ONSITE ARCHITECTURAL PAINT STRIPPING
First appeared in PROFESSIONAL REFINISHING MAGAZINE, SEPTEMBER 1999
BY DEAN CAMENARES
So, you've landed an on-site restoration project, done all the appropriate planning, set up an operations center on-site and done the masking and basic site preparation. Now you're ready for the main event: stripping all the old paint and varnish from 100 plus year-old paneling in a room that will be a knockout when you're done.
In a typical project of this sort, you'd probably run into 15 to 20 layers of paint with an old coal of varnish buried below. Your job, of course, is to remove all that accumulated gunk so you can move onto the next step and refinish and restore the wood to its original beauty. But how to begin? If you've followed the previous installments of this series, you know basic principles of setting up your worksite, doing a proper and thorough job of masking and determining a course of action that makes sense to you. At this point, your most important decision has to do with what to use in removing all those layers of paint in a way that will not disrupt or destroy what you are trying to restore.
My recommendation is to start by using the N-methylpyrrolidone (NMP) class of wet chemical removers, which usually comes with a thick, paste-like consistency. Because NMP has a slow evaporation rate, it can "dwell" on the wood literally for days, slowly working its way down through layer after layer of paint and letting you pay attention to something else while it's doing its work.
That is an important point and can make a big difference to your bottom line. Indeed, in almost every on-site restoration project, labor will be your largest cost as you work inch by inch, foot by foot through a room or set of rooms and hallways. Doing what you can to keep those costs down is critical: if using an NMP remover, let the chemical do more work while freeing you and your crew to focus on other tasks.
Another factor in favor of NMP removers is that they are considered to be less toxic than most other removers, especially when you use them according to instructions and while wearing proper protective clothing. To be sure, no chemical strong enough to separate paint from wood can be considered harmless, but the NMP removers are less toxic than most of the chemical alternatives. (You might also want to explore the citrus-based removers or removers that use DMSO, a byproduct of paper manufacture.)
It's no exaggeration to say that NMP removers have changed the way restorers get the job done. In the old days (which weren't a that long ago), workers would have to stand by the woodwork, constantly reapplying remover to the wood surface, scraping it off, reapplying it, then scraping it off again, very labor intensive.
If you follow my advice and go with an NMP-type remover, you apply the material only once. When you're ready to scrape off the NMP-type remover, you'll probably go straight through to raw wood. And you can apply it to an entire section of the project, so that large areas will be in process at one time, which makes for quicker work. Just how much quicker and more systematic is something we'll look at next.
STEP BY STEP
When we're ready to apply remover to the woodwork we start by removing some remover from its bulk container to an easier-to-handle gallon or half-gallon bucket. We'll bring that bucket right up to the work surface and begin brushing or troweling or almost pouring it on. The object here is to get a quarter to half inch coating of remover over the entire wood surface, making certain we work it into all the crevices and dews. I like to start at the bottom and brush the chemical upward, allowing each stroke or pass to be a base for the next pass up the wall if you go top to bottom, I find that the material tends to -run or sag, which makes it harder to get a thick even build.
Even with all our masking, we cover the area directly below the application area with multiple sheets of newspaper. This way, if the chemical does run down the wall, we can easy collect it for reuse or, in later stages, for disposal. If these newspaper layers begin to get too soggy, we just lay new sheets over them and continue.
For brushing, we use chip brushes, 2 to 3-inches wide. For bigger jobs with suitable surfaces, we'll use 4 to 6-inch Verde plastic trowels, but I prefer brushes because they give me more control over application.
No matter how we get the material on the surface, we like to cover large areas entire doorways or windows, for example, or complete mantelpieces. Any area you cover will be left alone to let the remover do its work so the more you cover the better so long as you don't get too far ahead of yourself.
After applying the chemical to the desired thickness and making doubly sure that the nooks and crannies are adequately covered, we'll finish this stage of the process by covering the chemically coated woodwork with the paper supplied by the supplier of the remover or with a light, 5 mil plastic sheeting.
Next, using palms and fingers, we press and rub this protective covering down to flatten any air pockets and further evening the dispersal of the remover. The purpose of Us final covering is two fold:. It keeps the remover from drying out too quick and, perhaps even more important, it helps us ensure that the home's occupants or curious visitors won't accidentally rub up against the woodwork and catch an armload of goop.
Al this point, we back away and let the chemical do its job. In general, this means we won't even check on its progress until 24 or 48 hours have passed.
OFF IT COMES.
No matter what remover you've chosen to use, the next steps of the stripping process aim at getting rid of all the layers of paint and varnish and exposing the surface of the wood. Doing so requires the use of scrapers to manually lift the softened, wrinkled layers from the wood. In the case of NNP-type removers, this happens once you've peeled back the plastic from the softened coatings.
By far the best scrapers I've encountered for this work are pull scrapers designed to drag toward you. You have several options here, but I like the curvature of Sandvik scrapers and find they let me develop the most torque at the blade without biting into the wood. Of course, these are meant for use on flat surfaces.
As you draw the blade of your pull scraper toward you, you'll generally take off coatings all the way down to fairly clean wood, just what you want. I pull scrape all the areas I can, allowing the paint/varnish/remover residue to build up under the blade. When the gunk finally falls off the tool, it's no concern because the newspaper layers I've put on the floor will collect it for disposal later on.
Start at the top of the area you are stepping and always work down. This permits the recoating of a stripped area with paint or remover residue. As you go, always pull with the grain of the wood; otherwise, you can cause cross-grain scratching and tearing. Often, you'll be able to pull in long even strokes and move quickly. Naturally, you want to avoid drawing your blade over any details, carvings or crown mouldings: You don't want to plane away their design elements!
You also want to avoid a miscalculation many beginners make by trying to scrape the wood before the remover has done its work I've seen too many ambitious attempts at stripping wood turn into struggles because the operator grew inpatient and simply wanted to get on with the project. Don't make that mistake: Wait until the old paint is a buttery mess before you break out your blades. If for some reason the finish isn't ready to come off, it's best to reapply the remover and start over rather than make do with the botched effort.
For most woodwork pull scrapers will get the bulk of the finish off. At some point, however, it's likely you'll need to shift to push screwdrivers and perhaps picks, awls and dental tools to lift the finish out of crevices and finer detail. Again, these tools work best if the old finish is adequately softened.
I have two favorite scrapers: small, 1-mch putty knives and five-in-one tools the kind with a scraper on one side with angled and pointed edges. I generally like these tools to be on the dull side, because the sharp edges and points will likely gouge the wood.
Sometimes, the details and carvings need another coat of remover to completely soften the paint that has built up through the years. What you want here is to get close to 95% of finish removed from the wood with carvings and details picked relatively free of paint residue. At this point, there may be a haze of paint left.
So now you've gotten most of the old finish off. The wood is uncovered, the details have been cleared of almost all remnants of paint and you're ready to begin the next phase of the stripping operation by cleaning and washing the surface until nothing remains but the raw wood.
If you are accustomed to shop stripping that is, being able to power-wash a piece after scraping and scrubbing, you might get a bit frustrated with this part of an architectural restoration project. In fact, all of the hours you've put into scraping and picking the old finish so 95% of it is gone is maybe only half the time you're about to spend in getting the wood clean and ready for finishing.
You can't bring a power-washer into your clients' living room. What this means is you have to accomplish by hand over several days what a powerwasher does quite rapidly. Believe me, I've tried to find alternatives that would save time, but there's really no substitute for scrub brushes, synthetic scrubbing pads, plenty of rags and a ton of elbow grease.
The process now shifts from paste to liquid remover. Start by filling a clean quart bucket with stripper either a methylene-chloride based product, an NMP-type remover or another liquid remover. The important thing here is to select a non-flammable product: While acetone/toluene/methanol-type removers will do the job, it's not worth the risk of scrubbing a heavily waxed, flammable material over old woodwork that often has nails or other metal pieces at the surface and, of course, the occasional electrical outlet. Better to be safe am sorry.
Now apply a fresh coat of the liquid remover to the surface using a clean chip brush in an area of about 3 to 5 linear feet. Wait until the finish left on the wood has a chance to soften (this usually happens quickly) and begin scrubbing an area about a foot long with either a metal blade or polypropolene bristle brush.
Personally, I love using little "toothbrushes", with steel bristles at this stage, but select the brush that seems right for you. Basically, you don't want the brush itself to be too big or its bristles to be too stiff (these may scratch). What you're after is bristles that have enough flex to let you massage the wood and loosen any lingering paint residue.
Move through the section you've already wet and continue scnibbing (Figure 9). Once you've finished your scrubbing of one section, take a moment to wet the next one. TW way, the remover will be doing its work while you go back to mop up the previous section. You want to try to "lead" yourself through the process, step by step.
THE HOME STRETCH
When you return to the section you've finished scrubbing, you now need to wipe it down with a synthetic-abrasive pad (I use Scotch Brite) dipped in remover. I recommend than pads over steel wool because they rinse easily; in addition, if I'm using a flammable remover, I don't need to worry about metal to metal contact.
Next, take a T-shirt rag and wipe the area you've just worked. This should leave a fairly clean surface, perhaps with a little haze. Now apply some clean remover to this section, this time scrubbing it with brushes or pads that are wet with water. Just dip either one in a bucket of clean water and go at it, then wipe it again with a dry rag. lbs should leave you with a fully stripped surface. If it doesn't, simply repeat the last step until you get the results you need.
As you get one section clean, remember to lead yourself by wetting a new area so you can shift your focus to a new section where the remover has already done much of its work. If you're wondering why I use water at this stage, I do so because the removers I'm using are designed to be water-rinseable, which means they actually respond better to water than to lacquer thinner, paint thinner, naphtha, alcohol or turpentine all of which I've tried. Water gets the remover off faster dm any other solvent and better yet, there's no flammability issue to worry about.
If the water needs a boost to get the job done with a particularly stubborn sort of paint, I occasionally add vinegar, household bleach or a dishwashing or laundry detergent with bleach usually in a 5% to 10% solution.
What I'm trying to accomplish here is to get all of the stripper off along with any traces of the finish still left on the wood, and I've found that the water wash does the trick. If I have the sense that any residue has been left behind, occasionally I will wipe down the wood surface with lacquer thinner or alcohol after the water has dried.
I find that this extra rinsing step will sometimes pull more stain from the surface of the wood and even get at grime imbedded in the open pores of oak, ash or mahogany. It always amazes me to discover that what I had thought was fully stripped wood will give up a bit more of its original stains and pore fillers if I take the time for a final rubdown with a mixture of water and vinegar.
The process described here is intended to have you end up with wood that has been completely stripped of its finish and made ready for a new coating that will have every advantage you can give it for long use by your clients.
This doesn't mean the wood will look brand new. The woodwork in old houses ages to reveal a graceful patina, a character that bespeaks its history and the household objects that have bumped it, the children who've slammed into it, the common imperfections you have worked with but not eliminated. Your objective isn't blemish-free Surfaces; rather, what you're after is wood that looks as though it's been cared for and appreciated.
This expectation is a bit different from the expectations you'll find in dealing with your clients' furniture, a difference you should use it to your advantage. I'm not recommending that you leave all damage or discoloration as you find it; rather, I suggest making a distinction between damage that should be fixed and the marks of the wood's character and history.
If the wood is clear and clean, your stripping job is done and it's time to start thinking about the finishing process and restoring the wood to its full potential.
(Dean Camenares is a pioneer and technical authority on interior architectural wood stripping, refinishing and general restoration. He is the principal of East End Woodstrippers.)