Whether you can apply polyurethane over another popular wood finish called polycrylic is a common question among woodworkers.
Getting the protection and aesthetic results we want from our projects demands understanding how different protective coats work alone and together.
Today, millions of DIYers and craftspeople choose between polyurethane and polycrylic for their woodworking projects.
Both offer advantages, but knowing their differences, properties, and how they can complement each other ensures you select the right combo for your specific needs.
In this comprehensive guide, we’ll explore the ins and outs of polyurethane and polycrylic. We’ll define each, outline their characteristics like application, drying time, durability and scratch-resistance.
We’ll also analyze where each shine on their own and where layering them provides benefits.
What is Polyurethane?
The history of polyurethane stretches back nearly a century, making it one of our most established and versatile wood finishing options.
Developed in the late 1930s by German chemists, its invention revolutionized protective coatings.
But what exactly is polyurethane? At its core, it consists of two primary building blocks – polymers and urethanes.
Polymers are large molecules that can be natural or synthetic. Examples woodworkers may be more familiar with include nylon, Teflon, and epoxy.
Urethanes occupy a chemical family close to plastics and rubber. When polymers and urethanes combine through a process called polymerization, they gain protective properties well-suited for wood surfaces.
This linkage is what gives the final product we know as “polyurethane” its character.
Early commercial uses of polyurethane included applications like shoe soles and mattresses where durability and flexibility were key.
During World War II, it was even utilized to shield aircraft interiors. As additional applications like rigid foams emerged, variations in hardness and tolerances broadened polyurethane’s scope.
Eventually, the finish’s proven track record safeguarding planes led to its evaluation as an outdoor wood protector.
Today, polyurethane stands as one of the most widely used protective sealants in woodworking shops and fabrication facilities globally. Applied as a topcoat, it forms a durable plastic shield against water, impacts and more.
Its simple two-part construction and proven longevity over the decades have made polyurethane exceptionally popular.
But delving deeper into its characteristics offers additional insights for determining the right product.
Types of Polyurethane
With polymers and urethanes comprising the base formulation, polyurethane requires an additional component – a carrier medium. This is what differentiates the two prevalent varieties experienced by most woodworkers.
The first is water-based polyurethane. As its name implies, these varieties employ water to dissolve and convey the polyurethane solids.
For hobbyists and small woodshops, water-based polyurethane reigns as the most commonly opted selection.
Its rapid drying properties within hours instead of days allows quicker turnarounds. However, multiple thin coats averaging three to five may be necessary to attain ideal protection levels. Newer “water lock” technologies attempt mitigating this through extra solids per coat.
On the other hand, stands oil-based polyurethane. These selections utilize non-water liquid petroleum or synthetic oils to carry polyurethane particles.
While offering competitive durability when cured thoroughly, oil-based polyurethane presents some cautionary attributes.
Namely, application and environment require greater attention due to oil-based polyurethane’s toxins like volatile organic compounds (VOCs).
Complete off-gassing typically demands 30 days instead of a week. Inhalation risks like respiratory irritation render respiratory protection compulsory.
Darkening tendencies over the lifetime of oil-based polyurethane brings further aesthetic tradeoffs versus potentially faster-drying water alternatives. Nonetheless, specialized high-solids variations aim achieving protection with less risk.
For most woodworkers and DIYers, water-based polyurethanes represent a safe first-choice due to easier handling.
But oil-based variants still carry importance, especially for flooring requiring more resilience against foot traffic and spills. New formulations also steadily close performance gaps.
Getting the protective and aesthetic qualities of polyurethane demands precise application. Several recognized techniques exist, each with advantages depending on project dimensions and builder preferences.
Brush application holds the distinction as an historically traditional approach. While susceptible to air bubbles if dragged, modern foam or synthetic bristles can circumvent issues. Careful tip-work assists smooth, even distribution of the finish.
An increasingly common alternative involves using a rag or cloth for wipe-on application. The lack of bristles means virtually no risk of imperfections like brush strokes. Polyurethane specially formulated for rubbing versus brushing expands flexibility.
However, the gold standard remains spray application. By affording the highest degree of control from a distance, spraying yields an immaculate end result.
An airbrush, HVLP spray gun or conventional sprayer sprays thin, overlapping coats to full coverage.
Proper thinning following manufacturer guidelines helps the coat atomize perfectly. Boxed or wheeled spraying stations protect other surfaces from potentially damaging overspray. Light sanding between 2-3 coats allows further sheen optionality.
Regardless of chosen administration technique, proper preparation like sanding and dust removal is imperative.
Multiple thin coats amounting to 3-5 applications appropriately applied and cured grants optimal protection for woodworking projects. With practice, any woodworker can flawlessly safeguardозд their creations.
By understanding application nuances, crafters can enjoy the durability, depth and beauty only polyurethane provides to countertops, furniture and more. Its venerable status remains due to continually meeting all protective needs.
Read Also: Can You Mix Satin and Gloss Polyurethane
What is Polycrylic?
Serving as a popular companion product to polyurethane, polycrylic delivers woodworkers another highly useful interior finish option.
Composed purely of water-based ingredients, polycrylic provides an eco-friendlier alternative for small crafts and furnishings.
Produced by a variety of manufacturers, Minwax Polycrylic stands as one of the most prominent commercial brands.
Offering quick dry times measured in hours rather than days, hobbyists appreciate polycrylic’s convenience without compromising notable protection levels.
While not fully waterproof, polycrylic successfully defends interior surfaces from moisture exposure and scratches that may occur through regular use.
Its resilient formulation shields wooden décor from impacts and scuffs without conspicuous blemishing.
Available across a spectrum of sheens from flat to high-gloss, polycrylic permits customizing a piece’s aesthetic character.
A water-clear formula suitable for most wood types preserves the natural luster below. Its low VOC emissions make application safer than oil-based competitors.
Due to 3-year durability ratings and defenses against yellowing under household stresses, polycrylic satisfies needs of furnishings, cabinets and trim without costly replacement. Cleanup remains very manageable using just soap and water.
While not as robust as advanced polyurethane systems, polycrylic provides more than enough protection for most low-traffic installations without polyurethane’s learning curve or hazard considerations. For small indoor crafts, its user-friendly nature supersedes all.
Comparing Polyurethane and Polycrylic
With differing attributes, the right choice between polyurethane and polycrylic depends on a project’s specific attributes and expected wear. Proper evaluation of protective needs assists selecting the most suitable match.
For furniture and surfaces receiving infrequent handling, polycrylic serves adequately through resilience and fast turnaround. Its friendly formulation appeals to beginners, while withstanding modest cosmetic challenges.
However, where wood may confront constant contact and potential abuse, polyurethane emerges as a wiser selection. Applied meticulously through spraying or multiple brush coats, it forms a superior moisture barrier and withstands wear from scratches, impacts and abrasions.
Additionally, polyurethane maintains optical clarity superior to polycrylic over prolonged UV exposure. Its protective plastic shell faces fewer risks of degrading under intensive applications such as floors dealing with traffic.
As a compromise, applying polyurethane over polycrylic capitalizes on each product’s strengths. Polycrylic delivers beautiful clarity and finish depth, while one to two topcoats of polyurethane augment durability and resistance toExact heating and staining for heavy-use household objects.
By analyzing protective specifications and review considerations, any woodworker can make informed choices for projects large or small. With matched expectations, both options satisfy protection needs through their specialized attributes.
Using Them Together
For applications demanding heightened protection without compromising aesthetics, combining polycrylic and polyurethane proves a viable strategy.
Layering their unique shielding aspects produces a finished assembly greater than its parts.
As a base foundation, polycrylic offers unparalleled clarity to accentuate woods’ textures and grains. Its uncomplicated application allows the natural substrate to shine under a clear, smooth application resembling glass.
Once fully dried within hours, following with 1-2 topcoats of polyurethane seals the substrate and polycrylic below. In doing so, polyurethane augments resistance to potential insults that may penetrate polycrylic alone over decades of exposure and handling.
Its durable thermoset plastic surface defends against heat, moisture penetration and damage from abrasion or impacts over long-lasting furniture, cabinets and millwork. All while permitting the substrate’s beauty to radiate unattenuated.
Properly applied according to drying schedules, the tandem approach maximizes both products’ strengths without compromise.
Hobbyists and professionals gain unmatched protection for valuable pieces through meticulous, multi-step finishing.
Whether high-use dining tables, family room décor or commercial installations, judicious layering gives owners confidence their wooden assets will endure for generations of enjoyment and appreciation. Combined finishing simply provides the most comprehensive safeguard available.
Benefits for Specific Projects
Analyzing protective film attributes assists pairing the right combination to a project’s unique usage characteristics. Here we examine where standalone or combined systems shine.
For furniture subject to minor marring like end tables and desks, polycrylic alone suffices through resilience and accelerated drying. Pecan sideboards or accent pieces stored upright also perform well underneath its shield.
However, dining surfaces bracing regular dinnerware use necessitate polyurethane’s formidable barrier. Three or more full-bodied coats block indentations and stains that compromise wood fibers.
Cabinet interiors sheltering foodstuffs likewise warrant polyurethane’s impermeability. Even nail polish or wine spills pose minimal risk to its infusible plastic skin.
Highest-traffic flooring demands diamond-hard durability through 5 coats of oil-based polyurethane minimum or a polycrylic base with 2 urethane topcoats. This rugged assembly protects plank investments for decades.
With informed selection, woodworkers empower diverse projects to thrive through accurate protective matching. Proper finishing elevates any creation from functional to fine art through stability against daily wear and tear.
Through exploring polyurethane, polycrylic and their combined implementation, we aim to have left no aspect of these versatile coatings unexplained.
Their distinctions across attributes like composition, drying properties and durability shape all finishing considerations.
While polycrylic offers a uniquely simplified solution for low-traffic indoor projects, polyurethane maintains a venerable role through unrivaled resilience.
Across all applications, its multidecade service protects materials investments far beyond expected lifespans.
By cross-analyzing specific installation parameters, any woodworker now feels equipped to formulate the ideal protective strategy.
Whether a single product or combined system, your projects stand protected under optimized formulas.
We hope demystifying these mainstays empowers new confidence in finishing. Through diligent preparation and application according to best practices, wooden creations will dazzle audiences for generations to come.