Knot bleeding happens when the resin solvents evaporate through the paint film and thus leave a less attractive, brownish finish. Unfortunately, woods such as pine, spruce, and fir have resin knots and are susceptible to knots bleeding through the paint. Therefore, you may end up with a failed product. So, let’s discuss the topic of how to stop knots bleeding through paint.
You can stop knot bleeding with Shellac. However, please ensure that you apply it on bare wood knots for a better result. In addition, apply a solvent-based primer-sealer or a transparent or semi-transparent coating before the topcoat.
You can remove dried resin by scraping it off or by heating the knot. Then, remove the residues with wood alcohol. This move helps to prevent further bleeding. Also, please read through this piece for more information about knots bleeding and the best courses of action when it occurs.
How Do You Seal Knots In Wood for Painting?
It would be best to seal all knots when painting bare wood. Fortunately, Shellac-based primers are perfect for the job as they seal wood knots and sap streaks. The formula carries a pungent smell but dries very fast and prevents the knot from bleeding through the paint finish.
Manufacturers will always give directions on how to apply the sealer. However, some brands lack detailed guidelines. Thus, please check out the following procedure to get the best out of the product.
- Inspect the Problem Areas
The first step is to check the wood for any knots on the surface. The knots are easy to identify as they are circular with different hues. Also, the wood grain usually flows around them. Thus, it is quite easy to spot them on the surface.
Softer woods like fir, pine, and spruce often have more knots. You will also observe that the lower the cost of the lumber, the more the knots on the surface. In addition, knots cause issues with wood appearance and strength. Therefore, a lower grade wood is more likely to have knots.
Even so, you may like the appearance of these knots. And they may not pose a threat to your work. So, please assess the wood and decide if you can work with the existing knots.
- Check the Wood Moisture
Wood with high moisture levels can create problems with anything adhering to the surface. Hence, it would be best to check whether the wood is dry. However, the wood should be ready for use if you buy the wood from a well-ventilated store or live in a dry climate.
In addition, please allow the wood to dry for about 48 hours before use if you got it from a moist shed or outside. You can also get a wood moisture measuring device to help identify wet wood.
- Scrape the Lumber and Apply Heat
Fresher lumber’s grain has resins and oils that squeeze from the fiber with time. Further, these components dry up as the wood ages and dries. Therefore, you need to scrap the dried resin before painting the surface.
Also, you can consider working with a heat gun for fresh wood with strong knots. The heat dries up the wood quickly and forces it to squeeze out the resin. Then, scrape the resin gently to avoid damaging or gouging the lumber.
- Clean the Surface
This step is usually optional. But it would be best to assess the wood before making a decision. For instance, use a little thinner or turpentine and a rag to clean the surface when the wood is tacky or sticky.
Additional dirt coatings make it difficult for the paint to adhere to the wood. Therefore, please wipe the surface anyway, even if it looks clean.
- Sand the Wood as Normal
Here, we get into the normal preparation strategy. Sand the wood to eliminate smaller resin fragments and rough areas. Also, it would be best to focus on the wood knots they can shift from their original cut and protrude.
Remember that the knot may be sharp and harder. Thus, the sandpaper will take more of a beating. However, sanding the surface well will tend the knot and deliver a desirable finish.
- Apply the Paint
There are various paints in the market. Better still, we have hybrid formulas that deliver sophisticated and expert results. Therefore, you will get the most suitable product for your wood.
Apply the paint following the wood pattern and grain or your intended design. In addition, please pay attention to the wood knots as they may soak up the formula more than the other wood areas.
Wait for the recommended duration before adding another coat. Then, repeat the application process. Also, you can apply as many layers as you need to deliver your perfect finish.
How Do You Treat Knots Before Painting?
The first thing to do when dealing with knots is to scrape away excess resin. Usually, the oils and resin from the wood squeeze out and settle on the surface. Thus, you will observe dried resin on the surface.
Then, heat the knots with a heat gun and scrape away the excess resin again. Also, it would be best to wash the surface with turpentine or a thinner. This way, you eliminate a sticky or tacky feel that could compromise your results.
Also, rough sand spots on the surface and then vacuum up the dust. This exercise helps to remove dirt and debris that might compromise paint adhesion. You can also get a lint-free cloth to wipe the wood.
On top of that, please note that lumber with high moisture will eventually compromise your project. Thus, please check if the wood is dry before using a knotting formula or primer. You can also allow the wood 48 hours to dry if you are unsure of its moisture content levels. So, you’ll not risk a failed product.
Lastly, it is prudent to do a thorough examination to confirm that the wood has knots. Fortunately, the knots are easy to identify as they are circular with various colors. Also, you see the wood grain flowing around them.
This practice will help you determine whether you’ll begin by scraping off dried resin or heat the knot. In addition, you may even find the knots attractive on your pine wood. And decide to leave them alone.
How Do You Waterproof Knots in Wood?
A water sealer is usually a perfect strategy to waterproof knots in the wood. It protects the lumber and creates a barrier from moisture. In addition, it makes the surface stain and scratch-resistant, and you enjoy a perfect surface for a long duration.
Please consider applying at least two coats of sealer on raw wood. This way, you’ll maximize the formula’s attributes. Also, you can apply a primer to enhance adhesion before adding a paint coat.
Remember that water is an enemy to wood. In other words, wood fails very quickly in areas with excess moisture. Therefore, please avoid allowing water to seep into the wood fiber by sealing the wood.
Also, water is still a threat to lumber even if you live in a drier part of the country. At some point, every state gets some rainfall. In addition, it does not have to heavy downpour to harm your wood. The wood fibers soak in the moisture slowly and gradually fail.
Why Do Knots In Wood Come Through Paint?
It is very common to see knots showing through after paint application. However, the major reason is that the wood is too old. So, the resins seep through the surface and cause discoloration.
Additionally, you will observe bleed-through in the wood knots in areas where you remove an old finish. And since the lumber is likely to be old, the bare wood will appear slightly discolored.
Is Knotting Solution the Same as Shellac?
Knotting solutions are Shellac-based. But they are not the same product as Shellac. Some formulas will have additional compounds, while others will have fewer. Therefore, it would help to assess your product needs before purchasing a knotting solution.
A knotting solution works excellently in stabilizing resinous wood. Its main role is to prevent seepage from wood knots and keep the finish from discoloration or fading. Also, you’ll get better results by cleaning the surface before using the product.
More specifically, Patent Knotting Solution is a professional solution for sealing resinous wood areas. Also, it is Shellac-based and also seals knots before paint, wax, or polish application.
The formula is naturally brown, and you can overcoat with a lightly pigmented or clear finish. In addition, please shake it well before applying liberally to prepared bare lumber. Then, use a brush and apply one to two coats for a desirable result.
On top of that, allow each coat to dry well before adding another. Also, consider applying the formula more sparingly if you cover the treated area with a water-based coating system. Then, lightly rub the surface before overcoating.
Knotting solutions hold back extractive staining from resin bleeding through paint and knots. However, it does not stop actual resid exudation or paint film bubbling when the resin evaporates.
Fortunately, you can handle the scenario by heating the substrate gently. This way, you’ll mobilize the resin and later wipe it away with a rag. Also, please dip the rag in methylated spirits as it helps to exhaust the knot.
Even so, knotting issues need filling and drilling out. And sometimes, problematic resinous timber areas may need splicing or cutting out with timber. Also, it would be best to wait for about 30 minutes. Remember to shake well after use, get a lint-free cloth or brush, apply a liberal coat, and leave to cure.
How Long Does Knotting Solution Take to Dry?
Knotting solution takes five to ten minutes to dry to the touch. However, it would be prudent to wait for about thirty minutes before applying an additional coat. Also, please keep brushing to a minimum to avoid overworking the underlying film.
On top of that, the drying time relies on the product type, atmospheric humidity content, and temperature levels. For instance, the higher the humidity and lower the temperature, the longer the drying time.
Therefore, please consider checking the weather forecast before embarking on your project. The practice will help you save the best days and conditions and thus guarantee a successful project.
What Can I Use Instead of Knotting Solution?
Ronseal Knot Block Wood Primer &Undercoat is a perfect alternative for the knotting solution. It is a primer undercoat that seals the resin in the knots. Thus, it substitutes the knotting-solution stage.
The solution is a quick-drying product and flows on the surface easily. It also has a low odor. Thus, you can use it for interior applications. In addition, you do not need too much formula for your work. Two coats are enough to give a perfect finish.
Frequently Asked Questions
Below are some of the most common questions on the subject. Keep reading for more insight:
- Should You Avoid Wood Knots?
Yes. It would be best to avoid wood knots as they cause the wood fiber to flex at odd angles. They even create a dead point in the lumber. However, they are often in the wood’s structural strength. Thus, you’ll need some techniques to handle the issue.
You can use wood with many knots in areas where you need less force. For instance, use knotted wood for the backing slates if you are building a chair. Then, get proper wood for the legs or seat. Also, knotted wood would work well for the back of a dresser where you need little structure.
Surprisingly, they can add a nice twist to an otherwise dull look. Therefore, the decision to eliminate wood knots depends on the type of wood and project expectations.
- How Many Coats of Shellac Does it Take to Seal Knots?
You only need two coats of Shellac to seal knots. But first, sand the knot lightly to roughen up the surface and enhance adherence. Also, it would be best to allow each coat enough time to dry before adding another.
- How Do You Prime a Knotty Pine?
You can primer a knotty pine with a pigmented or oil-based Shellac primer. Usually, the product prevents bleeding and gives the surface a more even texture. In addition, wipe off any dust before priming for the primer to adhere well.
Also, please sand the surface sufficiently to enhance the primer’s adhesion to the wood. This way, you’ll create a solid base for your paint or stain.
- Can I Use Varnish Instead of Knotting Solution?
No. It is not advisable to use varnish instead of a knotting solution. Moreover, experts warn sternly against using just varnish over the knots. Therefore, you are safer if you get the recommended knotting product.
In addition, you have to sand the wood properly and seal it to prevent sap and knot bleed. Hence, it would be best to get a formula that seals the wood fibers. And unfortunately, vanish does not do an excellent job in sealing.
Therefore, please stick to a knotting solution like Shellac, as it coats knots perfectly. It will also prevent sap from oozing through the paint finish. And you’ll enjoy good-looking lumber for a long, long time.
Please consider finishing a shellacked knot with varnish if you want to have a varnished surface. This move guarantees that the knots and wood sap remain intact in the long run. However, you do not need to apply a knotting solution to raw lumber if you paint it with oil-based paint.
It’s all about learning your project requirements and product prescriptions. This way, you’ll know when to apply the knotting solution or whether to have it all.
- Can You Use Knotting Solution Under Water Based Primer?
Yes. It is possible to use a knotting solution under a water-based primer. After all, knotting compounds are at their best as a base undercoat on knots. They work well for all primers, unlike stains and varnishes that may deliver desirable results.
Also, it is always prudent to check the product manufacturer’s instructions concerning its application and general use. This way, you’ll follow the correct procedures and end up with an expert outcome.
Knots bleeding through paint are such a frustrating experience. Even worse, they make the wood surface look attractive and eventually deliver a failed product. This problem usually affects woods with knots containing resin. Therefore, it would be best to be extra careful when working with pine or spruce. Moreover, you can still get professional results if you learn how to:
How to Stop Knots Bleeding Through Paint.
You can prevent knots from bleeding through paint with Shellac. Roughen the surface to remove existing paint. Then, daub a coat of primer on the coats. This way, you seal the wood grain to prevent future bleeding.
Additionally, it would be best to remove dried resin by scrapping it off or by heating the knot. You can use a heat gun for better results. Also, wood alcohol does an excellent job of removing any residues from the surface.