Custom Plastic Skincare Bottle Manufacturers

How to ensure the sealing of the mouth design of plastic skincare bottle

In the increasingly fierce competition in the skincare industry, packaging is not only the external expression of brand image, but also the key factor to ensure product quality and user experience. Among them, the mouth design of plastic skincare bottle plays a vital role. The sealing of the mouth is directly related to the product's leak-proof, anti-oxidation, quality preservation and hygienic use.
The core principle of sealing design
The sealing design of plastic skincare bottle is usually based on the combination of the following methods:
Precise matching screw threading design
The screw threading made by precision injection molding can perfectly bite with the pump head or cap to form a stable physical sealing structure. Roman Plastic uses high-precision molds and German imported injection molding equipment to ensure that the tolerance between the bottle mouth and the cap is controlled at the micron level, thereby avoiding leakage during transportation or daily use.
Soft gasket/seal ring (Gasket or Liner) embedding
Adding a layer of flexible sealing material such as EPE, EVA or silicone gasket inside the bottle cap can automatically form an airtight barrier when the bottle mouth is closed. Shaoxing Roman Plastic has 15 automated production lines in the assembly process to ensure that each bottle cap can be accurately embedded in the gasket to improve product consistency.
Airless Pump Design
For high-end skin care products, such as essences or active ingredient skin care products, Roman Plastic provides vacuum bottle solutions. Its bottle mouth has a ventless structure, which effectively blocks air, avoids oxidation and secondary contamination, and ensures that a constant dose output is maintained with each press.
Snap-on & Lock System
In some portable products or travel packaging designs, the snap-on lid design is used, combined with a concave-convex structure locking mechanism, which effectively prevents accidental opening and improves the safety of out-of-town use. The product design team of Roman Plastic has made a good balance between the strength of the bottle mouth lock and the convenience of opening.
Process and testing: Sealing guarantee mechanism
Shaoxing Roman Plastic Co., Ltd. was founded in 2016 and is located in Shangyu City, Zhejiang Province, China. It has a superior geographical location and is close to Ningbo and Shanghai ports. It covers an area of ​​13,000 square meters, has more than 100 employees and more than 50 injection molding equipment. Since its establishment, the company has always adhered to the operating concept of **"integration of design, manufacturing and testing"**, and pays special attention to the comprehensive control of product sealing performance.
During the production process, Roman Plastic strictly implements ISO standards and conducts the following tests on the sealing of the bottle mouth:
Leakage Test: Through vacuum testing, inverted pressurization and other methods, simulate various states of the product during transportation to ensure that the bottle mouth is leak-free.
Open/close fatigue test: Repeatedly open and close more than 1,000 times to test whether the bottle mouth lock structure is loose and verify the product life.
Constant temperature sealing test: Test the sealing under high temperature, high humidity and low temperature environments to adapt to the climatic conditions of different markets (such as the Middle East or Europe).
Tailor-made sealing solutions for customers
Roman Plastic not only provides standard bottle types, but also accepts OEM/ODM customized services. In the early stages of the project, the company's engineering team will communicate with customers in depth about the characteristics of the contents (whether it is easy to oxidize, whether it contains acid and alkali, etc.), and tailor the bottle mouth structure and sealing design according to the texture, viscosity, volatility and other indicators of the skin care products.
For example, for essences containing active vitamin C, Roman Plastic recommends the use of a triple structure combination of UV blocking bottle + vacuum pump + silicone sealing pad to greatly extend the product stability and shelf life.

What are the surface treatment methods of plastic skincare bottles

Spraying
Spraying is the most common surface treatment method, which is to spray liquid paint evenly on the surface of the bottle to form the desired color, matte or pearlescent effect. Roman Plastic has an efficient spraying process line that can achieve a variety of effects such as single color, two-color, gradient color according to customer needs, and can be applied to common plastic substrates such as PET and PP.
Spraying is suitable for products that need to change the color of the bottle over a large area, especially in the skin care market. It can convey the brand's main color and product positioning (such as high-end black gold, mild milky white, natural green, etc.), and enhance the user's first visual impression.
UV Coating
UV coating (ultraviolet light curing coating) is a transparent or colored high-gloss coating that is instantly cured by ultraviolet light to form a hard and smooth surface. This process not only gives the bottle a strong mirror texture, but also has the characteristics of scratch resistance, alcohol resistance, and strong weather resistance.
Roman Plastic has accumulated a lot of engineering practice experience in the field of UV coating, which is often used for the outer shell treatment of mid-to-high-end essence bottles or cream jars, helping brands achieve a "glass feel" or "porcelain glaze feel" packaging vision. The UV surface can also provide a protective barrier to prevent packaging aging caused by the interaction between the contents and the air.
Silk Screening
Silk screen printing is currently one of the most widely used printing processes on plastic packaging. The ink is printed on the surface of the bottle through the screen, which can present key information such as LOGO, product name, and instructions for use. Shaoxing Roman Plastic is equipped with multiple high-precision screen printing equipment, which supports multi-color printing and fine line presentation. The graphics are highly wear-resistant and are widely used for the main logo printing of daily chemical products such as facial cleansers and body lotions.
It is particularly worth mentioning that Roman Plastic can provide UV screen printing inks, which greatly improve the color saturation and surface strength of the printed part, and are more suitable for high-end product lines.
Hot Stamping
The hot stamping (or hot silvering) process transfers the metal foil film to the surface of the bottle through high temperature and pressure, forming bright metallic luster graphics or graphics, which are widely used in high-end skin care products and luxury fragrance bottle packaging.
Roman Plastic is good at superimposing hot stamping with multiple processes such as screen printing and UV spraying, such as partially hot stamping the LOGO on the matte spray bottle to create a strong visual contrast and highlight the brand imprint. The company has introduced automated hot stamping equipment, which can realize a variety of positioning methods and fine transfer of complex patterns.
Label Sticking
Labeling is a conventional method for low-volume and variable product lines, especially for customers who need to switch SKUs quickly. Roman Plastic uses an automatic labeling line that can paste various types of labels such as transparent, self-adhesive, and environmentally friendly films, and has local hot stamping and cold transfer functions, allowing customers to create a unique appearance at low cost.
The biggest advantage of labeling is flexibility and speed. At the same time, it supports functional expansion such as anti-counterfeiting labels and QR code stickers, which facilitates product marketing and traceability management.