Forming the base
Organic lenses use casting or injection moulding, depending on the polymer. Mineral glass follows its own forming and finishing route. The base defines geometry, weight and optical properties.
SUN LENSES · BEFORE THE FINAL SHAPE
A better view begins
before the frame.
Our focus is the lens. Its material, colour, surface and the way it transmits light. BAHN d.d. is a family business in Trzin, Slovenia, focused on manufacturing lenses for sunglasses.
Explore the technology↗Concept visualisation of uncut sun lenses
BAHN / 01UNCUT SUN LENSES✳MATERIALS & SURFACES✳TRZIN, SLOVENIA
01 / IT STARTS WITH LIGHT
A small element.
A world of technology.
Before a lens takes the shape of a frame, it acquires its essential properties. Material, geometry, filtration and surface treatments shape its future application.
An uncut lens is usually a circular optical element awaiting edging and mounting. It is not necessarily the same as a semi-finished prescription blank that still needs optical surfacing. Our overview focuses on non-prescription sun lenses.
This technology guide describes industry options. Availability of each material, process and specification at BAHN is confirmed upon enquiry.
02 / FROM MATERIAL TO LENS
Technology in every layer.
The production route depends on the material and product requirements. Not every process suits every combination.
Colour and filtration
Solid tints, gradients and absorptive additives influence visible light. UV filtration is a separate property: a darker tint alone does not establish stronger UV protection.
Functional layers
Polarising elements reduce selected reflections. Hard coats, anti-reflective, mirror and finishing treatments complement the base where technically compatible.
Inspection before edging
Optical quality, spectral transmission, surface condition, dimensions and batch consistency matter. Final edging follows the chosen frame geometry.
IN FOCUS / POLARISED SUN LENSES
Less glare.
More visual comfort.
Polarisation adds a distinct function to a sun lens: reducing glare from selected reflections. Performance starts with the lens structure, before it is edged to fit a frame.
A polarising element selectively transmits light according to its direction of oscillation. Its orientation and integration with the lens material are essential to the final optical result.
Precision in every layer
Material compatibility, alignment and coating quality must be considered together.
Quality that can be checked
A useful specification defines transmission, polarisation performance, colour consistency and surface quality.
Polarisation and UV protection are different properties. Compatibility with displays and intended use should be checked for the selected lens. Contact BAHN to discuss available specifications.
Discuss polarised lenses ↗03 / MATERIALS
The right foundation.
For the right purpose.
Selection balances optical quality, weight, durability, geometry and treatment compatibility.
CR-39
An established optical polymer, generally formed by casting. It supports a range of tints and surface treatments.
Optical quality · tinting
Polycarbonate
A lightweight material with high impact resistance. Production requires control of internal stress and surface quality.
Low weight · resistance
Polyamide
A thermoplastic sun lens base combining low weight, design flexibility and treatment options.
Lightness · geometry
Mineral glass
Optical glass with characteristic surface hardness. Selection must consider its higher weight, breakage behaviour and safety requirements.
Optics · surface hardness
04 / COLOUR & FUNCTION
Light, with your signature.
Explore the appearance of tint families. This is a design simulation, not a transmission measurement or an available-product catalogue.
Smoke grey
A neutral visual direction with a restrained, contemporary character.
BAHN / COLOUR STUDY
Polarisation
Reduces glare from selected reflections off roads, water and other surfaces. Polarisation is not the same as UV protection.
Photochromic response
Variable tint depending on activation conditions. Response depends on technology, temperature and light; behaviour behind a windscreen may differ.
Hard coat
Improves surface scratch resistance. Coated lenses still require appropriate cleaning and handling.
Anti-reflective & mirror
Anti-reflective treatment reduces reflections at the treated surface. Mirror coatings create a different reflective and aesthetic effect.
Hydrophobic treatment
A finishing layer that reduces surface wetting by water and can make cleaning easier.
Oleophobic treatment
A surface treatment that helps remove oily marks. Performance and durability depend on the coating system.
05 / QUALITY & STANDARDS
Properties are measured.
Never assumed.
Verifiable specifications matter in the eyewear industry. A lens blank and finished sunglasses are different product stages: final conformity must take intended use and construction into account.
ISO 12312-1
Requirements for sunglasses for general use. The baseline is the 2022 edition with Amd 1:2026. The applicable European version and harmonisation status also need to be considered.
ISO 12311:2023
Reference test methods for determining properties of sunglasses and related eyewear.
Regulation (EU) 2016/425
The European framework for personal protective equipment. Final products require appropriate conformity assessment, documentation, labelling and instructions.
References to standards are informational and do not claim certification of BAHN or any individual product.
06 / A FAMILY BUSINESS
From Trzin.
With a personal signature.
BAHN d.d. is a family business in Trzin, with a story that continues from one generation to the next. Katarina Bahn took over the company from her father and expanded its production capacity. Sunglass lenses and expertise in materials, light and precision manufacturing remain at its heart.
The year 2026 opens a new chapter: BAHN is exploring new directions and planning a merger with GLAZEX. This marks a new stage in the development of the family business. Contact us directly to discuss cooperation and future opportunities.
Katarina BahnFamily business successor
07 / FINAL APPLICATION
The lens gives
eyewear its character.
The frame defines the silhouette. The lens adds colour, reflection and optical function. This design study illustrates one possible aesthetic direction for sun lens applications.
AI design study. Not a product offered for sale.GOOD TO KNOW
Answers before the first sample.
Does “glass” always mean mineral glass?
No. In everyday optical terminology, the word can also refer to organic polymer lenses. A technical enquiry should always identify the actual material.
Is an uncut lens ready to mount?
Its edge needs to be shaped to the frame before mounting. Further processing and checks depend on the supplied production stage and final construction.
Do darker lenses offer more UV protection?
No. Visible-light attenuation and UV filtration are different properties. They are established through data and testing, not appearance.
What does UV400 mean?
The term refers to filtering UV radiation up to the 400 nm region. Specific claims require appropriate measurement; the label alone does not replace conformity evidence.
Can all technologies be combined?
No. Compatibility between the substrate, polarisation, tint and coatings must be checked for the specific design.
What should an enquiry include?
Intended use, preferred material, diameter, base curve, colour, filtration, coatings, estimated quantity and target market. If you do not have a specification yet, describe your project.
LET’S START WITH YOUR IDEA
A conversation about
your next perspective.
Developing a collection or exploring sun lens options? Send us your initial requirements and ideas.
info@bahn.si ↗Technical references
Industry technology and standards overview, checked October 2026. Links do not imply a business partnership.
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