Compatibility Testing Tips

Your Container & Packaging samples just showed up and now the real work starts. Testing.

This is the part a lot of people skip. They open the package, hold a container up to the light, say “yeah, that looks good,” and order 500 units. Three weeks later, their product has eaten through the wall of the bottle, the lid popped off in shipping, or the label is bubbling at the corners. None of those are fun discoveries to make after the fact.

We’ve watched this happen. So here’s what to actually do with those samples before you commit to anything.

Step 1: Hold It First

Before you fill anything, just hold the container.

This sounds obvious, but just bear with us. Is the weight right for your product? A light, wispy jar can feel cheap holding a premium face cream. A heavy amber glass bottle might feel exactly right for an essential oil, or completely overkill for a kids’ shampoo. The container is communicating something about what’s inside it before anyone even reads the label.

Check the volume, too. Volume on paper and volume in real life don’t always agree. A “1 oz jar” can hold anywhere from 1.1 to 1.4 fl oz depending on the container. If your product needs to fill to a specific level for aesthetic reasons (like a candle jar or lotion container) you want to look full to the brim.

 

Step 2: Fill It With Your Actual Product

This is the compatibility test, and it’s the most important thing you’ll do with those samples. Fill the container, seal it, and then wait. Forty-eight hours minimum. A week is better.

What you’re looking for:

• Changes to your product — color shift, smell change, texture difference, or separation
• Changes to the container — softening, warping, discoloration, or the product visibly working its way through the container walls

That last one is called leaching, and it’s exactly as unpleasant as it sounds. We once had a customer fill 5,000 soft plastic bottles with a high-concentration essential oil blend. The product dissolved through the container walls and ruined both the oil and the bottles. All 5,000 of them. It was not a good afternoon for anyone involved.

Harsh chemicals, high-acid formulas, and essential oils are the usual culprits. But the only way to know for your product is to actually test it.

 

Step 3: Test the Closure

Now put the lid on. The actual closure you’re planning to use, with whatever liner you’re considering (if you have it). Then flip it upside down. Shake it. Throw it in your bag and carry it around for a day.

Your goal here is to make it leak. If it’s going to leak, you want it to do that now.

Liner choice matters more than most people expect. A few options to know about:

• Foam liner — a solid, versatile starting point for most products
• Pressure-sensitive liner — good grip and a clean peel; works well for a wide range of formulas
• Polycone liner — a good fit for liquids, especially anything with a pour spout
• Heat induction seal liner — hermetic (airtight) seal; the right call for anything with a strong chemical profile, an oily formulation, or a real leak risk

If you’re not sure which liner fits your product, that’s a great question for one of our consultants, there’s more nuance to it than a one-line answer can cover.

If you’re using a pump, sprayer, or dropper closure: fill it and actually use it. Cycle through it with your product. Some formulations will gum up mechanisms over time, especially anything with high viscosity or particulates.

 

Step 4: Mail It

Yes, really.

Fill a sample container, seal it, pack it the way you’d pack a real order, and ship it to a friend, or yourself. Then open the package and see what happened.

What you’re testing is whether the seal holds under real transit conditions, like actual truck, an actual sorting facility, actual vibration and temperature swings. The postal system is an undefeated stress tester and it costs about $5.

If it arrives intact: excellent. If it doesn’t: much, much better to know now.

 

Step 5: Drop It

Fill the container, seal it, and drop it from about three feet onto a hard floor. On its bottom. Then on a side. Then on a corner.

Does anything crack or shatter? Does the lid stay put?

If your product is going to be shipped to customers, it will be dropped at some point. The question is how forgiving the container is when that happens. Thick-walled plastic tends to be forgiving. Drop glass at your own risk. Glass is beautiful and feels premium but also has strong opinions about concrete floors. (We mention this upfront. We think it’s only fair.)

For products that will be stacked in storage or shipped on pallets, compression matters too. Stack a few filled containers on top of each other and see how the bottom one holds up over a few hours.

 

Step 6: Test Your Decoration

Once you’re confident the container works with your product, think about your decoration.

Different container materials hold labels differently. HDPE plastic has a slightly waxy surface that some label adhesives don’t grip as well as they do on PET. If your product sweats condensation on the outside (common with anything refrigerated or cold-filled) or if it’s prone to minor leaking at the closure, some printing methods will smear.

Get a sample label printed, apply it to your container, leave it for a week, then try to peel it. If it comes off clean, you’ve got a surface adhesion problem worth solving before your full label run.

Container & Packaging doesn’t sell labels directly, but we do offer label design, file prep, and printer coordination through our Labels & Printing service. If you need help getting from “I have a design” to “I have labels that actually stick,” that’s something we can walk you through.

 

The Part Where We Mention Our Sample Program

This will come as a tremendous shock: the blog post hosted on our website is about to recommend you order samples from Container & Packaging. Take a moment.

If you haven’t already, our sample program lets you try up to 10 qualifying items for just the cost of shipping ($7.50 in the US, $15 for Canada.) No minimum order, no commitment. Get the containers in your hands so you can run through everything above before putting real money behind your decision.

And if you’ve already got samples but have questions about what you’re seeing (or not seeing) in your testing, give us a call. (800) 473-4144. A real human will pick up.