Stain and polyurethane are both excellent finishers for wooden surfaces. Polyurethane, unlike a stain, produces a higher-gloss surface. Their transparency allows the wood’s intrinsic beauty to come through by highlighting the grains. So, is mixing stain with polyurethane a good idea?
Both are easy to apply and have a quick finish time, making them high-demand products amongst woodworkers. Although, stains can have a limited number of colors available, which can make your task difficult if you are searching for a particular shade. Hence, polyurethane can be mixed with the stain to achieve different shades.
When mixing stain with polyurethane, you need to be careful to combine the formulas properly before applying them. In this article, we will discuss important factors you should consider before mixing stain with polyurethane, as well as what both these finishes are and their properties.
Wood Stain and Its Types
A stain is a chemical that enhances or changes the hue of your wood’s original shade. Wood stain is made up of colorants that have been dissolved or suspended in a solvent. Water, petroleum distillate, alcohol, or finishing ingredients like shellac, varnish, polyurethane, or lacquer are common vehicles.
Colored or stained finishes do not usually permeate deeply into the pores of the wood, and as they decay or are removed, they may largely vanish. Pigments or dyes used in the stains can go deep into the wood to accentuate the grain, enhance existing tones, or change the color.
Pigments have larger molecules and are momentarily suspended in the solvent, normally settling out over time, whereas dyes are molecules that dissolve into the solvent. The term ‘transparent’ refers to stains that predominantly include dye, whereas ‘solid’ refers to stains that contain more pigment, i.e., they are more opaque.
Generally, dyes can stain fine-grained woods, such as maple or cherry, whereas pigments will not. The pores in fine-grained hardwoods are usually too small for pigments to deposit into. As a result, most pigment-based stains also contain a small quantity of a ‘binder,’ which aids in the adhesion of the pigments to the wood.
Linseed oil, a drying oil, is a common binder in wood stains. It is a non-toxic, natural oil that works well as a preservative for just about any wood finish or paint.
Wood stains normally give some level of protection for the wood from the damaging effects of the environment. Even still, most people use stains for cosmetic reasons rather than for protection. Natural alternatives to synthetic stains include combinations of coffee and water or coffee and vinegar.
Nonetheless, there are different types of stains available in the market, each giving a unique appearance to the wood they are used on. Some of these types are:
Gel stains have a high viscosity and, as a result, do not flow. This makes them slightly easier to apply since they do not run or drip off the surface. Although, they do have less penetrating ability than other stains.
Because most gel stains are oil-based, mineral spirits should be used to thin and remove them. Their thickness, which is similar to mayonnaise, can be used to recognize them.
Gel stains are messy to apply, but if you want to tackle one of the most common difficulties in wood finishing, i.e., blotching on pine, they are an excellent option.
Oil stains are widely used and often the first choice that comes to mind when people think of staining their furniture or other wood projects.
They often use a linseed oil binder or a combination of varnish and linseed oil. This makes them simple to use since any excess stains can be removed before it dries, even if you are working on a relatively large project.
Solvents such as paint thinners or mineral spirits can be used to clean a stained wood surface.
The organic thinner is replaced with water in these stains, which use a water-based finish as a binder. As a result, these stains are less polluting, do not aggravate your skin when you touch them, and are, above all, easier to clean than oil and varnish stains. They dry much faster than most other stains available.
Varnish stains resemble oil stains in terms of appearance, with the only exception that they use just varnish, often polyurethane varnish, as a binder. This results in a harder finish than oil stain.
This results in a more durable finish since you can simply brush it onto the wood and let it dry without needing to wipe off any excess stain. In comparison, oil stains need to be wiped to prevent the top finish from chipping or peeling.
Lacquer stains use solvents and ultra-fast drying binders, such as xylene and ketones. Several professional finishers choose lacquer stains since they can be applied in fifteen minutes or less.
Since volatile solvents vaporize so quickly, they emit an odor. Various ketones and xylene have a very intense bitter odor, which makes them clearly distinguishable.
Lacquer is not used as a binding agent in these stains. Instead, they employ a short-oil varnish, which dries very quickly.
Metalized Dye Stain
Also known as metal complex dye stains, these are non-grain raising stains that are dissolved easily in fast-evaporating solvents and provide a great depth of color. They are ideal for bare woods.
They use glycol ether mixed with methanol, ethanol, or a retarder as a solvent. These types of strains can also be purchased in concentrated form, which can be diluted with alcohol, water, or any other lacquer thinner.
Polyurethane and Its Application as a Varnish or Adhesive
Before we get into mixing stain with polyurethane, we will discuss what polyurethane is and its properties as a varnish or an adhesive.
Polyurethane is a plastic that starts out as a liquid and then dries into a solid. Polyurethane comes in both water-based and oil-based forms, with finishes ranging from satin to glossy.
Polyurethane is a varnish that is extremely tough. When it dries, it has tiny chains of resin molecules that connect tightly together. As a result, you’ll get a finish that’s far more resistant to water, solvents, and abrasion. It’s a characteristic that most traditional varnishes lack.
What are Polyurethanes Used For?
Polyurethanes are used in a wide range of applications and benefits in the coatings, adhesives, sealants, and elastomers (CASE) sector. Polyurethane coatings can improve the aesthetic of a product while also extending its longevity.
Polyurethane adhesives have excellent bonding properties, whereas polyurethane sealants have tighter sealing properties. Polyurethane elastomers can be molded into practically any form, are lighter than metal, have better stress recovery, and can withstand a wide range of weather conditions.
Polyurethane binders can be used to bind a variety of grains and fibers together. Their main applications are in the production of wood panels, rubber flooring surfaces, and more. The most common use of polyurethane binders would be in the production of Oriented Strand Board (OSB).
Why Water-Based Polyurethane Is Better
The most popular polyurethane is water-based polyurethane, which has a low odor and few contaminants. Unlike oil-based variants, it goes on clean and dries with a transparent finish, i.e., it does not add any color.
Polyurethanes based on water dry much quicker. However, like shellac, it does not withstand heat and chemicals very well. As a result, it’s best for surfaces that are not exposed to harsh weather. This can include furniture such as desks, side tables, bookcases, or even wooden picture frames.
Oil-based or solvent-based polyurethane produces toxic fumes. They must be applied in well-ventilated areas, and can only be cleaning with solvents like mineral spirits. They are more durable than water-based polyurethane finishes. They are typically best when used for lighter wood colors, such as white oak maple or birch.
Coatings and adhesives that contain water as the principal solvent are known as waterborne polyurethane dispersions (PUDs). These are being employed in more commercial and industrial applications as regulations on the quantity of volatile organic compounds and toxic pollutants that can be discharged into the environment tighten.
Water-based polyurethane finishes do not require ventilation and can be easily cleaned with water soap, making them a better choice to work with than oil-based polyurethane finishes.
Can You Use Polyurethane Over Natural Wood?
Natural wooden surfaces have no stain or varnish. It is possible to use polyurethane on unstained wood, but sanding it is a prerequisite.
If you use 120-grit sandpaper, you can achieve great results. However, if you would like a glassier finish, it is better to progressively use finer sandpaper, going up to 220-grit.
Any further sanding is unnecessary and can cause the wood pores to close, which can, in turn, make polyurethane less effective.
Is It Possible to Stain Polyurethane Molding?
While mixing stain with polyurethane is one way to achieve your perfect finish, you might want to know whether you can stain a surface with polyurethane molding. Yes, polyurethane molding and its accent features can be stained or painted.
Prior to staining or painting, you need to ensure that the surface of the wood is clean. It allows the gel stain to adhere to the surface. Here are the steps to staining polyurethane molding:
Step 1: Getting a Clean Surface
Soak a cleaning pad into a 5-to-50 denatured alcohol-to-water solution.
Cleanse the surface of the wood to get rid of any grime, dirt, filth, wax, or other contaminants. Give it about two hours for drying.
Step 2: Sanding Your Surface
It is advisable to sand your wood surface by hand, using 400-grit sandpaper.
This roughens up the material, making it easier for the gel stain to adhere to it. Leave it to dry after wiping away the residual dirt or dust with a wet towel.
Step 3: Applying the Stain
Using a delicate cloth, spread the gel stain onto the surface.
Repeatedly fold the cloth, using a dry section of it for every stroke, to achieve a consistent, equal coating.
Step 4: Waiting for the Coat to Dry
The gel stain should be left to dry for at least 24 hours. Ideally, a gap of 48 hours should be given before another coat is applied.
You can reapply an additional stain coating if the color isn’t covered well or is too faint. In the end, you can finish it off with a second coat of polyurethane.
How to Mix Stain and Polyurethane
Mixing stain with polyurethane is a relatively simple procedure. The two finishes need to be stirred carefully. Here are the steps you can follow:
- Step 1: Mix the stain until everything is uniformly colored.
- Step 2: Using a mixing stick, stir the polyurethane finish.
This stage must be completed in a well-ventilated area as the mixture can produce harmful fumes, particularly if you’re using an oil-based polyurethane finish.
- Step 3: Divide the two chemicals into even portions and place them in two distinct, labelled containers.
- Step 4: Mix thoroughly until both the finishes are well-combined and the mixture is evenly colored.
In the final step, you should seal the container and label it according to the pigment color for reference in the future. If you store the mixture for a few days, you should properly stir it prior to any use.
Mixing Stain with Polyurethane: What to Know
When mixing stain with polyurethane, take a look at the type of wood you’ll be working with before you begin.
Rare woods such as mahogany, maple, rosewood, aged pine, and others should not be used because they are most valued in their natural color.
If you want to preserve the natural color of your wood, you should consider using a water-based polyurethane finish as it gives a clear or neutral finish when it dries. Although, it can leave grain on the wood; so you need to be cautious.
Here are some other things you should know when mixing stain with polyurethane and using them on any wooden surface:
- You should prepare your surface to get rid of any residual wax, dust, existing grain, or pollutants.
- Inspect the surface for any holes, splinters, or screws. You can use wood putty to fill the holes, sand down any splinters, and remove protruding nails or screws. An even surface will be easier to work with.
- When sand down the surface, remember to sand in the direction of the grain. A lint-free cloth is ideal for wiping it down to remove any dirt or dust.
- When applying any stain, use overlapping brush strokes. You might need to apply several coats in order to achieve the shade you desire.
- In between each coat of satin, remember to wipe down any excess product with a clean, lint-free cloth.
- You can wrap your brush with saran wrap in between each coat to prevent it from drying out.
- The stain and polyurethane mixture needs to be mixed thoroughly before each use.
Other questions you might have about mixing stain with polyurethane can be:
What Kind of Stain Can Be Mixed with Polyurethane?
There are numerous types of stains, so when mixing stain with polyurethane, you should know your best options.
Oil-based stains are relatively easier to mix than others since they have linseed oil. It dries slower, allowing you to easily remove any excess stain in time.
Water-based stains have a water-based finish to bind the stain and can be removed with water instead of organic thinner. The advantage they have over oil-based stains is that they are easier to clean, non-toxic, and dry much faster.
Gel stains work only with polyurethane finishes. It sticks on any other finish, i.e., shellac, lacquer, or varnish; hence it cannot be mixed with them. It is occasionally applied over polyurethane since it does not have penetrating properties.
It acts more like opaque paint, allowing you to change the color of your surface without stripping. Moreover, you will not get grain patterns with gel stains as compared to other stains.
Which Type of Polyurethane Can Be Mixed with Stain?
Stain can easily be mixed with water-based polyurethane without any risk of toxic fumes being emitted into the air. Moreover, it dries with a clear finish, allowing you to preserve the natural hue of your wooden surface.
Oil-based polyurethane can be mixed only with oil-based stains. Water-based stains will not mix properly with them since oil and water are immiscible liquids, i.e., cannot be mixed.
Can Water-Based Polyurethane Be Used?
Yes, if the stain is water-based. Oil stains, on the other hand, cannot be blended with water-based polyurethanes due to the oil’s natural property to separate from the water.
Alternatively, you could apply an oil-based stain on top of the previous coat of water-based polyurethane. When applying a water-based protection finish, the pre-existing finish must be completely dry.
What Can I Do to Prevent Grain Raising?
If you do not like the textured feel of wood, you might want to know how to prevent grain raising. When numerous layers of lacquer are applied, the high grain is not a problem since the lacquer adheres to it, resulting in a smoother surface.
If you want to avoid grain on your surface, keep the following points in mind when mixing stain and polyurethane:
- Make sure you don’t leave the pigment coating on the wooden surface for too long. The color will darken the longer the mixture is left on.
- Water-based and oil-based formulas cannot be mixed, and vice versa.
- Test any color or layer you’re thinking about on an unobtrusive area to make sure the final pigment matches the natural shade of the wood.
Because oil-based paints turn amber with time, avoid using them alongside light or white hues.
How To Mix Oil-Based Stain with Oil-Based Polyurethane
Mixing stains with polyurethane can give you special effects, such as antique age spots when you use oil-based products. There are numerous products that combine stains and polyurethane into one for easy application. To mix an oil stain with oil-based polyurethane yourself, you can follow these steps.
- Step 1: Fill a white plate or tray with the amount of oil-based polyurethane you’ll need. Because the tray is white, you can see the precise color of the surface coating you made.
- Step 2: Select an oil stain and add a few drops to the tray with the polyurethane. A darker shade will result in a better look than a lighter stain.
- Step 3: Mix both the ingredients until an even color is obtained to your liking.
- Step 4: The finish should be clear and transparent. Test it out on an area of the surface and wait for it to dry. If you’re satisfied with the outlook, you can apply it to the rest of the surface. If not, you can keep mixing stain and polyurethane until you get the finish you want.
If you have both of these finishes on hand, mixing stain and polyurethane can give you a glossier finish while allowing the wood’s natural beauty to shine through since they are transparent. Mixing stain and polyurethane also saves you time since it’s a one-off application. Other than providing a gorgeous surface, if applied correctly, they also protect your wooden structure for a long period of time.