Density of Polyester Film: Technical Data Sheet

Technical Scope

This polyester film density technical data sheet supports base film weight review, PET film roll weight calculation, GSM calculation, material yield checks, and finished protective film structure review. It applies to clear PET film, BOPET film, adhesive protective film, coated film, and converted rolls or sheets.

It does not replace product selection, surface protection planning, or full PET film mechanical data. For broader tensile strength, elongation, haze, light transmittance, shrinkage, and surface treatment details, review PET film mechanical and optical data together with this density reference.

Material / Product Structure

A polyester protective film structure usually includes a PET or BOPET base film, an adhesive layer, and optional surface treatment or liner. For substrate selection, compare industrial PET base film options with thickness and surface treatment needs.

For finished adhesive structures, clear adhesive PET film structure helps separate base film weight from adhesive add-on, coating add-on, liner, core, and packaging.

Main Technical Data Sheet

Item	Typical Value / Reference Range	Test Method or Condition	Notes
Base film	PET / BOPET polyester film	Material grade confirmation	For protective, coated, printed, laminated, or converted film
Typical density	1.38-1.40 g/cm3	ASTM D1505, ASTM D792, ISO 1183 series, or equivalent method	1.39 g/cm3 is a common calculation reference
Specific gravity	1.38-1.40 reference range	Laboratory comparison	Close to density value in g/cm3
Unit conversion	1380-1400 kg/m3 / about 0.0499-0.0506 lb/in3	Converted from g/cm3	For metric and inch-based calculation
Base film thickness	12-250 um typical range	Thickness gauge / project-confirmed value	Use actual thickness for GSM and roll weight
Total thickness	Base film + adhesive + coating / liner if used	Micrometer or cross-section check	Do not assume from base film only
GSM calculation	Thickness um x density g/cm3	Calculation reference	50 um PET at 1.39 g/cm3 is about 69.5 g/m2 before coating
Roll weight calculation	Width m x length m x thickness um x density g/cm3 x 0.001	Base film calculation	Add adhesive, liner, core, and packaging separately
Peel adhesion	Project-confirmed value	180-degree peel test	Density does not predict adhesive behavior
Haze / transmittance	Project-confirmed value	Optical meter or visual check	For clear or visible surface protection
Storage condition	Cool, dry, shaded storage	Warehouse observation	Heat, humidity, sunlight, and compression may affect use result

Test Methods and Conditions

Test Item	What It Checks	Suggested Method or Reference	Why It Matters	When To Request It
Density / specific gravity	Mass per volume of base film	ASTM D1505, ASTM D792, ISO 1183 series, or equivalent method	Supports GSM, yield, and roll weight	When grade or calculated weight must be verified
Thickness / GSM	Base film and finished structure weight	Thickness gauge plus cut and weigh film GSM check	Finds tolerance or coating add-on	When roll weight differs from calculation
Peel adhesion	Adhesive force on defined surface	180-degree peel test, FINAT / ASTM / internal method	Reviews hold, removability, and residue risk	Before use on glass, metal, plastic, painted, or coated surfaces
Tensile / elongation	Pull strength and stretch behavior	MD / TD tensile test	Affects handling, die-cutting, and removal	When film passes rollers, cutters, or transport handling
Haze / transmittance	Clarity and visual inspection quality	Optical meter or controlled visual check	Important for transparent protection	When used on visible surfaces
Residue / edge lift	Adhesive trace and edge stability	24h / 72h / 7 days sample peel test	Checks clean removal risk control	Before full use on sensitive or coated surfaces

How To Read These Technical Values

A correct density value supports polyester film GSM calculation, PET film roll weight calculation, and material yield review, but it does not confirm peel adhesion, holding force, haze, or surface compatibility. The same density can produce different finished roll weights when adhesive, coating, liner, or core weight changes. Thickness tolerance can also change GSM, stiffness, edge contact, cutting behavior, and calculated roll weight.

Application Compatibility Notes

For glass, check haze, bubbles, edge lifting, adhesive trace, and surface shadow. For metal, review oil, polishing compound, coating condition, forming pressure, and transport distance. For plastic, confirm surface energy because PVC, acrylic, PC, ABS, PP, and PE may behave differently. Painted, coated, rough, or low energy surfaces need sample peel testing because results depend on surface type, temperature, humidity, sunlight, storage time, equipment setting, and operator method.

Sample Testing Before Full Use

Use the same surface, cargo shape, load weight, storage condition, transport distance, equipment setting, and operator method expected in actual use. For glass surfaces, glass protection sample testing helps verify peel behavior, bubbles, edge lifting, adhesive trace, surface shadow, and gloss change under actual dwell conditions.

Check 24h, 72h, and 7 days peel behavior, edge lifting, adhesive trace, surface shadow, gloss change, bubbles, film tearing, and residue observation. Trial run is recommended before automated application.

Common Data Mismatch and Failure Risk

When calculated roll weight and actual roll weight do not match, coating, slitting, and roll quality controls can help review adhesive add-on, thickness tolerance, winding tension, core weight, and converting settings.

Data Point	If Too Low	If Too High	Risk in Application	Check Before Full Use
Density reference	Underestimated roll weight	Overestimated roll weight	Wrong GSM, yield, or material planning	Use tested grade or project-confirmed value
Base film thickness	Wrinkle, tear, weak handling	Stiff film, poor conformity	Edge lift or difficult removal	Confirm thickness tolerance
Adhesive coat weight	Low holding force	Higher residue risk	Surface exposure or adhesive trace	Run peel test on actual surface
Peel adhesion	Edge lifting	Hard removal on sensitive surface	Residue, mark, or coating pull risk	24h / 72h / 7 days dwell check
Tensile / elongation	Film break or split	Distortion or poor fit	Tearing, wrinkles, poor alignment	MD / TD tensile test and removal trial
Storage condition	Low tack or poor unwind	Blocking or compression marks	Adhesion shift or edge marks	Check storage date, carton, humidity, and roll pressure

Storage and Handling Notes

Polyester base film density is stable, but finished protective film behavior can change after heat, humidity, sunlight exposure, long storage time, heavy stacking pressure, packaging damage, or long transport distance. Store rolls in a clean, dry, shaded area. Record packaging damage or moisture exposure before testing.

FAQ

What is the typical density of polyester film?

The density of polyester film is commonly referenced at 1.38-1.40 g/cm3 for PET / BOPET base film. A value near 1.39 g/cm3 is often used for GSM and roll weight calculation, but exact material weight should use project-confirmed data.

How do you calculate GSM from polyester film density and thickness?

GSM can be estimated as thickness um x density g/cm3. For example, 50 um PET film at 1.39 g/cm3 is about 69.5 g/m2 before adhesive, coating, liner, core, or packaging weight.

Why can calculated roll weight differ from actual roll weight?

Common reasons include thickness tolerance, adhesive add-on, coating add-on, liner weight, core weight, roll width tolerance, scale method, and incorrect density reference. Finished roll weight should be checked by actual weighing when accuracy matters.

Does density confirm peel adhesion or residue behavior?

No. Density helps calculate base film weight. Peel adhesion, edge lifting, residue observation, haze, gloss change, and surface compatibility require sample peel testing under expected surface, temperature, humidity, storage, transport, and equipment conditions.