How to Thin Polyurethane

We research in-depth and provide unbiased reviews and recommendations on the best products. We strive to give you the most accurate information. If you buy something through our links, we may earn a commission.

If you’re wondering how to thin polyurethane, you should know that there are several methods. One is to mix two parts mineral spirits with one part water. Usually, you will use the mineral spirits to thin oil-based polyurethane. You can also use water if the polyurethane is water-based. The best way to apply polyurethane is with a natural bristled brush. Apply the sealer with long strokes and make sure to smooth any drips or excess product.

Mineral spirit

Mineral spirits thins polyurethane by thinning it out. Polyurethane is a coating that protects wood and other surfaces from the elements. It is an oil-based coating that can be wiped off with a cloth or a flat stir stick. Mineral spirits can be used to remove any spots or stains, too. Mineral spirit is a caustic solvent, and it can be very sticky and should be used with care.

To use mineral spirits to thin polyurethane, open a can of polyurethane and add a few tablespoons of mineral spirit to the can. Stir the polyurethane thoroughly, making sure not to create bubbles in the mixture. Do not stir too fast, because this can cause trapped air bubbles, which will ruin your polyurethane coating. Once you’ve poured enough polyurethane in the can, add mineral spirits to make it thinner. Use a one-to-four ratio of mineral spirits to polyurethane, as this ratio is best for brushing.

While mineral spirits can be used to remove stains from polyurethane, it will not dissolve it. The solvent is only effective on oil-based polyurethane, so it’s not a good choice for water-based polyurethane. While mineral spirits is cheaper than paint thinner, it’s not safe for large surfaces. This solvent produces more fumes, and it should not be used on large surfaces.

If you don’t want to use mineral spirits, you can buy a water-based polyurethane and thin it with water. Mineral spirits has a low odor and is considered eco-friendly. It can also be used as a milk solvent. Mineral spirits thins polyurethane, but it won’t affect its quality. It will help to prevent bubbles from forming on the surface and will also dry the coating faster.

Aside from thinned-out polyurethane, mineral spirits is a useful tool for reviving an old finish. But before using mineral spirits, it’s a good idea to test it on an inconspicuous area first. After that, use a scotch-brite pad to wipe away any excess stain. After cleaning, you can use a thin coat of clear furniture wax to protect it and prevent the finish from becoming dull.

The other way to thin-out polyurethane is to use mineral spirits. Mineral spirits is a solvent that can be dissolved in water. The solvent will break down the polyurethane into smaller molecules that will attach to each other to form a polymer. This process can be repeated many times until the desired effect is achieved. These techniques are relatively safe, but they have their own set of risks. If you’re considering using mineral spirits on your project, be sure to read the instructions carefully.

The mineral spirits are very flammable and are considered hazardous waste when they are in liquid form. Fortunately, the vapors of these products are lessened with newer versions of mineral spirits. Still, it’s important to work in a well-ventilated space. If possible, wear a respirator, as mineral spirits are extremely flammable. However, they are not harmful when used on wood and other materials.

Read More:   How to Prevent Tear Out on Miter Saw

Another type of mineral spirits is naphtha. It is a petroleum distillate with higher solvent strength than mineral spirits but is much less oily. This is more effective for cleaning oily surfaces and thinning oil-based paints and varnishes. Mineral spirits also allows for more time to level the coating after brushing. Mineral spirits is also better for general-purpose cleaning. For example, you can use mineral spirits to clean your wood before applying the finish. It is also an excellent way to highlight flaws and temporarily change the color of wood.

In addition to thin polyurethane, mineral spirits can also be used to remove acrylic paints and nitrocellulose lacquer. Although shellac doesn’t react with petroleum, it does react with alcohol and cut it down to size. Although mineral spirits can be used to remove shellac, it should not be mixed with other substances. This can make it toxic. This product is best used to remove traces of shellac before applying the polyurethane.


If you’re working with polyurethane paint, you might be wondering how to thin it with mineral spirits. While this approach can work, it is not recommended for all circumstances. For instance, some states ban the use of mineral spirits in polyurethane paint due to safety concerns. For this reason, you should always wear protective gear, including a respirator-style mask and gloves. Also, you should avoid spilling anything, including mineral spirits, which can cause irritation to your skin.

Oil-based polyurethane is easy to thin with mineral spirits or denatured alcohol. Mineral spirits and naphtha are not as effective as paint thinner. Always thin the polyurethane with the correct amount of thinner. If you don’t, your finish won’t adhere properly to brush marks, and it will peel off and deform over time. If this happens, you’ll need to apply more coats to get the desired finish.

Naphtha is a common paint thinner. Its main difference from acetone is its lower volatility and lower VOC content. However, mineral spirits is still an excellent solvent for oil-based paints because it is widely available and relatively inexpensive. However, it is important to note that naphtha is more powerful than mineral spirits. Therefore, it is not recommended for use in hot environments.

Another major difference between mineral spirits and naphtha is that naphtha dries the polyurethane faster. This is not true, as the oil-based material requires two steps to dry, one to mix it with water and the other to dry. Once the polyurethane dries, it forms a crosslink with oxygen in the air. If you use mineral spirits, you’ll be able to keep the finish open for longer, thereby helping bubbles to pop.

Another natural solvent for polyurethane is mineral spirits. This is distilled petroleum that can be used as a medium for thinning. Turpentine, on the other hand, is a strong-smelling substance that is usually used by artists. While both are safe for use in a limited amount, you should always do so in a well-ventilated area. When using mineral spirits, make sure that you buy a solvent that is meant for polyurethane products.

If you’re wondering how to thin polyurethane with naphthane, you need to be aware that it will evaporate quicker than mineral spirits or turpentine. The faster the thinner evaporates, the faster the polyurethane will dry. It’s also worth noting that water-based polys tend to oxidize more quickly than naphtha. This means you’ll have to apply more layers of the coating before the poly starts hardening.

Read More:   How to Clean Bandsaw Tires

Before you spray polyurethane, you’ll need to make sure that the layer is as thin as possible. This way, you can avoid bubbles and uneven surfaces. To thin polyurethane, pour the mixture into a container and stir it slowly to avoid bubbles. Make sure that you’re not stirring too vigorously, though, as you’ll only be causing more of the substance to evaporate.

To thin water-based polyurethane, follow the same steps as with the water-based version. Start by loading a clean glass jar with the water-based polyurethane. The water-based version of the product needs to be at least two-thirds water to be fully effective. You can use this solution to dilute the polyurethane up to 10% or more.

Water-based polyurethane is more expensive than oil-based versions. It takes twelve hours to dry completely. In addition to using mineral spirits to thin it, water-based polyurethanes can form a thin skin over the surface. To create a water-based finish, you can also add tint to the polyurethane to give it a look of oil. You can apply TransTint Honey Amber to achieve this look.

Why trust Handyman.Guide?

s written by Itamar Ben-Dor, who has 25 years of experience in renovations, carpentry, locks, creation, landscaping, painting, furniture construction, and furniture renovation, works with concrete, plumbing, door repair, and more.

Itamar Ben-Dor has been in the home improvement business for over 25 years. Itamar Ben-Dor is a jack of all trades. He's worked in the renovation field for years, doing everything from locksmithing to carpentry. He's a small repairs specialist. But his true passion lies in furniture construction and renovation - he loves seeing old pieces come back to life with some new woodwork or a fresh coat of paint.

He has taken courses on many topics in these fields at professional colleges in Israel. Over the years, Itamar has also become quite skilled in gardening, carpentry, and renovations. He's worked on projects of all sizes, from massive renovations to small repairs. No job is too big or too small for him!

Disclosure: participates in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for publishers to earn fees by linking to and affiliated sites.