Available film constructions
For all six number-balloon sizes, buyers can choose Nylon + PE composite film at 0.028 mm, or PET + PE composite film at 0.029, 0.027 or 0.024 mm. UNDALO does not recommend using film below 0.027 mm. The 0.024 mm PET option is available but not recommended.
Material and thickness are separate specification fields. A material name does not describe every layer or establish every aspect of finished-balloon performance.
How the confirmed indoor performance differs
Under normal indoor use, the stated continuous helium-floating period is 5 days for PET and 7 days for Nylon before the balloons gradually become less full and develop wrinkles. They may continue floating for approximately 2 further days with reduced fullness.
When filled with air, both materials can remain inflated for 15 days or more. These are UNDALO-provided figures for this number-balloon range, not a universal comparison of every nylon and PET balloon.
Choose material and inflation method together
All six sizes can be air filled. The 36, 38 and 40 inch sizes are recommended for helium floating; the 16, 18 and 32 inch sizes are not recommended. This size guidance applies to both confirmed materials. Selecting Nylon does not change the guidance for the smaller sizes.
What this comparison does not establish
The outer Nylon or PET film provides strength and toughness. The laminated inner PE film provides heat-sealability and helps create a sealed balloon. Use the supplier specification and relevant test data when comparing individual layers and mechanical strength.
Frequently asked questions
Can all six sizes use either material?
Yes. Each of the six sizes supports Nylon + PE at 0.028 mm or PET + PE at 0.029, 0.027 or 0.024 mm, as selected by the customer. Film below 0.027 mm is not recommended.
Does Nylon have a longer stated floating period?
For this UNDALO number-balloon range under normal indoor use, Nylon is stated at 7 days and PET at 5 days before gradual loss of fullness. Both may continue floating for about 2 more days with wrinkles.
Does Nylon make the smaller sizes recommended for helium?
No. The confirmed guidance still recommends helium floating for 36, 38 and 40 inch sizes, and not for 16, 18 and 32 inch sizes.