Furniture and woodwork are essential aspects of our indoor settings, whether they are in our homes or offices.
This furniture and woodworks have become not only a necessity but also a means of improving the appearance and aesthetics of our interiors, which is why people spend a fortune to keep them in good shape by applying polyurethane or lacquer over the surfaces.
Can you put polyurethane over lacquer?
You can put polyurethane over lacquer but it is not effective at protecting the lacquer layer and bonds poorly with it, thus it peels off over time. Polyurethane is also known to react with the lacquer layer to produce a messy finish and potentially damage the lacquer layer.
Polyurethane is a type of wood finish that is used on wooden surfaces to protect them from scratch and moisture-based damage.
Polyurethane is also popularly used on wood not only for its protective properties but also since it gives the wooden surface a glossy and smooth finish – improving the appearance of the wood while protecting it.
There are two types of polyurethane: Water-based polyurethane and Oil-based polyurethane.
Water-based polyurethane:
Water-based polyurethane is popularly used to coat wooden surfaces due to it being less toxic and having less pungent smell.
They dry much faster compared to oil-based polyurethane since they use a water base. However, they are poor against protecting the wood surface against heat and corrosive chemicals.
Oil-based polyurethane:
Oil-based polyurethane on the other hand is great against heat and chemicals and has a better durability than water-based polyurethanes in general.
Compared to water-based polyurethane, which are clear, oil-based ones have a slight color tone that compliments the wooden surface.
Lacquer is also a type of wood finish that consists of nitrocellulose and other solvents that allow it to form a thin protective layer on the wooden surface as well as give a glossy or matte coating.
Lacquer is popular on many furnishings due to its highly glossy finish that heightens the appearance as well as its high durability to scratches.
Layering different types of wood finishes is a popular and commonly used technique among many woodworkers.
Putting polyurethane over lacquer coating can be done but it is not as effective as other combinations of wood finishes. Since lacquer is water-resistant, water-based polyurethanes do not bind to the surface whereas the oil-based one binds fairly.
However, the polyurethane is not durable on the lacquer layer since their bonds aren’t that strong compared to other finishes. Which is why polyurethane is known to peel off the surface over time, exposing the lacquer beneath it.
Can you put lacquer over polyurethane?
Lacquer and polyurethane both have very different chemical composition and do not bond well with each other due to adhesion problems. Lacquer cannot be put over polyurethane unless a barrier coat is put in between such as vinyl sealers or dewaxed shellac after sanding the surface with a sandpaper.
Lacquer is a type of wood finish that uses nitrocellulose and other solvents to generate a thin protective layer on the wood surface as well as a glossy or matte finish.
Lacquer is widely used on furniture because of its very glossy surface, which enhances the aesthetic while also providing excellent scratch resistance.
Polyurethane is a form of wood finish that is applied to coat wooden surfaces from damage caused by scratches and water.
Polyurethane is also commonly used on wood, not only for its protective capabilities, but also because it provides a glossy and smooth finish to the wood, boosting its looks while also protecting it.
Water-based polyurethane:
Water-based polyurethane and oil-based polyurethane are the two forms of polyurethane.
Since it is less harmful and has a less unpleasant odor, water-based polyurethane is widely used to coat wooden surfaces. Because they are water-based, they dry faster than oil-based polyurethane.
They are, however, ineffective at protecting the wood surface from heat and corrosive elements.
Oil-based polyurethane:
Oil-based polyurethane, on the other hand, is more resistant to heat and chemicals, and it tends to last longer than water-based polyurethanes.
Oil-based polyurethane has a subtle color tone that complements the wooden surface, as opposed to water-based polyurethane, which is transparent.
Many woodworkers use a technique called layering to combine multiple types of wood finishes.
But in the case of putting lacquer over polyurethane, the process is not possible because not only do they have adhesion problems, which is why they don’t bind – but also polyurethane is a better finish. So putting lacquer over polyurethane is ineffective and inefficient.
Is lacquer water-based or oil-based?
Most wood finishes are dissolved in different types of solvents which demonstrate a varying level of performance on different species of wood. The two types of solvents are water and oil, both of them have their own set of pros and cons.
Lacquers are oil-based wood finishes where the oils emulsified the resin solution to form the finish called Lacquer.
They exhibit fast drying behaviors, as well as their formation of hard transparent film as they get exposed to air, are commonly seen in most water-based wood finishes.
Regardless of their similarities with water-based finishes, lacquer is an oil-based wood finish.
The lacquer layer coats a wooden surface as the oil in the mixture evaporates and the mixture undergoes a process called oxidation that alters the chemical composition of the lacquer.
The end result of the process removes all the oil, leaving a layer of solid resin which is known as the lacquer coat.
What finish can be applied over lacquer?
There are many varieties of wood finishes that can be applied over a lacquer coating, the types of finishes are explained below in detail:
Varnish:
Varnishes are transparent oil-based finishes that are very commonly used on lacquer layers. They are popularly used on floors, furniture and cabinets with a highly glossy appearance.
Varnishes are usually clear but sometimes they can show a slight orange tint. Varnishes can either be rolled, brushed or sprayed over the lacquer layer.
Polyurethane:
Polyurethanes are excellent wood finishes with high durability and moisture resistance. They come in both water-based and oil-based variants which have their own pros and cons.
Polyurethanes can be used over lacquer but requires a bit of extra care while coating since polyurethanes don’t easily stick to the lacquer coat.
Stain:
Stains are the most common wood finishes that contain color pigments, carriers and binders in them which allows them to coat over any type of wood finish.
Since stains do not suit all wood types, they are popularly used on top of other finishes such as lacquer.
How to apply polyurethane over lacquer?
The steps of applying polyurethane over a lacquer layer has been described in step by step below:
Sand the lacquer layer:
To ensure that the polyurethane sticks to the lacquer layer, you need to use a 220-grit to sand the surface of the lacquer in order to smoothen it out to apply the polyurethane.
It is suggested to use oil-based polyurethane since lacquers resist binding with water-based finishes.
Brush the polyurethane over the unapplied surface:
Once the sanding has been completed, you must start brushing the polyurethane from the edges to inwards in repeated gentle swipes. Make sure the thickness of the layers are consistent and leave no spot unswiped.
Instead of a brush, you can use a roller as well but that increases the chances of forming bubbles in the layer if you’re not careful enough.
Swiftly brush over to pop the bubbles:
Afterwards, you need to take your brush and make a fast swipe across the surface in one go to make sure the bubbles in the layer are popped. Repeat this process throughout the surface until there are no bubbles visible.
Is polyurethane better than lacquer?
There are many types of wood finishes available in the market, however not all finishes behave the same and one can perform better than the other. The reasons why polyurethane is a better wood finish has been listed below:
Better durability:
Oil-based Polyurethanes last a much longer time and are highly resistant against scratches and damage compared to lacquer.
Resistance to heat and chemicals:
Lacquer being lightweight – fails to be resistant against heat and chemicals which polyurethane reigns in.
Can use different variants based on need:
Polyurethanes come in both water and oil-based forms, so you can use its versatility to choose whether you want fast drying coat or durable coats – whereas lacquer provides fast drying at the cost of durability.
Final thoughts
Polyurethane can be applied over lacquer but it is advised not to do so, since it can’t protect the lacquer layer well. Besides, it fails to bind to the layer and comes off with use. It also reacts with lacquer, resulting in a ragged surface with the possibility for the lacquer layer to be damaged.