Dip Stripping Windows: Don’t Do It!

By Scott Sidler October 7, 2013

Dip stripped windows
The right window is pre-dip stripping and the left window is after the dip tank

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.

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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!

 

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

  1. 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.

  2. 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. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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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