Ahh, so you’re delving down the rabbit hole of sun lens materials huh?
Choosing the right one for your shades can be crucial for comfort, protection, visual clarity and lifestyle.
Among the (many) lens materials available, TAC and polycarbonate lenses definitely stand out as two of the most common.
To help you make a more informed decision, this blog post helps you explore the differences and benefits of these two popular lens types.
Let’s dive in.
What is the difference between TAC and polycarbonate lenses?
TAC sunglasses lenses are made using multiple layers of material (cellulose) sandwiched together which are lightweight and very affordable. Meanwhile, polycarbonate lenses are made from a single piece of material (thermoplastic) which are known to be highly impact-resistant but more expensive.
For a greater understanding, let’s take a closer look at each of these lens types in more detail.
What are TAC Lenses?
TAC lenses, or Tri Acetate Cellulose lenses, are made from one of the world’s most naturally abundant compounds (cellulose) which can be found in 33% of all plant matter. Interestingly, this material can be used to make both your frame and optical lenses.
Acetate is known for its superior optical clarity and lightweight nature which is why these lenses are commonly used in sunglasses and sports eyewear.
TAC lenses are constructed of multiple layers, often including a polarised layer, which helps reduce glare from reflective surfaces such as water, snow or wet roads etc. Combined together, these layers work in unison for great optical performance.
TAC lenses are typically made in uneven layers, varying from 3,5,7 or even 9 layers, depending on the supplier/brand. 7 or 9 layers tends to be the most common, which include;
- Anti-scratch film #1
- Anti-reflective coating
- UV protective film #1
- Anti-distortion layer #1
- Polariser film
- Anti-distortion layer #2
- UV protective film #2
- Strength layer
- Anti-scratch film #1
Advantages of TAC Lenses
Superior Optical Clarity: TAC lenses provide excellent visual clarity, making them ideal for general use, right through to activities requiring precise vision.
Lightweight: Due the low density and lightweight characteristics of acetate, TAC lenses help to reduce the weight of your sunglasses, making them comfortable to wear for extended periods.
Affordability: Acetate is cheaper to manufacture than polycarbonate, therefore TAC lenses are a more budget-friendly lens material.
Polarised: TAC lenses typically contain a polariser layer within the lens ‘sandwich’ which is used to diminish harsh reflections known as glare. Over long durations of exposure, the alleviation of glare helps prevents visual fatigue whilst improving visual clarity.
Limitations of TAC Lenses
When compared to polycarbonate, the main drawbacks of TAC lenses is lower impact resistance and inability to be made to your prescription.
Polycarbonate is simply more resilient to knocks, drops and bumps which is why TAC lenses are less suitable for sport. That being said, TAC lenses are by no means prone to shattering, but they just simply aren’t as robust as polycarbonate, which for sport, may be an issue.
Furthermore, TAC lenses cannot be made to your prescription which means they’re only suitable for non-prescription sunglasses.
If you play field sports such as hockey or soccer and need corrective sun lenses, TAC lenses aren’t they way to go here.
Now, let’s take a closer look at polycarbonate lenses.
What are Polycarbonate Lenses?
Polycarbonate lenses are made thermoplastic polymers which are injection moulded into single-piece ‘lens blanks’. These lenses are flexible, tough and hugely impact resistant.
Invented in the 1950’s, polycarbonate lenses prove to be more than 200 times stronger than mineral glass lenses with a high refractive index. This makes them a superior choice for safety glasses, children’s eyewear, and sports goggles.
In fact, polycarbonate is so strong, it’s the same material used to make bullet-proof windows.
Advantages of Polycarbonate Lenses
High Impact Resistance: These lenses are highly resistant to impacts, making them ideal for safety and sports eyewear.
Built-in UV Protection: Polycarbonate lenses offer built-in UV protection, shielding your eyes from UVA and UVB sunlight. This avoids the need for additional UV coatings which can deteriorate over time.
Prescription ready: If you require optical correction, polycarbonate lenses can be made to your prescription whilst providing visual comfort and UV protected vision.
Lightweight: Like TAC lenses, polycarbonate lenses are also incredibly lightweight, providing comfort for prolonged use.
Thinner: Compared to other lens materials such as CR39, polycarbonate lenses can be as much as 30% thinner, especially in prescription lenses. This is because they have a higher refractive index.
Limitations of Polycarbonate Lenses
Prone to Scratching: While durable, polycarbonate lenses can be more susceptible to scratching if not coated with an additional scratch-resistant layer.
Optical Clarity: The optical clarity of polycarbonate lenses may be slightly less than that of TAC lenses. This is because polycarbonate has a lower refractive index than TAC.
7 Key Differences Between TAC and Polycarbonate Lenses
#1 Material Composition and Manufacturing Process
TAC lenses are made from multiple layers of Tri Acetate Cellulose, while polycarbonate lenses are made from a single layer of polycarbonate plastic.
#2 Optical Clarity and Visual Performance
TAC lenses offer superior optical clarity, making them ideal for precision tasks. Polycarbonate lenses, while clear, may not quite match the optical clarity of TAC lenses.
#3 Impact Resistance and Durability
Polycarbonate lenses excel in impact resistance, making them suitable for high-risk environments. TAC lenses, though durable, do not offer the same level of impact protection.
#4 UV Protection and Coatings
Both lens types provide UV protection, but polycarbonate lenses typically have built-in UV protection, whereas TAC lenses may require an additional coating.
#5 Weight and Comfort
Both TAC and polycarbonate lenses are lightweight, ensuring comfort during extended wear.
#6 Price Comparison
TAC lenses are generally more affordable than polycarbonate lenses, making them a cost-effective choice for many users.
#7 Prescription-ability
TAC lenses cannot be made as prescription sun lenses, whilst polycarbonate lenses can.
Choosing the Right Lens for Your Needs
When deciding between TAC and polycarbonate lenses, consider your specific needs and preferences.
Everyday Use and Casual Wear: TAC lenses are a great choice for everyday sunglasses due to their optical clarity and affordability.
Sports and Outdoor Activities: For sports and outdoor activities where impact resistance is crucial, polycarbonate lenses are the preferred option.
Safety and Industrial Applications: Polycarbonate lenses are ideal for environments where eye protection is paramount.
Children's Eyewear: Given their durability and safety features, polycarbonate lenses are recommended for children’s eyewear.
Conclusion
As you’ve discovered, choosing between TAC and polycarbonate lenses largely depends on your specific needs and priorities.
TAC lenses offer excellent optical clarity and affordability, making them ideal for everyday use. Polycarbonate lenses provide superior impact resistance and UV protection, making them suitable for high-risk activities, safety lenses and children’s eyewear.
By understanding the differences and benefits of these lenses, you can now hopefully make an informed decision that best suits your lifestyle and needs.
FAQ’s
Are TAC lenses good?
Yes, TAC lenses are good for their superior optical clarity, lightweight nature, and affordability. They are particularly suitable for everyday sunglasses and casual wear.
What is a TAC lens?
A TAC lens, or Tri Acetate Cellulose lens, is made from multiple layers including a polarised layer, providing excellent optical clarity and glare reduction, often used in sunglasses and sports eyewear.
What lenses are better than polycarbonate?
Depending on the need, high-index lenses such as Trivex or crown glass lenses may offer better optical clarity than polycarbonate. However, polycarbonate lenses excel in impact resistance and durability.
What is so special about TAC glasses?
TAC glasses are special due to their superior optical clarity, lightweight design, and polarised layer, which reduces glare, making them ideal for activities requiring precise vision and comfort. Furthermore, they’re also very affordable which makes them popular for non-prescription use.
Are TAC glasses just polarised?
Yes, TAC glasses are typically polarised, which means they reduce glare from reflective surfaces, enhancing visual comfort and clarity, especially in bright conditions. Due to their multi-layered construction, a polariser film is added within the lens to help diminish harsh reflections from water, snow or wet roads.
What is a cheap alternative to polycarbonate?
A cheaper alternative to polycarbonate lenses is acrylic. This entry-level lens material offers reasonable optical clarity, can be polarised and are more affordable. However, they’re less impact-resistant and are prone to peripheral distortion.
Do I really need polycarbonate lenses?
You only really need polycarbonate lenses if you require high impact resistance for sports, safety, or children’s eyewear. For general use such as driving, TAC lenses are more than sufficient.
Do TAC lenses shatter?
TAC lenses are more prone to shattering, chipping and cracking compared to polycarbonate lenses. Of these two lens types, polycarbonate lenses are much better at withstanding high impacts and are virtually shatterproof.
Hopefully, you found this article helpful.
Thanks for stopping by.