Cedar Acidic Tannin Extractive Bleeding and Staining: Prevent & Fix Paint Discoloration


Cedar is a popular siding material because of its beauty and its durability, but it has a natural acidic tannin that can ruin painted cedar through a process called extractive bleeding. Learn how paint discoloration and staining happens & how to prevent and fix it.

cedars acidic tannin extractive bleeding, how to prevent and fix paint discoloration

  Cedar Tannin Staining & Extractive Bleeding Explained: How to Prevent & Fix Painted Cedar Siding Discoloration on Your Home


This article should explain everything you need to know about painted cedar siding.
The goal is to educate homeowners about the complexities of exterior painting, especially when the paint job involves cedar shingles, shakes, clapboard or any type of cedar. As an exterior painting contractor I (Richard D’Angelo, founding owner-operator of Morris County, NJ home improvement contractor and house painter CraftPro Contracting) have seen many homes with paint discoloration and staining due to improper and insufficient painting techniques. Many exterior painters fail to properly treat cedar siding before painting it, but I don’t. Read on for a detailed, informative look at cedar’s acidic chemical ‘tannin’ and how it stains paint through a process called ‘extractive bleeding’. Learn the proper way to treat it. Learn about paint discoloration and how to prevent it. And if your painted cedar is bleeding and staining, learn how to fix it. Also learn my approach to exterior painting of homes with cedar siding and why I warranty my paint jobs for up to FIVE years: click here to jump to that section of this article.

  A Story About Extractive Bleeding and Cedar Tannin Stains…

  A Familiar and Common Scenario…

cedar clapboard with tannin bleeding

You just spent every weekend for over a month working yourself half to death painting the exterior of your house because you didn’t believe that exterior painting had to be done by professional painters and, after all, you’re very handy. You power-washed and you sanded, because you understood the need for thorough surface preparation before exterior painting – you knew that exterior painting isn’t just for looks, it’s for the protection of your home’s siding. You had done your research, and you were a true weekend warrior: waking up early and working late to execute the job. It took a long, long time to prep and paint that house and at the end you were thrilled with the brand-new look and the curb appeal provided by a fresh exterior paint job. Jump forward about a year when you look at your home: you’re shocked. Mortified. Horrified. There’s some type of discoloration going on. That bright white finish is compromised by a reddish-brown stain in spots and streaks all over your home. The idea of re-doing the entire project is too much to bear, so you just grab a brush and paint over the stained spots. ”Ok that’s better… I wonder what happened? Oh well…” In a matter of only a couple weeks the stains are back. Rather than throwing a fit, you remain calm because you’re an adult and now you decide to figure just what could have possibly happened to your beautiful cedar siding. One Google search later and ”Wait, what’s an ‘acidic tannin’?”

  About Cedar’s Acidic Tannin

beautiful cedar shakesCedar is a gorgeous wood, and it ought not be penalized for its chemical make-up. It is durable and it naturally resists decay, making it a popular choice for a home’s siding and, when maintained properly, it can last for a long time – multiple decades, even. However, cedar is among a group of woods (like Cyprus, Redwood and Mahogany) that have a natural acidic chemical called a tannin that can cause staining of the topcoat due to extractive bleeding, a natural occurrence caused by moisture in the wood: the water-soluble tannin leeches its way to the wood’s surface and bleeds through, causing unsightly discoloration and staining of the exterior paint or stain topcoat. The main reason for this is moisture – it is the vehicle that drives the tannin to the siding’s surface. Since the tannin is water-soluble it is important that the cedar’s moisture content is not too high (usually less than 15% moisture content is safest). Now you’re thinking, ”How am I supposed to know the moisture content of the cedar siding on my house?”. Firstly, when the cedar was milled, it should have been properly cured, allowing time for moisture to evaporate. Secondly, the cedar should have been primed with an appropriate oil-based tannin-stain-blocking primer on all sides and edges. Unfortunately, when new buildings were built decades ago, some builders cut corners and they skipped this crucial step. Now, as the homeowner, you’re stuck with inferior cedar siding. Not to worry: your local painting contractor – like CraftPro Contracting painters in Morristown, NJ 07960 – can be hired to execute a thorough painting job of your home in a way that minimizes the occurrence of cedar tannin staining caused by extractive bleeding or completely prevents it. Or, of course, you can try it yourself:

  How To Prevent Against and Fix Stains from Cedar Tannin

cedar clapboard with tannin staining

  • A quality painting contractor will thoroughly prepare your house by way of practices like power-washing and –sanding, among many others. These two specific practices cause failed paint exposure and removal and almost always lead to the presence of bare, raw wood. The bare cedar MUST be primed with two coats of an appropriate tannin-stain-blocking primer: oil-based, since water is the vehicle for the tannin, the oil-based primer will block it. Consult your local paint retailer for what product is best for your home’s specific siding, age, etc.
  • Being that moisture is the vehicle for extractive staining, caulk all gaps in the trim and elsewhere to prevent water from getting behind the siding. If you choose to caulk between shingles, make sure you use the right product: one that will expand and contract with the wood. This is critical. Regular caulk will fail when the wood expands and contracts, and you could end up with little caulk strings decorating your home’s siding. Maybe you’re into that sort of thing, if not: they make caulking products that are designed specifically for caulking between, say, cedar shakes (shingles).
  • If the tannin-stained paint is not lifted during power-washing or –sanding and still exists after prepwork then it needs to be cleaned with a scouring tool (e.g. a wired brush) and a 50/50 solution of denatured alcohol and water, rinsed thoroughly, allowed to dry and then primed with the tannin-stain-blocking primer.
  • You can choose to spot-prime bare wood and tannin-stained areas or you can apply full primer coverage – it depends on the severity of the tannin-staining (and your budget). Either way, all edges and sides of the cedar piece must be primed. The backs of the siding will (should) have been primed by the manufacturer or siding contractor before installation.
  • Nail bleeding and discoloration: If there is bleeding of the nails used to secure the cedar siding to the home then the wrong type of nail was used. Stainless steel or galvanized nails are critical for avoiding tannin staining of cedar siding. You can replace all the nails (“No way, not a chance” – you) or you can fill the nail hole with a water-repelling material and wood filler (after allowing the repellent to dry). Then spot prime the area, just to be safe.

Cedar tannin staining is a difficult thing to correct once it’s happened and it’s difficult to prevent, too. It’s complicated and it’s scientific, and most professionals agree that there’s no way to be completely certain your new exterior paint job will withstand the acidic tannin. We at CraftPro follow the practices listed above and have not yet encountered any tannin staining in our exterior painting projects, so if you (or your painting contractor) take the steps necessary toward properly preparing your siding so as to prevent it from tannin staining and discoloration you should not have any problems. If you choose to hire a professional painting contractor to tackle your painted cedar tannin stain issues (which I recommend, naturally) then make sure you get specifics on how they plan on addressing the issue. If he/she summarily dismisses the issue without giving it any consideration, he/she may not be the best choice for you. A good contractor, of any trade, takes customers’ concerns seriously. Good luck, and Happy Home Improving!

  Cedar Tannin Bleeding, Staining & Painted Siding Discoloration Needs Professional Help from a Qualified Painter

Getting ready to paint your New Jersey home? Do you have cedar siding? Have you had issues with cedar tannin bleed? Or are you just looking for an honest exterior painter who will provide a durable and beautiful paint job for a good price? Whatever your exterior painting needs may be, you’ve come to the right place. Let me (Richard D’Angelo, this article’s author and the founding owner-operator of CraftPro Contracting) help you. I’ll treat the extractive bleeding that’s causing problems with the paint on your home’s cedar siding. I’ll restore your home’s exterior with a high quality paint job that comes with a warranty of up to FIVE years. I warranty all of our paint jobs for this long (much longer than the industry standard of one year) because I know how to properly treat cedar and provide a beautiful and durable paint job. Other exterior painting contractors might skip the critical techniques and practices that protect painted cedar. This means you will have to pay for another paint job sooner than you need to. That isn’t how CraftPro paints homes. I will provide a paint job that lasts and lasts. You won’t have to have your home painted as often so you’ll save money. Fill out the form below to email me or call me at (973) 610-8763. I’ll provide over twenty references: my customers who have contributed to our 30 straight A grades on Angie’s List and all 5/5 stars on Google Reviews. I’m looking forward to hearing from you!


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