Kirkland Signature · Microwave Popcorn
Kirkland Signature Microwave Popcorn Movie Theater Butter
Skip; grease-resistant coatings commonly contain PFAS, no disclosure.
Kirkland does not disclose the composition of the grease-resistant coating on this microwave popcorn bag. Grease-resistant food packaging typically contains PFAS-based coatings.
The better-graded swap
Wabash Valley
Wabash Valley Farms Sweet
70/100 safety
Same rubric that flunked this product. The swap earned Good.
Still want this one anyway? Check the price on Amazon. We’d swap it.
Material
paper-based microwave popcorn bag with grease-resistant coating
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
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What Kirkland Signature Theater Butter is made of, ingredients and materials
Kirkland microwave popcorn bags are paper-based with a grease-resistant interior coating designed to contain butter and oil during heating without leaking or soaking through. Grease-resistant coatings on food contact papers commonly rely on PFAS "forever chemicals" (PFAS) to repel fats, though Kirkland does not publicly disclose the coating chemistry. When the bag is heated in a microwave, there is potential for migration of coating residues into the food, particularly the oily popcorn, though the extent depends on coating formulation and bag manufacturing standards.
What’s concerning
Waterproof / stain-resistant treatment
Water-repellent coating treatments have historically used PFAS.
Category baseline
The starting point for this type of product, before anything specific to this product is counted.
No PFAS disclosure
No public statement from the brand about PFAS in this product.
Fluorochemical migration from grease-resistant coating
Grease-resistant paper coatings in microwave popcorn commonly contain PFAS; migration into fatty foods during heating is a documented concern pathway, though Kirkland does not disclose whether its specific coating formulation uses PFAS or safer alternatives.
Thermal degradation of coating at microwave temperatures
Grease-resistant coatings may break down or off-gas at microwave temperatures if not formulated for this use; the extent depends on coating chemistry, but no independent testing of this product's thermal stability has been published.
What’s reassuring
BPA & bisphenols
No public information indicates BPA or BPS use in printing inks or bag assembly for this product; modern paper bag inks typically do not contain these substances, though the absence of disclosure makes full assessment impossible.
Source, FDA ↗Microplastics
Properly manufactured grease-resistant coatings should not shed into food under normal microwave use; however, bag degradation from puncture, overheating, or repeated handling could theoretically release coating particles, though this is not documented for this product.
Source, EPA ↗How is this PFAS grade calculated?
The brand's record and disclosure
Kirkland Signature (Costco's house brand) does not publish ingredient lists, material safety data, or coating composition for this product. No independent testing or recalls specific to PFAS migration from Kirkland popcorn bags have been published in the public domain. The brand's silence on fluorochemical use in food-contact coatings is consistent with industry-wide opacity on this issue; many manufacturers have not committed to PFAS phase-out in microwave popcorn packaging despite regulatory pressure in some jurisdictions.
How it compares in its category
Most conventional microwave popcorn bags, including major brands, use fluorinated grease-resistant coatings and do not disclose PFAS content. Some premium or specialty popcorn brands market PFAS-free or fluorine-free alternatives, using wax or silicone-based coatings instead, though these are less common in mass-market products. Kirkland's product sits in the typical commercial category; it is not distinguished by transparency or known chemical innovation compared to competitors like Orville Redenbacher or Act II.
If you buy it
Microwave according to package directions and do not exceed recommended cooking time, as prolonged heat exposure may increase migration risk from the coating. Open the bag carefully (contents are hot) and transfer popcorn to a separate bowl immediately after cooking to minimize contact time with the bag interior. If PFAS exposure is a concern for your household, consider buying bulk popcorn kernels and air-popping or stovetop-popping as an alternative. Store unopened bags in a cool, dry place away from direct sunlight or heat sources to prevent premature coating degradation.
What is not known about PFAS in this product?
- Basis
- Model estimate, 45% confidence, not a lab result
- Lab test
- None on record for this exact product
- Brand statement
- Kirkland Signature has made none
Formulations change between production runs, so check the current label. How we grade.
What are the PFAS-free alternatives to Kirkland Signature Microwave Popcorn Movie Theater Butter?
- puffed rice cakes in paperboard packaging
- We found no PFAS statement from the brand
- Mold or bacterial growth in packaging
- paperboard popcorn bag, grease-resistant interior lining
- We found no PFAS statement from the brand
- Moisture and mold risk if bag is compromised
- paper-based food packaging with standard coating
- We found no PFAS statement from the brand
- Ink migration (printing on exterior or interior)
3 hazards checked on this product, all on its full breakdown.
More microwave popcorn grades
How we score, every product runs through the same public 0-100 rubric based on materials, coatings, brand disclosure, lab findings, and recalls. See the full methodology → Spotted a mistake? Report an error.