Exploring Glass, PET, and LDPE Plastic – A NoTE Flavors Packaging Case Study



10mL Erythritol Bottle in Clear PET

Every Month, NoTE Flavors ships hundreds of parcels to consumers. When we first started our company, we offered our product in only one size – our humble 10mL plastic bottle. When we designed our packaging for this bottle, we grappled endlessly over which variety of plastic would best meet our needs. While LDPE is popular, affordable, and highly flexible, LDPE is only partially transparent, and left our liquid with a white tint that we felt appeared cheap and failed to display our products to customers in the best possible light. However, PET, another relatively common plastic, is clear, durable, and gave our products a glossy, even glass-like appearance that screamed “premium” while still being extremely affordable. Although PET is our plastic of choice, it is relatively inflexible and can be difficult to squeeze when mated with our dropper tip and cap. With a simple, yet elegant label, our planning was complete and we were left with a product that we are proud to sell to consumers all over the country. The choice was, and still is, extremely clear.

10mL LDPE Bottles, 50% Translucency

We continued on this path with our 30mL bottle size, which launched shortly after our 10mL Bottle. Our 30mL Bottle uses the same dripping mechanism as our 10mL bottle and is the same height as a 10mL bottle, but has a wider base to accommodate the extra 20mL of liquid inside. With even more space available, PET showed off our products in a way that we have always intended them to be seen, at a price comparable to that of LDPE. Since most of our flavorings are highly viscous, the issue of flexibility remained a minor one on our bottles that featured our dropper tip. None of our flavorings are to be dripped at above 10% when used as recommended, making the problem more into a feature of our bottles, as customers enjoyed the control they had over the flow of the liquid into the end solution. Liquids in LDPE bottles tend to flow freely when even lightly squeezed, but our PET bottles showed much more resistance, stopping the flow of liquid entirely when normal pressure exerted from holding the bottle is applied. However, the supplier we had worked with to source our PET bottles couldn’t help us when we planned to launch our 60mL and 120mL sizes, as most US-based suppliers only stock 10 and 30mL bottles in PET. In larger sizes, such as our 16oz and 32oz bulk bottles, the bottles are widely available. However, we were left with two options for our 60mL and 120mL bottles. LDPE and Glass, which left us puzzled as to how we would choose between two materials that we had eliminated earlier in the planning process.

Menthol, 30mL in Clear PET

When considering appearance, Glass was the obvious winner. A glass bottle is almost always as clear as a PET bottle, and offered the shiny, premium appearance that emphasized quality and set our products apart from the rest. However, the obvious issue, breakage, was overlooked, as we were sure additional bubble wrap and better packaging guidelines would eliminate the problem. We loved the way our glass bottles looked and felt, and our first customers did as well, so we had little worry about choosing glass as our bottle of choice for all bottle sizes above 30mL. As any bottle size above 30mL is difficult to squeeze, and in the case of glass, impossible, we did away with our drip cap on all sizes above 30mL. Our larger bottles are targetd to experienced DIYers, Vape Shops, and other experienced or professional customers, for whom a drip tip would get in the way of a precise, lab grade syringe when mixing up a batch of E-Liquid. In this way, we were correct, and our customers enjoyed the wide mouth our larger bottle sizes offered which was large enough for a 10mL disposable syringe. However, the image to the right is no accident, as breakage claims quickly became a problem that afflicted our business with an urgent issue that required prompt action.



We’ll take a deep dive into the fragility of glass bottles and explore the viability of using a glass bottle with your product. Our data is based on actual consumer transactions and scientific drop tests of multiple units of the same brand of 60mL glass bottle.

Testing: How easily does a glass bottle break in the mail?
NoTE Flavors 60mL Glass Bottle, Baseline Drop Test on Production Floor

When determining how easily something will break, the easiest way is to break things. To set our baseline, we threw one unprotected glass bottle in an underhand throwing motion, similar to the motion used by a USPS employee or sorting machine when sorting first-class packages. The bottle was thrown approximately six feet underhand from our shipping station onto our concrete production floor, and it shattered on the first attempt – as expected!

Our next test involved throwing our glass bottle protected within a standard Kraft bubble mailer, affixed with a shipping label, in the same underhand motion. The bottle, in this test, is not protected by any secondary bubble wrap. It is simply padded with the bubble wrap included in the mailer and the paper that makes up the bubble mailer. The bottle was unharmed. However, we knew our bottles were occasionally broken in transit. Based on actual customer images, we knew they were breaking on the bottom. Therefore, our second test involved dropping the mailer, bottom-down from eight feet in the air onto our production floor. Again, the bottle was not harmed, even after the same drop was repeated three different times.

Therefore, we were able to eliminate throwing as a source of breakage when the bottle is protected by a standard bubble mailer. However, an even more common source of trouble for fragile packages in the mail occurs when a heavier package is thrown on top of a light parcel. In this test, we dropped a three-pound package three feet onto the protected glass bottle. The bottle survived, completely unharmed. At six feet, it, again, was not harmed. Now, we threw this package in an underhand motion at the mailer, which was placed on the production floor. It remained intact. Clearly, our standard bubble mailer had made all the difference.

However, on our final test with unprotected bottles in a bubble mailer, we increased the parcel’s weight to 10lbs. On our three foot drop test, the bottle failed – catastrophically, breaking into very tiny pieces. Since items mailed First-Class or Priority Mail could, in theory, be co-mingled with packages up to 70lbs, this final test essentially proves that any breakage is occurring due to co-mingling with heavier packages, and not throwing or other bad handling practices.

Finally, we packaged the item in the same way it would be sent to an actual customer. When we send a glass bottle to a customer, we use a variety of safeguards to protect it from breaking in transit. Every order discussed below was packaged in this way, leading to the break rate that we have disclosed. 

  • The bottle is bubble-wrapped within the bubble mailer, resulting in double the amount of protective bubble wrap.
  • The mailer is surrounded by two air-cushions by Sealed Air, providing side-drop protection and protection from heavy packages.
  • The mailer and air cushions are enclosed in a protective poly-bag, and a shipping label is affixed to the poly-bag.
NoTE Flavors 60mL Plastic Bottle, 10lb Crush Test

In this test, we subject the bottle to our 10lb package that caused the bottle to fail in our previous test. When this 10lb package is dropped at a height of three feet, the bottle survived, however one of our air-cushions was deflated. However, it is still intact and deliverable to the customer. When we subjected the bottle to a 6ft drop of a 10lb package, however, the bottle, again, failed catastrophically. By this testing, we are able to determine that most, if not all, of consumer-reported breakage occurs when a heavy package is dropped three to six feet onto one of our packages.

The Data: Consumer-Reported Break Rates

In this dive into the analytics that prompted our research into the viability of glass bottles, we take a look at a sample of 100 orders placed in the month of October, 2017. In this sample set, 39% of the orders contained glass bottles. The other 61% were 10mL or 30mL PET Plastic bottles. Therefore, we’re looking at 39 shipments of glass bottles sent via USPS First-Class Mail. Of that set of 39, three of these items were replaced or refunded after breaking in transit. Effectively, we’re dealing with a break rate of 7.69%. Not very good! Of course, all of these 39 orders were packaged according to the packing standards disclosed in our final test. Therefore, our packaging is effective in 93% of cases, however, a customer that receives a broken item is likely to be unhappy with his/her purchase, unlikely to buy again, and result in a loss on that order as a refund or replacement is required. At NoTE Flavors, we strive for a better customer experience, and there is little reason you should not want to reduce your break rate as well, as each broken order is a lost customer, and possibly a lost referral of another customer due to word-of-mouth. Also, it is lost money, as refunding three orders per month due to breakage – which is irrecoverable as the customer cannot return the item to be resold – would cost the seller $60, assuming an average order value of $20.


Glass Bottles, generally, are also more expensive to ship. A factor affecting breakage is the thickness of the actual glass – in theory, a thicker glass results in less breakage, or at least, less catastrophic failures. However, you can expect to pay a premium for thicker bottles, as they require more raw materials to make and are therefore more expensive to order. A thicker bottle is also heavier, which could easily put you over your goal shipment weight and cost you more money at the post office. When you ship a First-Class Mail package at USPS Commercial Base or Commercial Plus rates, you can expect to pay a flat rate of $2.61 for any package up to 4oz. A second tier applies, offering a flat rate of $2.77 up to 8oz, based on 2017 prices. Once your parcel weighs in at 8.1oz, however, you’re moving out of the flat rate structure and you will begin paying a premium for each additional ounce. Therefore, our goal has always been to keep our packages below 4oz, and below 8oz where the former is not possible.

However, our glass bottles, filled with NoTE Flavors Liquid Menthol Crystals, weighed in at the 10oz rate. When the bottles were filled with NoTE Flavors Liquid Erythritol Sweetener, the bottles weighed in at the 11oz rate due to the density of the liquid. An 11oz package will cost $3.60 to ship, and a 10oz package will run you $3.46. Reducing the weight of these packages to 8oz will save you $0.69-$0.83 per order. By switching to glass, we were able to reduce our shipping weight for all of our 60mL bottles from the 8oz rate to the 4oz rate, and for our 120mL bottles, from the 10-11oz rates to the 8oz rate. Hypothetically, if you were to ship 100 orders, 50 of them 60mL bottles and 50 of them 120mL bottles, you’d save about $50 per 100 orders. As plastic bottles are nearly immune to any sort of catastrophic failure, you’ll also reduce your packing supply costs as the bottles do not have to be bubble wrapped or secured within Sealed Air mailers. Therefore, you will also not need an outer poly-bag, and can ship your bottles directly within a bubble mailer. Depending on your costs for these items, this can also lead to a notable reduction in shipping and shipping-related costs.


NoTE Flavors Wide-Neck 120mL Plastic Bottle

As of November 1st, 2017, all NoTE Flavors products are sold in PET plastic bottles. While 60mL and 120mL plastic bottles are harder to source from a US-Based company, there are options available, and there are rewards to be had for finding and sourcing them. At NoTE Flavors, we do not buy from China. In fact, we do not buy or ship anything to a customer that is made overseas, and we pride ourselves on our commitment to the quality and safety of our products, as well as the greater good of our nation by not doing so. Regardless of where you source, our research concludes something as simple as making the switch from glass to plastic can lead to increased customer satisfaction by eliminating costly breakage that turns off customers. Rethinking your packaging can also help your bottom line – making the switch can save you $100-$200 per 100 orders – without factoring in the revenue lost by turning off repeat buyers. You’ll also eliminate the customer service and logistical nightmare that arrives when an order is delivered to your customer’s door in poor condition, which can be an expensive and confusing situation, especially if you are shipping internationally.

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