How Primer Actually Works — Adhesion, Bonding & the Science Behind a Solid Finish

Ep19 How Primer Actually Works - Adhesion, Binding And The Science Behind A Solid Finish

Val Frania Hey, friends, welcome back to Flipping Furniture for Profit. I'm your host, Val Frania. And today we're rolling up our sleeves and diving into the two things that can make even the calmest furniture flipper lose all sense of sanctification, bleed- through, and bonding failure. Ah, if you've ever had yellow spots show up after you've already staged and photographed the thing, or if your paint has ever peeled off like a sunburn, oh my dear, you're in the right place today. By the end of this episode, you're going to understand exactly why these things happen, how primer fixes them, and how to protect yourself and your clients from ever having to deal with them again. We're going to talk about cure times, VOCs, safety, what to sand and what not to sand, when to spray versus brush. And I'll tell you a story about a custom project disaster that still haunts me. So let's start with the big one. What bleed- through actually is - the simple science version. Bleed through feels mysterious until you finally understand what's really happening. People think it's bad paint, or they didn't clean well enough, or the moon wasn't in the right phase. But bleed through is simply wood being wood. Inside wood are tannins, oils, pigments, all kinds of natural colorants. And when you paint over wood, these tannins want to rise to the surface like bubbles in a pancake batter. And when they do, you get those little dots that we've been talking about, that pink haze, those really awful orange streaks, or the knot rings that look like you're playing a whack a mole with stains. And here's the thing. You didn't do anything wrong. This it's not a skill problem. It's simply a primer problem. So why does primer stop bleed through? Shellac based and oil based primers are like building a wall, a real wall, brick, mortar, fortified, can survive a midwest winter, type wall. Once that barrier is in place, tannins can't pass through. They hit that sealed surface and say, "Well, guess we'll just stay down here then." Water based primer, on the other hand, is more like a screen door. It's useful. It has its place, but it isn't stopping anything. That's why warm toned woods almost always require shellac or an oil based primer. Pine, Oak, cherry. They're all loud talkers. They announce themselves to the world through your paint. But with the right primer. Silence. So let's list the woods that will betray you first. Pine is the worst offender. Oak is a close second. Cedar. Cherry. Mahogany. Knotty anything. If the wood leans warm, tannins are going to try and make a cameo appearance in your paint job, and often it doesn't even show up until you've put the poly acrylic, or the polyurethane on, and then it bleeds through, or maybe even months later or years later. The rule here is simple if the wood looks warm, assume it's going to bleed. Don't gamble. Prime it. You can stop bleed through before it starts. The actual process is easy. It just takes patience, which is why many beginners struggle. You clean the piece and then you scuff sand. I always recommend scuff sanding no matter what anybody else says. Okay. And then I clean it again because I want to definitely get rid of all of the the sanding particles. You put on your stain blocking primer of choice. Next you let it dry completely. If the stains peek back at you, you hit it again. Then you paint like normal. It's predictable. It's preventable. It works every time. I once fixed a yellow streak on my daughter's end table. With a three second blast of primer from a rattle can. She thought she'd have to repaint the whole thing. Sometimes the simplest fix really is the right one. Now let's talk about bonding failure. The peeling. When you scratch it, it comes off chipping. Bubbling paint. Bonding failure is a whole different beast. This is when you paint something that looks beautiful. You go grab it later and the paint scratches right off with your fingernail. Or worse, it peels off in sheets like a sticker. Or you see bubbles popping up everywhere. And every single time this happens, it comes down to one of these issues. The surface was too slick, or the primer wasn't the right type, or it wasn't used at all, or the primer wasn't fully dry before the paint went on top. Now let's talk about number three for a moment, because it's one beginners rarely think about. If you ever see bubbles forming under your paint, that's usually off gassing. What happens is this the layer underneath, whether it's primer or previous coat of paint, is still releasing gases as it dries. If you apply your next coat too soon, that gas gets trapped underneath and as it tries to escape, it lifts your paint and creates bubbles or even small blisters. You'll see that a lot with spray painting as well. Make sure you read the can. There's specific times that you can recoat and times you cannot. Ask me how I know. But it's not a product issue. It's not bad paint issue. It's a timing issue. And when you combine premature recoating with a slick surface, you know, like factory finishes, laminates, melamine, you know, Ikea furniture. The problem doubles. Some of those surfaces are so smooth that the paint will cling for a moment and then let go. This is where bonding primer becomes your best friend. Bonding primer grabs onto slick surfaces so your paint doesn't have to fight to stay put. It gives the surface what we call, "tooth." It evens out differences in sheen and creates a stable foundation for every layer that you add thereafter. In other words, if adhesion is a problem, bonding primer is a miracle worker. Here is a disaster story that I want to share with you about a custom desk. It happens far more often than anyone likes to admit. A client hires you to redesign a desk for her teenage son. She's excited. He's excited. You're excited for the job. You bring the desk home. The finish looks fine. Nothing too glossy, nothing scary. You clean it and you paint it navy blue. Honestly, you nailed it. You deliver it. Everyone's thrilled. You head home feeling like superwoman. Two days later, your phone buzzes. Hi. I'm so sorry, but the pain on the drawer front is peeling off. My son walked past it and the metal on his jeans scratched it and the paint lifted instantly. You know, there was a slick surface involved and bonding primer was skipped. But here's the kicker even if you had primed it correctly, they needed to be more careful with that piece because it had just been painted. Which brings me to something that separates beginners from professionals. Cure time is a hidden variable that most people don't even know about, let alone talk about. Paint dries fast, but it doesn't cure fast. Dry means you can touch it. Cured means you can use it. Most paints take two to four weeks to fully cure. During that time, anything can imprint. Books. Decor. Baskets. Coffee mug your dog brushing against it. Teenager throwing his backpack on it. If you don't educate clients about cure time, they'll assume the finish is weak or the paint is bad when really the piece was simply just used too soon. Here's your tip give every client a care sheet. It'll save your sanity. A care sheet is one of the best things you can do as a business owner. It not only protects the finish, it protects you. your reputation. It sets expectations. It communicates professionalism. And if the client misuses a piece, it's not your fault because you informed them. Tell them how long to wait before placing anything on it. Leaning against it. Bumping into it. Tell them how to clean it. What not to use to clean it, what environmental conditions matter, why they shouldn't drag things across the surface. People want to do the right thing. They don't know unless you tell them. When you understand why primer works for bonding, you don't need a chemistry degree. You will have much more confidence in your product. Primer works because it creates microscopic texture. We call it, "tooth," that gives the paint something to grip. Bonding primer does really go a step further. It actually contains adhesion promoters that grab slick surfaces. It's like the difference between trying to climb a smooth wall versus one with little ledges. The paint needs some foothold. Primer gives it the footholds. Now let's let's talk about VOCs and safety and mass. Please don't forget your lungs, because shellac based and oil based primers can knock you flat if you're not prepared. You need to protect yourself. Shellac has a very strong odor. Oil based has lingering fumes. Both require ventilation. I personally use a PM respirator any time I'm working with shellac or oil based products. Gloves, to windows open, fans going. It's worth the extra step. DHS installed an exhaust fan in the wall of our garage that sits right inside our spray spray tent. I have a video showing what he did. If you'd like to take a look, just message me. Water based primers, of course, are kinder, gentler cousins. But they're not the ones battling tannins or gripping to the laminate, so the strong stuff has its place. Have you ever considered spraying your primer? But you know both methods are completely valid. I usually brush a water based primer if DH isn't available, due to no setup time and not liking to use an oil based smelly primer. D.H., on the other hand, sprays most of our primer using oil based primer, a metal gun, and a compressor. It's faster, smoother and efficient, but since it's oil based, it requires ventilation and cleanup. And yes, sometimes he thins it just a hair so it moves through the sprayer properly. But here's the rule don't over thin primer. The more you thin it, the less effective it is. The can will tell you not to thin it. Use just enough thinner for flow and follow the can instructions as to what to use for that. You'll find many comments online saying you should sand primer. Should you? Yes and no. You don't sand primer for adhesion. Primer already grips you sand primer only to smooth it. A quick light pass if you want a softer finish is fine, but if you sand through to bare wood, you've just opened a brand new spot that now needs to be sealed again. So go gentle. Primer is not meant to look perfect, it's meant to perform. The big picture, bleed- through and bonding are predictable. Once you understand how surfaces behave and how wood behaves, how primer behaves, you can avoid ninety percent of flipping headaches. Prep protects your finish. Primer protects your prep. Education protects your business. All right, friend, that's your deep dive into bleedthrough and bonding problems. The what, the why, and how to fix them. But next week we're getting really advanced. Episode twenty is where we talk about some of the things that even your more experienced flippers that have been doing it for years have no idea. We'll talk about how primer actually dies: how to know when a can is gone bad. Ask me about the time it tried to attack me. Sanding myths, thinning rules, spraying secrets, VOCs that could knock over a horse, and the kind of, "I wish someone told me this earlier," lessons that even experienced flippers miss, don't even know to ask about. It's part science, part storytelling, and part confession from my own workshop mishaps. So definitely don't miss that. And as always, if you want deeper support, training, community, and step by step help, I'd love to welcome you into the Furniture Flipping Blueprint. You don't have to learn this craft alone. And to make this series super simple for you, I created a printable workbook that goes along with episode sixteen through twenty. It lets you listen without scrambling for notes, and later you can look through the checklists and extra pages I put together to help everything "click." If you'd like me to send it straight to your email, just head over there. ValFrania. com forward slash primer workbook and see you next week. And trust me. Episode twenty is a good one. Take care.