Window Tint Guide: Understand
Window Tint Glossary: 40 Terms Explained
Tint quotes, spec sheets and the South Carolina statute all use their own vocabulary, and a lot of it sounds alike. VLT and TSER, IR and UV, AS1 and AS2, dot matrix and frit: if you have ever nodded along at a counter without being sure what a term meant, this page is for you.
The 40 terms below are grouped the way you meet them: the numbers on a spec sheet, how film is built, the glass and the vehicle, the installation, and the legal terms from S.C. Code § 56-5-5015. Each definition is short, and the legal ones follow the statute's own wording.
The short answer
The window tint terms that matter most are VLT, the share of visible light a window lets through; TSER, the share of total solar energy a film blocks; IR rejection, how much infrared heat it stops; and UV rejection. In South Carolina, the legal terms are the 27 percent combined light transmission rule, the AS1 line on the windshield, the MPV rear-window exception and the certificate of compliance.
Key points
- VLT is visible light transmission, and lower numbers mean darker windows.
- Combined VLT is what matters legally in South Carolina: film and factory glass measured together.
- TSER describes total heat blocked; an infrared figure at a single wavelength is not the same thing.
- The AS1 line is a marking on the windshield, and South Carolina keeps film above it.
- Every tinted window in South Carolina needs a certificate of compliance under the film.
The numbers
Spec Sheet Terms
- VLT (visible light transmission)
- The percentage of visible light that passes through a film or window. Higher numbers are lighter: the International Window Film Association notes that a 70 percent film is nearly clear, while a 15 percent film looks nearly black from outside. VLT explained
- Combined VLT
- The light transmission of film and glass together, roughly the two percentages multiplied. South Carolina's 27 percent rule uses this combined figure, not the film's rating. The 27% math
- Light transmissionstatutory term
- South Carolina's statute defines it as the ratio of the total visible light that passes through a product to the total light falling on it. In practice, it is the same idea as VLT.
- TSER (total solar energy rejected)
- The share of the sun's total energy, visible, infrared and ultraviolet together, that a film keeps from passing through. It is the most useful single number for comparing heat performance. Reading a spec sheet
- IR rejection
- How much infrared light, the part of sunlight you feel as heat, a film blocks. Be careful: a figure measured at one infrared wavelength can look much higher than the film's overall heat rejection.
- UV rejection
- The share of ultraviolet light a film blocks. LLumar rates its automotive films to block up to 99 percent of UV rays, attributed to the manufacturer.
- Luminous reflectancestatutory term
- The share of light a film reflects back outward. South Carolina's statute defines it but sets no numeric limit; instead it requires film to be nonreflective.
Construction
How Film Is Built
- Polyester base
- The clear, thin plastic sheet that carries the color, heat-control layers and adhesive. Most automotive films are built on polyester.
- Dyed film
- Film colored with dye. It is affordable and looks good new, but dye can break down in strong sun over time, which is how old film turns purple. Why tint turns purple
- Carbon film
- Film that gets its charcoal color from carbon built into the film rather than surface dye, so the shade stays true instead of fading or turning purple. It has no metal layer.
- Ceramic (nano-ceramic) film
- Film embedded with microscopic nano-ceramic particles that block infrared heat. LLumar says all ceramic tint rejects the sun's most heat-causing infrared rays, so it can keep a cabin cooler without the darkest shade.
- Infrared (IR) tint
- A marketing name. LLumar says newer ceramic films with more concentrated nano-ceramic particles are sometimes called infrared tint or IR-blocking film. Ask for the spec sheet rather than relying on the name. Ceramic vs infrared
- Metallized film
- Film with a layer of tiny metal particles that reflect heat and give the glass a slight sheen. Metal can weaken radio signals such as GPS and toll tags. Tint and electronics
- Clear film
- Nearly clear film made to block UV or heat with little change in darkness. In South Carolina it is still a sunscreening device, so windshield placement rules apply to it too.
- Adhesive
- The layer that bonds the film to the inside of the glass. It is activated and positioned with slip solution, then dries and grips harder over the curing period.
- Scratch-resistant coating
- The hard top layer on the film's exposed side. It resists everyday wiping, but seat belts, rings, pet claws and ice scrapers can still mark it.
Glass and vehicle
Terms About the Car Itself
- AS1 line
- A marking the glass maker prints near the top of the windshield under the federal glazing standard. Below the shade band, windshield glass must pass at least 70 percent of light. South Carolina allows film only above the AS1 line. The AS1 line rule
- Shade band
- The top band of a windshield that may be tinted from the factory and is excluded from the federal 70 percent light requirement. Its lower edge is marked by the AS1 line.
- Dot matrix (frit)
- The black ceramic band and fading dot pattern printed around the edges of many windows, especially back glass. Film does not lie perfectly flat over the dots, so edges there can look slightly silvery or hazy. Gaps and edges
- Factory privacy glass
- Glass darkened during manufacturing, common behind the driver on SUVs and pickups. It is not a tint violation by itself in South Carolina, but film added over it is measured together with it. Privacy glass vs tint
- Safety glazing
- Automotive glass built to federal Standard No. 205, which incorporates the ANSI/SAE Z26.1 standard. Its markings, such as AS1, identify the glass type and where it may be used.
- Defroster grid
- The thin heating lines on the rear window. Film can go over them, but careless removal of old film can damage them. Tint and defroster lines
- Rear-most windowstatutory term
- South Carolina's term for the back glass. Film there must be nonreflective and 27 percent combined, except on MPVs, and the car needs both outside mirrors if it is filmed.
- MPV (multipurpose passenger vehicle)statutory term
- A vehicle for ten people or fewer built on a truck chassis or with features for occasional off-road use. In South Carolina, the light limit does not apply behind the driver on an MPV. SUVs, vans and pickups
- Certification label
- The federal label on the driver's door edge or pillar. It lists the vehicle's type classification, such as MPV or truck, which decides whether the rear-window exception applies.
Installation
Terms You Hear in the Bay
- Computer cut
- Film cut by a plotter from a pattern for your specific vehicle, rather than trimmed freehand with a blade on the glass. How tint is installed
- Heat shrinking (heat forming)
- Using a heat gun to shrink film so it follows the curve of the glass, mostly on back windows, before it is applied.
- Slip solution
- A soapy water mix sprayed on the glass and adhesive so the film can be slid into position before it is squeegeed in place.
- Squeegee
- The hard-edged tool used to push water and air out from under the film and set the adhesive against the glass.
- Micro-edge
- A film edge filed or trimmed so it stops just short of the glass edge on roll-down windows, leaving a thin, even line that will not catch when the window moves.
- Light gap
- The thin strip of untinted glass at the top or edges of a window where the film stops. Small, even gaps are normal; wide or wavy ones point to trimming problems.
- Curing
- The days after installation while leftover moisture evaporates and the adhesive grips fully. Windows stay up and untouched for the period the installer gives. Curing time
- Haze
- A cloudy or milky look from moisture still trapped under new film. It usually clears as the film cures; haze that lasts beyond the cure period is worth reporting.
- Contamination
- Dust, hair or fibers trapped between film and glass, seen as small specks or bumps. A clean bay and careful prep keep it to a minimum. Specks under tint
The law
South Carolina Legal Terms
- Sunscreening device
- The statute's word for window film: a film material or device designed to be used with the car's safety glass to reduce the effects of the sun. It covers dark and clear films alike. SC tint law guide
- Nonreflective
- Defined by statute as a product primarily designed to absorb light rather than reflect it. All film in South Carolina must be nonreflective, and it may not be red, yellow or amber.
- Certificate of compliance
- The small sticker, no larger than 2 inches square, sealed between film and glass on each tinted window. It shows the film's percentage, the installer's name, address and phone, and the install date. Certificate guide
- Professional window tinter
- The statute's term for a person who installs film for profit. Tinters who skip certificates face a fine of at least $1,000 or up to 30 days, or both, per offense.
- Medical affidavit
- A sworn statement from a South Carolina licensed physician or optometrist that a person's condition makes darker or more reflective film necessary. It must stay in the car and be updated every two years. Medical exemption
- Tint meter
- A handheld device that reads how much light passes through a window. The statute does not require any particular device, and the Attorney General has said meters are not excluded as evidence. How meters work
Have a term we did not cover?
Ask us. We install LLumar Carbon and LLumar Ceramic, computer cut for your vehicle, check the legal shade before installing, and label every tinted window with the state certificate.
Common questions
What is the difference between VLT and tint percentage?
They are usually the same number. When people say 35 percent tint, they mean film with about 35 percent visible light transmission. The catch is that the film's percentage is not what ends up on the window: glass absorbs some light too, so the combined reading is darker than the film's rating.
Is a higher or lower tint percentage darker?
Lower is darker. The percentage is how much visible light gets through, so 20 percent lets through less light than 50 percent. The International Window Film Association describes a 70 percent film as nearly clear and a 15 percent film as looking nearly black from outside.
What does TSER mean on a window film spec sheet?
Total solar energy rejected: the share of the sun's total energy, visible light, infrared and ultraviolet together, that the film keeps out. It is a better guide to how much cooler a car will feel than an infrared figure measured at a single wavelength, which can look impressive while saying little about overall heat.
What is the black dotted border on my back window?
That is the ceramic frit, often called the dot matrix: a black band and fading dot pattern printed around the glass edge. Film cannot press perfectly flat over the raised dots, so the edge there may look slightly silvery or hazy after tinting. That is normal and does not mean the film is failing.
Sources
- S.C. Code Ann. § 56-5-5015, South Carolina Legislature (https://www.scstatehouse.gov/code/t56c005.php), accessed October 2026
- S.C. Code Regs. 38-621, Installer to Apply Non-Transferrable Approval Certificate, Chapter 38 Department of Public Safety, South Carolina Legislature (https://www.scstatehouse.gov/coderegs/Chapter%2038.pdf), accessed October 2026
- Automotive Window Film and Your Car, International Window Film Association (https://iwfa.com/automotive/), accessed October 2026
- Ceramic Window Tint, LLumar / Eastman Performance Films (https://llumar.com/en/tint/ceramic/), accessed October 2026
- Control Heat and Protect Your Ride with Metallized Tint, LLumar / Eastman Performance Films (https://llumar.com/en/tint/metallized/), accessed October 2026
- 49 CFR 571.205, Standard No. 205, Glazing materials, eCFR (https://www.ecfr.gov/current/title-49/subtitle-B/chapter-V/part-571/subpart-B/section-571.205), accessed October 2026
- Federal Motor Vehicle Safety Standards; Glazing Materials, Notice of Proposed Rulemaking, 77 FR 37478 (June 21, 2012), NHTSA via Federal Register (https://www.federalregister.gov/documents/2012/06/21/2012-14996/federal-motor-vehicle-safety-standards-glazing-materials), accessed October 2026
- 49 CFR 567.4, Requirements for manufacturers of motor vehicles, eCFR (https://www.ecfr.gov/current/title-49/subtitle-B/chapter-V/part-567/section-567.4), accessed October 2026
- Opinion to Chief Robert H. Wunderlich on the use of battery-operated tint meters, March 1, 2012, Office of the South Carolina Attorney General (https://www.scag.gov/wp-content/uploads/2012/03/wunderlich-r-h-os-9401-3-1-12-use-of-battery-operated-tint-meters.pdf), accessed October 2026
Prices on this page are The Auto Show’s published starting prices. Film ratings and warranty terms come from the manufacturer. This guide explains South Carolina law in plain words; it is not legal advice.