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Dip Stripping Windows: Don’t Do It!

Dip Stripping Windows: Don't Do It!One of my first large scale window restoration jobs was to fully restore all 38 sashes on a 1950s Colonial Revival. I had restored close to 100 old windows by the time this job came around and had gotten pretty good. My glazing putty had nice clean corners and I had developed a pretty good process with my small team.

This job was a big one for us and it had a time crunch to boot. The thick layers of factory applied 1950s alkyd paint on the windows was so tough that it laughed at my infrared paint remover. Steam seemed to have no effect either. The first batch were dry scraped, which took FOREVER. I had to find a way to get the paint and putty out and still make a few dollars to pay my team.

I had heard of dip stripping and knew it wasn’t the best option, but I was out of ideas. I brought the next batch of sashes to a local dip tank operator who gave me back the sashes in a couple days without a trace of paint or putty. Brilliant! So, I decided to bring the remaining sashes to get dip stripped before we finished the restoration process at the shop.

The windows came out beautifully. I was proud of the results and the client was very happy as well. Three 3 months later, I got a troubling phone call though. The paint had begun bubbling up on the windows, particularly on the joints, and a brown ooze was leaking out. I had never had a problem like this before and had no idea how to deal with it.

I was on the phone immediately with window experts around the country trying to figure out what was happening and how I could fix it. I came to find out that what my windows were suffering from was the notorious “brown-ooze.”

The Brown-Ooze

Brown Ooze
The “brown-ooze” at work

The “brown-ooze” is a terrible, terrible side effect of dip stripping windows and doors. It doesn’t happen every time, but when it does it is kind of like cancer. No one knows how to stop it…yet. I’m confident there is a way, but so far the world is still looking for a cure.

What happens is this:

    • Since the window is submerged in the solution for hours or days the alkaline liquid used in dip stripping penetrates the joints in the window and soaks deep into crevices
    • After being removed from the dip tank the windows are hosed off and a neutralizer like oxalic acid is applied to the windows to neutralize the stripper
    • The windows are once again rinsed and then left to dry. While drying the remaining stripping liquid that is trapped in the joints crystalizes and lays in wait
    • The windows are primed, painted and reinstalled

Once reinstalled the windows are subject to rain and weather again where the moisture content of the wood raises and falls with the environment

  • As the moisture level raises high enough the crystalized stripper re-emulsifies and begins to strip off the paint from underneath, causing brown liquid to ooze out small gaps in the paint
  • The gaps created in the paint allow more water into the window joints and the process grows like a snowball rolling down a mountain

The Aftermath

Luckily, I have some of the greatest clients in the world. My client has been patiently letting us experiment on their windows to try and find a cure for this awful diagnosis. Some of our work has been promising and I’ll share those findings as soon as I know they have staying power. Other attempts looked like we had cured it only to have it come back even worse.

It is a tricky issue and one that needs the help of anyone who has ever come across it. I’m hoping to crowdsource a solution by publishing this post since most window restoration experts I’ve spoken to are also at a loss as to how to salvage windows suffering from a bad case of dip stripping.

There is a discussion on the topic at Historic HomeWorks if you’d like to read more.

Next week I’ll walk you through the proper way to restore windows from start to finish so you can be sure to avoid this scenario. Till then, fight the good fight!

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34 thoughts on “Dip Stripping Windows: Don’t Do It!

  1. Hi Scott & everyone
    We have a Queenslander & had our windows dip stripped some 6 years ago with the negative results of brown stain leaching & paint blistering.
    We are about to embark on trying to reverse the affects of the dipping & repainting.
    We are planning to try vinegar soak & then an oil based primer, then repaint
    Just wandering if others have still found this method to be the most effective in revearsing/stopping the affect of the chemicals used in the stripping process
    Thanks Betnie

  2. Really interesting article, I found my way here because I was considering alternatives to stripping other than sand blasting for speed. I think you will solve the problem to an extent by using an oil based undercoat next time, and sealing the glass to the putty with an oil based gloss internally/externally. Where the bubbling starts suggests the moisture has come in from the putty externally into the timber joint in the corner of the glazing bar, seeped in, then activated, or internally (condensation ran down the glass, into the joint, and down the mortice and tenon of the glazing bar.

    I’m pretty confident that compound would have remained dormant if no moisture could reach it, so go with oil based next time, that said, I don’t think I can take the risk just in case clients do not keep up maintenance over time, so I’ll stick to sand blasting, however slow the process is.

    If you did use oil based paint, then I can’t see a clear solution other than next time, you can disassemble the sash, clean the joints, and cramp it back up. that would be a sure cure but extra work though still much less than manually stripping the sash!

  3. Hi Scott,
    I’m a great fan of caustic dip stripping casement windows (among other items). We restored the external windows (cedar frames, linseed oil putty and arctic glass) and original kitchen cabinetry (dipping the doors) of our 1950 built home in Central Queensland (Australia) about 12 months ago with no ill effects to the new painted surface (we used quality oil based gloss enamel and primer).

    I’ve used the process previously on furniture. The first trick to it is heating the solution before putting the timber in and second, not leaving it in for too long.

    I left our windows in for 30 minutes max and did abit of mechanical removal as well (stainless steel and nylon scourers help break up the layers) given the windows had been painted many times in their life.

    Not all the paint was removed and you still get timber fibres standing up but the sanding job is way easier.


    1. I guessing the problem is acrylic breathes and allows moisture penetration, whereas because you used an oil based system externally rain and dew can’t penetrate the timber, I’m thinking if your dipping windows then completely encapsulate the entire window top bottom sides as well as glazing/putty beds in an oil based primer to insure absolutely no water penetration, remembering that condensation buildup on a plane of glass will make its way down to the putty bed and that’s where it will penetrate most

  4. I have dipped and stripped furniture for years as well as woodwork left on my stairs (decorative Newell post and side piece) with no negative results. Especially those mentioned in previous posts. After dipping or stripping I always clean up the wood with denatured alcohol. It gets any residue paint or stripping material out of the wood before applying any final finish.

  5. Doors are great for stripping if you don’t repaint. I am stripping my 138 year old doors and then recovering the natural wood in linseed oil coats. Best way to do it to preserve the detail iin the wood that gets messed up by using even small scrapers that are designed for iintricate details. The labor would far exceed the cost and the clean up for lead paint is messy. If you do use a stripper and tools, there is a great scraper tool with six blades and 12 different sizes and shapes that works awesome. I used it for molding and it works really well. Got them at Home Depot. $13.

    1. Doors came out great. Had to drive 100 miles to a stripping business and paid them $220 per door, too much but out of town and nowhere else to go and cheaper than hand stripping due to high labor costs in my area. They also sanded the doors. We went over them again and then put a coat of linseed oil on them and they sucked it up nicely. Came out beautifully. May not even apply a second coat. Awesome transformation and much cheaper tha buying equivalent new doors and installing them.

  6. Hi,
    I had the same problem with brown goo exuding from the wood after I got some pine doors dipped. Most areas of the doors were unaffected but some parts seemed never to dry and were darker, with occasional weeping of brown goo. As I understand it, its probably a soap like substance caused be a reaction between the caustic and oils in the paint, which seeps into the wood. Anyhow a potential solution which I have been experimenting with (and quite excited by) is Calcium Bentonite Clay or Fuller’s Earth. Its a type of clay, which comes in powdered form. I mixed it into a paste with water and a little vinegar and painted/trowelled it on over the affected areas. It may work better to wet the area first… It appears to draw out the residue from within the wood and is trapped in the clay, which can then be scraped off and washed away with water…several applications were necessary but it seems to work very well to get rid of the problem.
    Hope this helps someone.

    1. I think you’ll find it’s the acetic acid in the vinegar that is neutralizing any Caustic soda left in joints and cracks

  7. I have been restoring windows and doors in the NW region of D.C. for about ten years and anytime I have something dipped in acid, I pray that it falls apart, because if it doesn’t, I take apart all the joints and rebuild the item. It is the only way I know how to ensure that you will never get any ooze syndrome. However, I wonder if applying a nice coating of elastomeric epoxy inn and around the joint would keep the ooze inn.

  8. I’ve been dip stripping for years and the way to get the the residue out is to wash am really good like two or three times and then use regular vinegar and soak them with vinegar and that will take that goop if it’s if it’s been leaking Google take the goo off and it will get it ready for paint will neutralize the caustic soda

  9. I do have to say that I had some cabinet doors dipped. They were solid slab maple, with no glue. The process worked beautifully. With sanding and polycrylic, they came out spectacular.

  10. I want to strip layers of paint from a 40’s era home. I only want to do the baseboards. Seems to me acid dipping would be a safer and more efficient way of going about the project.

    Problem I have is there are no “DIPPERS” in my town. What chemicals are used so I can make my own?

    Or can you confirm if dip operators are the same guys who do vehicles ?

    I won’t have the same problem as you had since there is no glue or joints to deal with, which is what seems to be the problem. Hand stripping these lovelies would be a nightmare since they are rather ornate.

    1. Liv, chemical stripping in place may be easier than removing everything, dipping and then reinstalling. I’d probably try an infrared heater to make paint removal easy or check out my post about chemical strippers for my info.

    2. Scott mentioned infrared paint removing. The low infrared heat from a Speedheater will soften the paint easily. Eco-Strip is US distributor.Your concern about the ornate wood could be solved by having a pull scraper with small curved edges. A special scraper called Boomerang Scraper has a 1/2 ” curve at the bottom & 1/8 ” rounded tips. Works well on narrow grooves and detailed carvings.

    3. My bedroom was a huge success & and a safe one.
      Used “Back to Nature Lead Off ” paint stripper.
      Follow directions. Took 72 hours but came off easily. MUST wash down roughly with warm water.
      Time consuming-took 12 full days but hey “Old houses are a Labor of Love”

  11. The 2 coats of shellac seems to be doing the trick! It’s been 2 months + and I got a surprise text from my customer. She said, “I still can’t get over how gorgeous the cabinets came out!”

    What a relief to hear that!!!

    Hope this helps.

    1. Hi Scott,
      This has been a helpful article. I was a bit confused with your cabinets…did you use the shellac underneath the paint as a primer? Or were these cabinets a straight shellac finish that you were looking to maintain? Wasn’t sure where the shellac came into play.

      1. Hi Jon. The clear shellac was used over finished urethaned cabinets that were still seeping some wierd white haze from a previous dip stripping. Then I finished the cabinets with a waterbased urethane.

        1. Thanks for the info Mark. I wonder if shellac or something similar could be used as a sealant at joints experiencing this issue prior to painting. Sounds like the shellac works to contain the ooze and hazy texture from spreading? Wondering if this could be applied under a paint layer in other cases to ensure that the reacting lye doesn’t seep out through the joints…

          1. I would certainly think it would be worth a try. The shellac not only stopped the chemical haze that occured it also made it disappear just by applying it. Wish I had tried shellac 1st before I tried an oil based sanding sealer and an oil based urethane. Let me know how it goes!

    1. Finger crossed, but I believe we have. We scrapped the paint and primer down to almost bare wood and put fans on the sash until the moisture content was down to a reasonable level 10-14% instead of the crazy 30-50% it was at. We ten primed and repainted leaving the sides bare so the sashes could dry out by themselves if needed. Seems to be working for now, but that’s only 8 months of field testing.

      1. Thanks Scott. Had some cabinet doors dipped. Some chemical reaction caused the polyurethane to dull and have a white glaze. Had them machine sanded back to bare. Let them dry a few months. Restained, polyed and seeing some slight glazing again. Will try to sand to bare the bottom or too of the doors and will try to seal with shellac a couple of coats.

      2. Hello Scott,
        For what its worth, I tinker with biological formulations to clean-up water and soil polluted with industrial waste. I’m thinking that if the windows were immersed in such a solution for a period of time, live bacteria culture would eat away at a lot of the hidden residue that re-emerges as “brown ooze”. I am working on my own house, and never considered a complete reconditioning of the old sash windows, but this may give me reason to experiment. Will keep you posted. Best regards, Steve W

  12. I had an antique rocking chair done years ago… NEVER again!
    Totally destroyed the chair and joints.
    Lesson learned.
    Hand stripping with sandpaper is my way to go.

  13. Dipping also causes the glue joint to break down. This is common when one dip strips wooden shutters and it is awful. It’s just a matter of time with them before the louvers start “racking” and slipping like dominoes.

    A similar leaching of chemical strippers applied to painted surfaces manually can happen, even if they are neutralized and washed. The remaining crystals cause the paint to fail, too. Try SOYGEL. Then there is the issue of assuring the wood is completely dry before glaze and repaint. If not, the remaining moisture may cause the paint to pop off/fail, too.

  14. Sorry to hear about the dipping problem. In old car restoration people have the same problem. Dipping a car in acid to strip the paint, car gets repainted, then months and years later brown ooze starts leaking out of the joints and ruining the paint job. I haven’t heard of any solutions.

    The preferred stripping method is media blasting, walnut blasting, or sandblasting. But that’s on a metal car body. Not sure how’d it go on a wood surface.

  15. Several folks have recommended this same process for doors……….. I’ve been reluctant ” too good to be true” and have read some concerns regarding dissolving the glues in the door as well…………after this article…. NO WAY

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