Polyurethane or epoxy resin doming – which type of resin technology to choose for 3D domed stickers?

When deciding to produce 3D domed stickers, one of the key technical choices that every investor or marketing specialist must face is the type of resin used to coat the print. In the modern domed stickers printing industry, two main technologies dominate: polyurethane doming and epoxy doming.

Although both methods aim to achieve a convex, spatial effect, the differences between them are fundamental – both in terms of the production process itself and, most importantly, the final durability and aesthetics of the product.

Many manufacturers tempt buyers with a low price point, offering epoxy doming that performs well in controlled office conditions but surrenders when faced with UV rays and harsh outdoor environments. Polyurethane, on the other hand, has become the market standard for premium brands that cannot afford to compromise on durability.

In this article, we shed light on the technical differences between the two types of resin and offer guidance on which will be the best investment for your project.

What exactly is doming technology?

Before we move on to comparing specific types of resins, it is worth understanding what the process of creating 3D stickers actually involves. Doming is a specialised method of refining printed labels by applying a precisely measured layer of clear resin onto their surface.

Thanks to the physical phenomenon of surface tension, the liquid resin spreads perfectly to the edges of the sticker, stopping exactly at its contour and creating a characteristic, transparent “dome” (hence the name of the technology, derived from the English word dome). This layer performs two main functions:

1. Aesthetic: It adds an attractive, 3D appearance and incredible depth of colour to the graphics, creating a “magnifying glass” effect. The colours become more saturated and the whole label gains a premium character.
2. Protective: It acts as a solid barrier protecting the print against mechanical damage, scratches, and the influence of external factors.

However, for this effect to be permanent and truly aesthetic, the choice of the appropriate chemical material from which the “dome” will be made is crucial.

Epoxy doming – an economical but risky choice

Epoxy resins were the first to be used on a massive scale in the production of convex stickers. Their main advantage, which still attracts some manufacturers and price-oriented customers today, is primarily the lower cost of the raw material and a relatively simple application process that does not require such restrictive environmental conditions as modern alternatives. For many years, this was the basic standard in the production of 3D stickers, but along with the development of technology and the observation of products over time, its numerous drawbacks began to be noticed.

Detailed characteristics of epoxy doming:

• Hardness and rigidity: After the curing process is complete, epoxy resin usually becomes very hard and completely inflexible. While this might seem like an advantage at first glance, in practice, it means the sticker is suitable for application only on perfectly flat surfaces. Any attempt to bend the sticker or apply it to a rounded surface may result in the resin delaminating from the self-adhesive substrate or the surface cracking.
• The problem of yellowing: This is the biggest and most serious drawback of this technology. Epoxy resins are naturally not resistant to UV radiation. Under the influence of even small amounts of daylight, the clear layer begins to undergo a chemical reaction that causes it to turn yellow or even brown over time. This significantly spoils the aesthetics of the print, especially on white or light backgrounds, making the sticker look old, dirty, and neglected after just a few months of use.
• Brittleness and ageing: Over time, especially when exposed to fluctuations in temperature (e.g. in rooms that are heated in winter and cooled in summer), epoxy resin can become brittle. This leads to micro-cracking of the surface, loss of the original gloss, or even the complete crumbling of the resin layer.

Due to these properties, epoxy stickers are currently recommended by specialists mainly for short-term, low-budget indoor use, in places where they will definitely not be exposed to direct sunlight or varying thermal conditions.

Polyurethane doming – the premium standard in the industry

Polyurethane resin is currently considered by experts and professional printing houses to be the best and most professional material for the production of 3D stickers. Although the raw material itself is pricier and its processing requires much more precise production conditions (such as strictly controlled air humidity and constant temperature in the production hall), the final quality and multi-year durability fully compensate for the higher initial costs.

Advantages of polyurethane doming in detail:

Safety and Ecology (Mercury-free): High-quality polyurethane resins (such as those used at Polinal) do not contain toxic mercury compounds. This is a crucial aspect, as cheaper substitutes and low-quality resins often contain substances that can be harmful to health and the environment. This is important for both the safety of the production staff and the end users of the products.

Full UV Resistance: Polyurethane is completely resistant to the harmful effects of ultraviolet radiation. This means that stickers do not yellow even after many years of intensive exposure to the sun. They remain perfectly clear and transparent, protecting the colours of the print for a long time. This is the most important feature for companies that care about the long-term, professional aesthetic appearance of their branding.

Exceptional Flexibility and “Memory”: The resin remains flexible even after the curing process is fully complete. The sticker can be bent, and the “dome” has a unique “self-healing” property – if indented with a fingernail or a sharp object, the surface returns to its original, smooth shape after a while. This flexibility also makes it ideal for application on slightly curved or uneven surfaces, such as electronic equipment casings, household appliances, or car bodies.

Incredible Durability and Resistance: Polyurethane is fully resistant to difficult weather conditions, constant moisture, and many chemicals (e.g. cleaning agents). It does not crack, does not crumble, and does not lose its high gloss even after long-term use in an external environment.

Comparison: Polyurethane vs Epoxy Resin Labels

Feature	Polyurethane Resin	Epoxy Resin
UV Resistance	High (remains crystal clear for years)	Low (yellows quickly under light)
Flexibility	Permanently flexible	Hard and brittle
“Self-healing” effect	Yes (removes surface dents)	No (permanent scratches and cracks)
Durability	Many years of life (also outdoors)	Short-term (months, mainly indoors)
Application	Universal (indoor and outdoor)	Limited (indoor only, flat surfaces)
Visual quality	High gloss and depth of colour	Becomes cloudy and matte over time
Price	Higher (Premium quality)	Lower (Budget solution)

How to recognise which resin you have in your hand?

If you have received samples of different types of doming sticker production from a supplier and you are not sure which technology was used, you can perform two simple tests:

1. The Fingernail Test (Shape Memory): Firmly press your fingernail into the centre of the lens. If the mark disappears within a dozen or so seconds – you are dealing with high-quality polyurethane. If the mark remains permanently or the material is so hard that it cannot be pressed into – it is epoxy.
2. The Flexibility Test: Try to gently bend the sticker (while it is still on the backing paper). Polyurethane will bend smoothly like rubber. Epoxy will resist, and with a stronger bend, it may “snap” or crack.

Are resins harmful and how to use them safely?

Many myths have grown around resins. The key to understanding their impact on health is to distinguish between two states: the liquid production mixture and the fully cured, finished product.

Raw Material Safety: Epoxy vs Polyurethane

Epoxy resins: Often contain bisphenol A (BPA), which is a substance that raises health controversies. In their liquid state, epoxies can strongly sensitise the skin and respiratory tract, which is why they require the rigorous use of personal protective equipment.

Polyurethane resins: Professional systems (especially aliphatic ones) are designed to be completely inert to health once cured. In the liquid phase, the key challenge is isocyanates – inhaling them without proper ventilation can be harmful, which is why the pouring process should be automated or take place using protective masks.

Certification and standards (RoHS and REACH)

When choosing a supplier of stickers or raw materials, you should pay attention to compliance with European directives:

REACH: Guarantees that the chemical substances used in production have been registered and assessed for safety for humans and the environment.

RoHS: Confirms that the product does not contain hazardous substances such as lead, mercury, or cadmium. This is particularly important if 3D stickers are placed on toys, medical equipment, or electronics.

Safe working principles (Health and Safety)

For production to be safe, three golden rules must be followed:

1. Ventilation: Constant air exchange in the pouring and drying zone (removal of VOC vapours – volatile organic compounds).
2. Personal protection: Using nitrile gloves (latex allows some resin components to pass through) and safety goggles.
3. Material Safety Data Sheets (MSDS): Every employee should have access to the technical documentation of the chemicals used to know how to react in case of accidental skin contact.

Ecology: Durability as a form of environmental protection

Although resins are plastics, their ecological aspect is manifested in their durability. An epoxy sticker that turns yellow after six months becomes waste. A high-quality polyurethane label that survives 10 years on a product eliminates the need for re-branding and redundant production.

Expert advice: Waste disposal

Liquid resin is hazardous waste and should never enter the sewage system. However, fully cured “leftovers” or defective polyurethane stickers are chemically stable and can be disposed of as standard plastic waste.e, eliminuje potrzebę ponownego znakowania i nadmiarowej produkcji.

Which UV resin is best for 3D doming stickers?

The choice between polyurethane and epoxy comes down to the balance between immediate savings and long-term brand prestige. Although epoxy production is tempting due to its low initial cost, its tendency to quickly yellow and crack makes it a purely temporary solution, intended for products with a short life cycle.

On the other hand, professional polyurethane doming guarantees crystal clarity and “shape memory” for years, effectively protecting the company logo against the sun or mechanical damage. Ultimately, investing in polyurethane resin layer technology turns out to be the most economical choice, as it eliminates the risk of costly complaints and builds customer trust in the quality of the offered product.

The choice depends on what value you want to deliver to your customers:

• Choose epoxy if you are running a low-budget, short-term campaign and price is the only deciding criterion. However, you must expect that after a few months, the domed stickers may lose their aesthetic appearance.
• Choose polyurethane if your logo is to represent the quality of your products for years. It is the only safe choice for professional branding that builds brand trust.

Expert tip: At POLINAL, we only use certified polyurethane resins. We know that the cost of replacing damaged, yellowed stickers at the end customer’s site many times exceeds the savings made on cheaper epoxy.

FAQ about Doming Resins

• What are the common problems encountered during the doming process and how can they be prevented or fixed?

  Air bubbles and “fish eyes” are among the most frequent issues, often caused by improper mixing or contaminants like dust and oil on the substrate. To prevent bubbles, the resin should be degassed in a vacuum chamber before application, and any surface bubbles can often be removed with a quick pass of a flame or heat gun.
  Fish eyes occur when the resin recedes from certain spots due to surface tension issues, which can be avoided by ensuring the printing material is entirely clean and dry. Environmental control is also vital, as high humidity can cause polyurethane resins to become cloudy or develop a foamy texture during curing. Consistent temperature and a dust-free environment are the most effective ways to ensure a flawless, crystal-clear finish.

• What are the safety concerns and best practices for handling and disposing of epoxy and polyurethane resins?

  Handling resins requires strict adherence to safety protocols because these chemicals can cause skin irritation or respiratory issues if handled improperly. It is essential to work in a well-ventilated area and wear appropriate personal protective equipment, including gloves, safety goggles, and respiratory masks when necessary. For disposal, liquid resin and hardener must never be poured down the drain as they are hazardous to the environment and water systems. Best practice involves mixing leftover components to cure them into a solid, inert state before disposal according to local chemical waste regulations. Furthermore, many high-quality polyurethanes are now formulated to be mercury-free to minimise toxic risks during the manufacturing process.

• What are the advantages of using resin domed stickers and labels?

  Resin domed stickers offer an exceptional 3D appearance that significantly enhances the visual appeal and perceived value of a brand’s logo. The clear resin layer creates a magnifying effect that makes colours appear more vibrant and gives the graphics a high-end, professional finish.
  Beyond aesthetics, the dome provides a robust physical barrier that protects the print from scratches, chemicals, and harsh weather conditions. Their inherent flexibility also allows them to be applied to slightly curved surfaces where rigid labels might fail. Ultimately, these labels are highly durable and maintain their glossy, premium look for many years, making them a cost-effective branding solution.