Back in November we shared or progress on our Window Restoration project, and then we got distracted by other projects.

This is the way of our home blogging and DIYing since the beginning. We start projects and then other projects take priority, so we stop projects. And sometimes we stop them for a long time. A really long time. And it makes Wendy angry with me. She doesn't understand why I stop them for so long, even though she does understand, but it doesn't mean she has to like it. 

Our entire lives as DIYers has been a series of overlapping projects and priorities. Some projects are really important, until another one is more important. In the case of our windows, I started them and then we started our dining room, and then we started stripping a bathroom closet door, and then I started cleaning the basement, and then we started our foursquare's dining room, and then I started working on some clocks. SO MANY PROJECTS! 

But before we get too derailed, let's circle back on that project that has been put off for so long that even once it's in progress, it gets put off again...the restoration of our original double hung windows. We left off in November by describing how we'd been able to successfully deglaze, strip, reinforce, and repair the first of five sash. 

The window that had been close to "toast," as they like to say on This Old House, had a new lease on life. That's the term they lovingly give to the things they could probably save and preserve, but it's not in the interest of their time or budget to try. Our "hobby" time is a large portion of our budget, so in our case, bringing it back from toast is what we love to do. After a good amount of work, the joints were once again solid, pegs reinforced and re-glued, and old growth lumber was used to patch in missing portions of the structure. 

But now that the sash was back to being respectable, what should be done to protect it and make sure it can last another 100 or more years (with proper maintenance)? The answer, a little thing I learned about on the Internets years ago called "Blopentine."

If you've noticed in the photos we've shared of the sash so far, the wood is somewhat to very weathered and grey. After the paint began the fail, the sun continued to bake the windows and the water from rain and snow penetrated all of the way to the wood. This left the wood dehydrated, and dehydrated wood is wood that's ready for rot and complete failure. 

The next step in our restoration is a relatively simple but extremely important one. The old growth, tight grain pine lumber used to build these sash is amazingly resilient. Much like many of our neglected DIY projects, they can bounce back from ages of disregard, resulting in something wonderful if given the proper attention and care. But the key to this ability to properly bounce back and provide years more functional satisfaction is to properly hydrate and protect the wood against its most natural enemy, water. The best way to accomplish this is to hydrate and seal with wood with something that repels water...which is, naturally, oil.

BLO-Pentine, a word which I will use incessantly, is a made up concatenation of an acronym and partial word that I first heard from a window restoration specialist, "Jade," on the Old House Web restoration forums probably a dozen or so years ago. The word represents a 50/50 mixture of Boiled Linseed Oil (or BLO) and Turpentine. At some point it was even shortened to BLOP, I guess because of Boiled Linseed Oil + turPentine?

The idea here is simple. The boiled linseed oil, which is a favorite of woodworkers and restorationists for its protective power (and somewhat pleasant acquired smell) when it comes to protecting unfinished wood. But when dealing with dry wood, applying the linseed oil alone will often leave the oil simply sitting on the surface of the wood, never actually penetrating into the thirsty wood fibers. 

By combing the linseed oil with the turpentine as a 50/50 mixture causes the turpentine to act as a delivery mechanism for the oil into the wood fibers. The thirsty wood will essentially drink in the mixture, rehydrating the weathered wood. Then, as the turpentine begins to evaporate as the mixture dries, it leaves behind the linseed oil, both on the surface and impregnated in the wood. The linseed oil then slowly cures, leaving behind quenched wood that now has natural protection against the elements. 

Sounds easy enough, right? But it's very important to use extremely high quality products with this process. The turpentine you're probably most familiar with is a dirty, cloudy, and awful smelling product. If you're looking to create yourself some Blopentine, it's best to source yourself some linseed oil and turpentine that's essentially top of the line. 

We bought our linseed oil and turpentine from American Rope & Tar. (, what an amazing domain name.) Both are imported from Sweden and the turpentine is crystal clear and actually has a scent that I find pretty pleasant (but Wendy dislikes). It truly smells like it's straight from the tree.  

When I mix up my Blopentine I like to mix a little at a time. I prefer the use of clear plastic cups to eyeball the amount, and then mix it by stirring and gentle shake/swirling in a mason jar. That way if I don't use it all, I can set aside what's left for later use as it does have some decent shelf life when stored. 

You can apply the Blopentine in many ways, but I like using a foam brush. This lets me load the brush up with a good amount of liquid, then I can apply liberally.

When the mixture is applied to thirsty and weathered wood, you will see it quickly absorbing the Blopentine and just drinking it in almost as quickly as you can apply it.

In our case I ended up doing three coats of Blopentine, allowing it to dry thoroughly between coats. My first coat was heavy and I kept applying more while I could see the wood easily slurping it up. But once I noticed it was sitting on the surface more than being absorbed, I gave it a break to begin drying. This meant leaving the sash to dry for a good 12 hours between coats. 

I left the sash slightly elevated and put a fan on it to keep the air moving around the sash. I know it's oil, and it will cure on its own time, but keeping the air moving will help the process just enough.

Once the mixture was fully cured, which can take a week or so, by hand I lightly went over the whole sash with a 400 grit piece of sandpaper.

At this point our sash was fully hydrated and ready for our next steps in restoration. We'll share more about the next steps in the coming weeks, but I really wanted to dedicate a whole post to Blopentine, the boiled linseed oil and turpentine mixture. It's such a critical and important part of this whole weathered wood restoration process and it what I hope will result in a wonderful end product once the windows are done. 

Are you sick of reading "Blopentine" yet? Have you ever used boiled linseed oil to restore or finish antique wood? And do you have strong feelings about turpentine, its smell, or the quality of turpentine that you've used? It's not too likely I guess, because I tend to be sort of a nut about things like this. I hope this post is informative and useful for you in your window (or general wood) restoration endeavors.

Comments 7


3/2/2018 at 5:24 PM

Yes, my husband uses BLO and mineral spirits because the mineral spirits doesn't smell and acts as a dryer. He mixes 1/3 mineral spirits, 1/3 boiled linseed oil and 1/3 spar varnish, which he applies to raw wood. He wets the wood first to raise the grain, allows it to dry overnight, then next day sands it with 320 paper, whip all the dust off then applies the 1/3-1/3-1/3 mixture. He uses this on the finish of the Windsor chairs he builds. He applies this mixture over the milk paint, only allowing it to soak in for about 15 minutes. He applies about three coats to get the look he wants, then applies wax for the final coat.


What a great finish that must be. Sure beats the pants off most modern finishes. If I do any custom pieces in natural finish, especially on reclaimed antique lumber, I'll almost certainly use a similar recipe. Thanks for sharing!

3/2/2018 at 9:17 PM

I really appreciate the education I get from your posts, whether or not I ever get the chance to use the information. I think I just like the fact that people like you go to the trouble to research the best ways to restore and preserve things that have history, and may otherwise be consigned to the scrap heap or a bonfire.


I love this comment! This is exactly why we started this blog and also why we always want to keep posting. If our efforts can help help someone learn or figure out something that might work for them or someone they know, we've accomplished our goal!

9/30/2020 at 10:17 AM

Thanks for the helpful info on making sure those old windows last even longer!

Kimberly Beasley
6/13/2021 at 3:45 PM

I’m wondering if you would do this step prior to using epoxy repair to fill holes/missing chunks or after. I feel the blopentine wouldn’t do much good with large chunks of epoxy, but I also want to make sure I don’t ruin the adhesion of the epoxy to the wood..


I’ve done both with good results but I think it’s better to do the blopentine first then epoxy. It’s similar in many ways to the hardener/consolidator from Abatron.

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