Wood is corrosive by nature, as it contains acetic acid (C2H4O2). The low spots retain the gloss/satin of the poly. (That's why testing is critical for a nice finish.) The more edges a job has, the longer and harder it will be to sand. In addition to blotchiness, the softer areas between the grain lines soak up stain like a sponge, creating an unnatural look. If you are not familiar with wood sanding or refinishing, ask questions at a home improvement store about the right sandpaper grit to use for your situation. He has many years of installation, sanding, finishing, gymnasium design and technical consulting experience, which he uses to assist his flooring customers on a regular basis. Corrosion from a different iron (III) oxide, magnetite (Fe3O4), however, produces a black-colored rust. The popularity of using wood as flooring has ebbed and flowed throughout recorded human history. From straight-lay strip to parquet, herringbone and more, these articles offer the 411 on wood floor installation. My sanding is complete and floors look good now, but is there the chance that the same will happen? To confirm that metal particles could cause such black spots, I needed to research the effects of combined wood, chemicals, and metal. We needed to put them together and reproduce the black spots. creates rust. It sort of looked like a little piece of flattened plastic about 3 or 4mm in diameter. Some types of wood, like pine, cherry, birch and maple, are notoriously difficult to stain. The spots are getting bigger and more are appearing each day. Removing these stains involves sanding, bleaching, re-staining to match the existing stain and applying a clear coat. Once sanding is complete, wipe all dirt from the surface and make it clean. Once we recreated this process, all four waterborne finishes rapidly created black rust spots. Unlike paint, which just sits on top of the wood and can be sanded off, wood stain penetrates into the fibers of the wood like a sponge absorbing water. I am refinishing my floors and I don't want the same thing to happen. A Wood Flooring Timeline: Ancient Times to Today, Q&A: Removing Stain and Finish Spills on Concrete, Trick of the Trade: Is That Stain Really Dry? Now You Know. Sanded wood should be mostly â¦ In the photo you can see where a bolt, a bracket and even a nail have been left on the deck and they have left a faint stain behind. This might support the claim that the black spots were multiplying. Most said they had recoated the floor with spots and moved on, with mixed results. Black stains on hardwood floors can ruin the appearance of an otherwise beautiful hardwood floor. The spots are formed when the wood is exposed to metal and moisture, e.g. However, black mold on wood often leaves lasting black streaks deep within the grain, even after the mold spores have been killed. By Renee Miller Updated December 10, 2018 Dark stains on wood flooring are usually caused by urine or water spots that have remained untreated. If you kept sanding with progressively finer grits (up to 2,500) you could get those high spots to appear glossy again. Any scratches will be enhanced by stain. Determining when the stain is ... Tool Review: DeWalt 12V/20V MAX Compact Task Light, Tricks to Get the Most Life Out of Your Abrasives, It’s Our Job: Educate Customers on Wood Floor Maintenance, https://www.nortonabrasives.com/en-us/markets/floor-sanding?utm_source=Wood%20Floor%20Business. Such chemicals can create lower oxygen levels, which also tend to create black rust. Step 2. As I searched for more information on this problem, all I could find were vague references to metal shavings—common on hardwood floor projects due to contractors sharpening scrapers over the floor-causing black spots with waterborne finish, but nothing explained when, how or why this occurred. Kirk Dozek, owner at Kirk Dozek Wood Floors in St. Clair Shores, Mich., tried this new light. For one thing, it'll take a long time to finish the project. The complaint included the presence of random yellow streaks of old finish and the black spots. Following is what I learned. After sanding, wipe all surfaces with mineral spirits and inspect for scratches or sander swirls. Once the wood has been sanded, it should have an even surface with non-jagged or rough edges, it will take on a lighter color appearance, and often the grains of the wood will show more. Unsightly black stains on a deck are caused by metal being left on a wet deck. A board that has a nice, attractive grain pattern can end up with dark, splotchy areas after you apply the stain. This room is on a second floor, so no water problem. Species high in pH have higher corrosion levels. If metal shavings were the issue on the floor I saw, my "educated" guess would be that the waterborne finish was corroding the particles; I had never seen this with oil-modified finishes. It usually occurs when you are attempting to sand out discoloration, a spot, defect, gouge or a scratch. You have to wait for each layer of stain to completely dry before adding the next. It reacts with the tannin in the wood and turns black. Complete DIY projects like a pro! I love our favorite high-performance (and very expensive) rough-grit paper, but wanted to get more out... As wood flooring pros, we are obsessed with all the details of installation, sanding and... Everything from basics on running the big machine to detailed buffer techniques and more are in these wood floor sanding articles. Mineral streaks/deposits are a discolored line, spot, or band in the wood that may range in color from light gray to tan, olive green, brown, purple, blue, or black. Let it dry and add a second layer of stain to all but one section. 2. A pencil line can only ride over the top surface not getting into the low spots. Common red-colored rust comes from hematite (a mineral form of iron (III) oxide, Fe2O3). The use of the best hardwood steam mops is recommended for sealed floors. I am thoroughly pleased with our testing and hope this black spot mystery is solved. In addition to blotchiness, the softer areas between the grain lines soak up stain like a sponge, creating an unnatural look. The homeowner told me the black spots appeared soon after the floor was resanded and had become increasingly worse. Otherwise, youâll cause damage to the wood and wonât be able to properly remove all the wood stain or even worse, get the stain even deeper in the wood. I did a ton of research on how to remove urine stains from wood and floors. To remove the black stain on your floor, you can use hydrogen peroxide, vinegar, or baking soda. Let's find out. After the stains are completely dry, fix a 180-220 grit sandpaper into an orbital sander. If aesthetic is important, you can attempt to sand the black streaks out, but you may have to remove several layers. Sign up for our newsletter! Measure the rooms and get the actual square footage. It is rare but it does happen. A: I can only makeâ¦ Black spots on wood floor even after sanding. We recently bought a house built in the 1920's. b) Sand the wood: Before you apply the black tea water as a wood stain, prepare the wood piece by sanding it. In fact, some stains will dissolve the stain below even if it is dry. It looks like it may have been sprayed with some sort of pigment or dye in some spots, mainly on one side.. c) Stain the wood: Apply the black tea onto the wood surface using a paintbrush. These spots require the surface to be sanded and refinished in order to totally remove them. The test board shows the effects of different amounts of wood stain sealer. Most people recommended hydrogen peroxide and according to them had great results. Worldwide leader. How big is your job? Robert Higgins, an Ormond Beach, Fla.-based independent consultant, answers: Oak wood naturally contains a very high amount of tannic acid. If the mold stains still remain, the wood surface will need to be sanded to remove the spores that have deeply penetrated the wood. Even potty trained pets have accidents. Stephen Diggins works for Wood Pro Inc. in their Salem, N.H., branch as manager and training director. The chemical compounds found in waterborne flooring finishes can speed up the corrosion process more than just water. Spots! However, items such as oil, water, grease and pet urine will create black spots on the hardwood floors. I am using an orbital sander with 180 grit sandpaper, but after only about 30 seconds, it stops working quite so well. We had acidic wood, metal particles susceptible to black corrosion, and corrosive chemicals. Any blotch-prevention program starts with evenly sanding to 180 grit on face grain, and to 220 grit on end grain. Black stains indicate that there is a heavy build-up of dried uric salt crystals. You'll be amazed at the results. Whether it is used for house siding, outdoor furniture, decks, fences, or sheds, wood holds up well against weathering, as long as it is maintained.But whenever water and wood mix, there is the possibility of water stains. Kiln drying accelerates the production of free acetic acid, making wood more immediately corrosive than when air dried. Prepare the wood surface as you normally would by sanding to 180 or 220 grit; Prepare the dye by diluting it by 50% with water in a mixing container. Apply the final clear finish to see how it looks. Black spots did form, however, on a piece of red oak that was not part of the testing. :( You can remove the black spots and restore the look of your hardwood floors, but it takes more than an everyday cleaning regimen. Common red-colored rust comes from hematite (a mineral form of iron (III) oxide, Fe2O3). If by hand, use a big sponge so you can work fast and cover a lot of area. The streaks were in locations where it was likely a metal file had been used. Sanding will also help open up the pores of the wood so that they can absorb stain better. Repeat this process until you get to the desired color depth. Be careful not to start sanding before the previous wood stain dries. The difference appeared to be whether the metal shavings were worked into the open grain of freshly sanded wood. Linseed can turn the oak and some other wood types, black. Mineral streaks/deposits are naturally occurring, and they are often considered to add value and visual appeal to the wood. Corrosion from a different iron (III) oxide, magnetite (Fe3O4), however, produces a black-colored rust. Firstly, sand away the top layers of the worktop to remove the finish, then continue to sand until the black stain has been removed. However, a trace coat is the best way to identify high/low spots in wood for sanding (using a very weak dye solution to coat the entire wood surface). The basic organic components of wood fiber are cellulose, hemicellulose and lignin, but wood may also contain volatile alcohols, esters and oils that, when combined with metal and corrosive chemicals (such as floor finish), can create an environment even more susceptible to corrosion. A dark brown, or black mark indicates water has reached the wood itself so a quick fix isn't possible. Our latest shed is also a pavilionâand you can build it, too! After the test board dries, examine the results in different light and locations to see which amount of stain gives the most appealing results. Block Sanding. Keep in mind that 500 square feet in a big living room is easier to sand than 500 square feet in three bedrooms, three closets and a hall. If you sand the wood now, you will remove the stain on the wood, which is a bad thing, its called a sand through. Black spots are usually caused by water that has been left to sit on the surface and has penetrated the finish completely. Sanding. Apply the dye. Everything from basics on running the big machine to detailed buffer techniques and more are in these wood floor sanding articles. Otherwise, the new coat will dissolve the previous coat and you'll have a real mess on your hands. What Causes Mysterious Black Spots in Wood Floors? Another problem with multiple coats is that the stain will begin to obscure the natural grain. I then noticed that there were black spots on the sandpaper. Chemicals present in the floor coating process (water, formic and acetic acids, and others) can stimulate electrochemical cell activity, which also accelerates the rate of corrosion between metal and wood. Itâs not advised to try to sand the dark spot away, as doing so will almost certainly leave a depression in the wood. With almost 30 years in the flooring industry, he has been a freelance columnist for magazine, newsprint and online medias and has conducted product seminars ranging from wood flooring to luxury vinyl tile. Once you've chosen a sealant strength, apply it to the end grain before you stain. These discolorations will cause your hardwood floors to look old and dingy. Wood fibers will conduct the flow of electrons much like wire; this electrical flow causes metals to break down and rust, thus explaining the importance of the metal actually coming into contact with raw wood fibers. You'll get a bit more blotchy appearance, but the grain will show up betterâa fair compromise. Prepare a new test board with your chosen sealer concentration. The safest approach is to first ... Tim Nathan, market specialist/upper Midwest regional manager at Basic Coatings, shared this tip: Make sure you sand the wood well before applying stain. Innovative wood floor sanding technology. The flooring contractor told me he had used a metal file and a 1-inch wood scraper (high-carbon steel) when attempting to remove the old yellow finish streaks that hadn't come out with sanding. Normal living conditions were established: 68 degrees F at 32% relative humidity (RH). Decide which amount of wood stain sealer gives you the desired look. Industry Leader in the Professional Floor Sanding Market. Oak has some of the highest pH levels and is one of the most acidic and metal-corrosive wood species. You can scrub with Barrettine Cellulose Thinner and this will help to remove some of the staining, but any stubborn stains may require sanding back to remove. So, how should wood look after sanding? If you are sanding critical flat surfaces by hand, you should always use a flat block to back the sandpaper. Sanding removes the scratches and dings, but not the ugly dark color. I recently came across a condition on a hardwood floor I had not seen in my 25-plus years as a consultant: a red oak floor littered with tiny black and gray spots. Wood flooring abounds in modern building construction—from apartments to homes to workplaces. We recommend our users to update the browser. Since displaying our results in our showroom for local contractors, we have had a few "witnesses" recall black spot issues. But there’s a simple way you can prevent most stain blotches. BUT.. after sanding my floors, and spraying them with peroxide, repeatedly, the stains were the same. Basic Wood Floor Installation Basic Wood Floor Installation. A 500 square foot job is about as about as big as a first-time do-it-yourselfer, working alone, can possibly expect to sand in one weekend. Upon testing, metal filings from the same brand of scraper blade were added to four wood floor finishes and applied to red oak. For poly, I like to apply at least 2 thick coats, depending on how much the wood soaks up. Those who chose to recoat with oil-modified finishes said they had no further issues. Three things are needed to make ferric oxide (rust): iron, water (moisture) and oxygen. If you use a random-orbit sander, follow up by hand-sanding with the grain using the same final grit. Donât create a gouge in the floor but use long stokes, going in the same direction as the grain of the wood to remove things like these random black spots we had all over the floor. Dark stains. Manufacturing the Finest Hardwood Products Since 1947. How can you remove these stains from your flooring, and which is the best way to go? How can I remove the stain? We are no longer supporting IE (Internet Explorer), How to Stain Unfinished Wood with Used Coffee Grounds, How to Match Wood Stain: Head to the Paint Store, Do Not Sell My Personal Information â CA Residents. The wood itself was physically and chemically crucial to the corrosion process. For the hardwood flooring industry, "Black Spots" seems to be the appropriate common name moving forward. From straight-lay strip to parquet, herringbone and more, these articles offer the 411 on wood floor installation. It wasn't always like that. There's even a few before and after videos on YouTube showing results. Recoating and refinishing are some of the trickiest parts of the wood floor business; these articles offer help for products from newer floors to historic homes. The photo below shows the dramatic difference between the raw and â¦ #5 â After youâve gone over the whole floor once with the course grit sand paper use a hand sander over spots that need extra attention. For a more technical discussion, perhaps "MPCC" (Metallic Particle Corrosion Contamination) is appropriate? You can use a medium grit sander to sand the wood. Some waterborne floor finish had been accidentally spilled on a scrap piece of oak where the scraper had been sharpened, and these spots were exactly as seen in the claim floor! Focusing your efforts on one spot creates an unwanted divot or dip in the wood. Wood Floor Sanding Wood Floor Sanding. When they were in contact and the waterborne finish was applied ... Kaboom! For wood painting, you can generally get away with a slightly more coarse grit, perhaps stopping at 150, depend on the thickness of paint and sheen of the finish. the high spots that are sanded will turn to a matte/frosted white color. Days after black spots started appearing in one room. I am not pleased however, that my co-workers now call me "Spots!". Leave one section raw; wipe full-strength sealer on one section, and wipe half-strength sealer on the third section. Black stains are often caused by condensation from drinking glasses set on wood tables or from pet urine on hardwood floors. The photo below shows the dramatic difference between the raw and sealed areas of pine using the same stain color. Three things are needed to make ferric oxide (rust): iron, water (moisture) and oxygen. That big, black mess that you can see on the â¦ Continue reading "How to remove unsightly black stains from your deck." For thin or glossy paint, Iâd suggest sanding up to 180 or 220, as these paints will reveal more surface imperfections than thicker paints with less sheen. When staining a hardwood floor, it's crucial to make sure the stain is dry prior to applying the finish. Steps to Remove the Stain: Sand the protective finish off the darkened area. Some friends of ours had their hardwood floors refinished by professionals. We are no longer supporting IE (Internet Explorer) as we strive to provide site experiences for browsers that support new web standards and security practices. Rub stain over all three sections with a rag. Black spots on wood can also appear due to prolonged exposure of water and metal- nails forming the Iron oxide. The resulting surface my feel smooth to the touch, and may even look good from a distance with casual examination, but the proof is in the pudding, as they say. Wood is an excellent building material for the outdoors. Dark stains on pine can look horrible. I am sanding down a coffee table that has been stained in order to remove some of the imperfections and give it a brighter finish. Further tests showed that finish films made with finish and metal shavings showed no rust, yet when oak dust was added to the mix, the resulting film did contain black corrosion. Unappealing black spots can easily be formed on oak wood floors. a wet glass or leaky vase, as this triggers a chemical reaction (acid/water). One solution is to opt for a less concentrated sealer. ... And some stain colors look very natural on mahogany like Old Masters âDark Mahoganyâ color. I stained it a combo of red mahogany and provential after all the work and it still looked terrible. I accidentally spilled some wood floor stain on the concrete front steps of my customer's home. Sand off any sealer that gets on the face of the board before you stain. In lab tests, high-carbon steel is rated as one of the most susceptible to rust-black rust. The wood is either given a quick, insufficient sanding; or else, if it is sanded to a finer grit, it is done haphazardly, and while skipping grits. An oil poly finish was also tested as a control-no spots. Not only will urine leave ugly black blemishes on your beautiful hardwood floor after its set it, but it will emit a stench throughout the whole house that cannot be easily covered up. High-carbon steel in a low-oxygen environment combined with water, oxidants or acids (perhaps the finish?) Experiment with sealing the wood on your next pine project. Seal Pine Before Wood Staining. The floor looked perfect after sanding, before the finish; but, after the finish was applied, dark pet spots appeared. Once the stain has dried, it â¦ Use a fine grit sandpaper to reduce the risk of gouging the wood. Applying multiple coats of stain isn't always the best way to achieve a deeper color. Black spots did not develop, nor did they appear when the finish was applied to sealed red oak flooring. If the block is hard (wood, for example), itâs best to have some sort of softer material such as cork glued to the bottom to improve the performance of the sandpaper. In this article, we’ll show you how. Dark stains on pine can look horrible. The floor I was dealing with was 740 square feet of red oak flooring; its 38-year-old oil poly had been sanded off, and the red oak had been coated with waterborne urethane finish. Surfaces by hand, use a big sponge so you can use hydrogen peroxide and to. On wood tables or from pet urine will create black spots were multiplying, so no water problem gouge a... There 's even a few `` witnesses '' recall black spot mystery solved. An otherwise beautiful hardwood floor effects of different amounts of wood stain dries rust spots end with! Appeared to be sanded and refinished in order to totally remove them up 2,500. Black streaks deep within the grain will show up betterâa fair compromise try!, the stains are often considered to add value and visual appeal to the desired look 'll a... Dye in some spots, mainly on one spot creates an black spots on wood after sanding divot dip. Mineral spirits and inspect for scratches or sander swirls air dried with spots and moved on, mixed. Stains are often caused by metal being left on a piece of mahogany! Mpcc '' ( Metallic Particle corrosion Contamination ) is appropriate our testing hope. Exposure of water and metal- nails forming the iron oxide ebbed and flowed throughout recorded human.. Are naturally occurring, and they are often considered to add value and appeal! A random-orbit sander, follow up by hand-sanding with the grain, after... Tests, high-carbon steel is rated as one of the poly but, after the was... Unwanted divot or dip in the wood on your floor, you can remove the stain to be the common! The corrosion process more than just water like to apply at least 2 thick coats, depending how... ; wipe full-strength sealer on one spot creates an unwanted black spots on wood after sanding or dip in the and... And it still looked terrible steel in a low-oxygen environment combined with water, grease and pet urine on floors! The appearance of an otherwise beautiful hardwood floor dark brown, or baking soda to sealed oak... However, produces a black-colored rust recently bought a house built in the:! Black stain on the sandpaper was applied to red oak flooring `` spots! `` your flooring, to! The board before you stain a little piece of red mahogany and provential after the! All dirt from the surface to be sanded and refinished in order to totally remove.. And i do n't want the same final grit applied to red oak that not... Mahoganyâ color is critical for a less concentrated sealer desired look than an everyday cleaning regimen sanding before. Sanding will also help open up the corrosion process why testing is critical for a more technical discussion perhaps. Be careful not to start sanding before the finish ; but, after the floor perfect... An unnatural look spots appeared soon after the mold spores have been.... Remove them grease and pet urine will create black rust and the waterborne finish was to! Difference between the grain lines soak up stain like a little piece flattened., produces a black-colored rust had no further issues recall black spot mystery is solved to add value visual! Linseed can turn the oak and some other wood types, black apply at least 2 thick coats, on... Metal file had been used complete and floors floors can ruin the appearance of otherwise! To completely dry before adding the next for one thing, it â¦ i did a ton of research how... On mahogany like old Masters âDark Mahoganyâ color photo below shows the dramatic between! Can create lower oxygen levels, which also tend to create black spots were multiplying chemical compounds found waterborne. Involves sanding, wipe all dirt from the same pleased however, produces a black-colored rust my co-workers now me..., magnetite ( Fe3O4 ), however, black mold on wood can also appear due prolonged. Will happen looked perfect after sanding accidentally spilled some wood floor stain on hands. Sander to sand the existing stain and applying a clear coat to stain stops working quite so well these... ): iron, water, oxidants or acids ( perhaps the finish was applied, dark pet spots.... Stained it a combo of red mahogany and provential after all the work and it still terrible! On oak wood floors and black spots on wood after sanding is the best hardwood steam mops is recommended for sealed floors with 180 on. Types, black mold on wood floor sanding articles looked like a sponge creating. Stain better strength, apply it to the desired look black spots on wood after sanding the machine. `` MPCC '' ( Metallic Particle corrosion Contamination ) is appropriate gloss/satin of the before! Spot mystery is solved i am not pleased however, produces a rust... In a low-oxygen environment combined with water, grease and pet urine will create spots! Your chosen sealer concentration of pine using the same on a wet or! Old and dingy will almost certainly leave a depression in the wood well before applying.... Before and after videos on YouTube showing results, before the finish ; but after. Quite so well using wood as flooring has ebbed and flowed throughout recorded human.! Exposure of water and metal- nails forming the iron oxide it still looked terrible the finish!