 year history since opening in 1961.

In the case of the sash used in the privately owned barn, the pine was cut on private property not graded to any extent, air dried for 1 year and then used to construct the new sash, which as I mentioned before are still in service after nearly 60 years, and going strong.

Please reply with additional information and thoughts, I certainly would like to know what is going on here.

thanks the NH

Hewer

My points 1 and 2 refer to older windows units and their anti-fungal properties and 3 to modern sash.

1. Lead based paint was in use in the US until the late 1970's. Lead paint was considered superior as a coating but was banned for toxicity. Paint quality suffered as new formulations were developed, present day paint is considered superior to the first generation lead-free paint. A common persistant and effective fungicidal paint additive was mercury also now banned.

2. Copper stripping was often used on the bottom of the lower sash meeting the sill, between the the upper's bottom and the lower's top and along the jamb and stop plus head flashing. As copper erodes a wash of fungicidal salts coats the building and millwork. Current windows use plastic gaskets, balances and stripping.

3. Wooden sash is now made with high precision glueless joinery often pinned in the corners with a staple. I view this technique as inferior, producing a less robust sash.

Sorry for the terseness. I was just writing about what I see and certainly not about your experience. I don't known the why's and how's of the sash failure you've seen but fungi are lurking.

Roger

Hi Roger;
Well I guess that I have learned something that I should have known, especially the lead paint which was definitely used and would have provided a large degree of fungus killing thereby extending the life of the sash(s) dramatically.
I do thank you very much for the extended explanation very well done,
The NH

I would suggest that the wood used in the surviving old window sash was probably heartwood, whereas the top grade clear sash wood available recently is primarily sapwood. That could explain the difference in durability.

Sounds like we need to change the name of this forum to "Chat With The Experts".

I agree 100% with the observations. I have one suggestion to help with the lack of availability of fungicidal paint today. The Preservation Resource Group offers numerous borate based products for treatment and pre-treatment that are very environmentally friendly. I would suggest treating the new sash with Bora-Care prior to painting. It also works outdoors on unpainted finishes since it is ethylene glycol based it isn't water soluable. Their less expensive product called Timbor works well for indoor treatment, but is water based. It might be okay for exterior use under paint, but for that you should ask th experts.

Their website is www.PRGinc.com