Let's be straight with you, even a tiny patch of uneven wear on a rubber roller is a high-priced disaster waiting to strike.
It leads to messy line snaps and ruined production schedules. That’s why a rock-solid pusey & jones hardness test is the only way to keep your machinery running like a dream.
We’ve put together this guide to show you the nuts and bolts of getting this specific P&J hardness test spot on every single time.
Key Takeaways
- The pusey & jones hardness test is built from the ground up for the thick rubber covers on massive industrial cylinders, making it far superior to quick jabbing tools designed for flat plastics.
- Following the strict ISO 7267 rulebook ensures your quality checks actually reflect reality on the factory floor.
- Because thick rubber is a slow-moving material, letting the heavy weight sit for exactly 60 ticks of the clock is the absolute most critical part of getting a proper reading during a P&J hardness test.
- Flying blind on the true squishiness of your rollers leads directly to snapped paper lines, trashed materials, and massive cash burn.
- Upgrading to an automated digital setup takes the human factor out of the mix entirely and gives you highly reliable numbers you can bet your production schedule on.
What is a P&J Hardness Test?
The P&J hardness test (which is just short for Pusey & Jones) is a highly specific way to figure out the exact level of "squish" in your rubber or elastomeric materials. We think it's important to see this as more than just a quick poke: it’s a method built specifically for those thick, heavy-duty rubber skins found on rolls in the paper and tissue business.
To keep quality levels consistent across the globe, a proper Pusey & Jones hardness test follows the strict rules of international standards, specifically ISO 7267. During this process, a perfectly round ball indentor is pressed into the rubber surface using a heavy, constant load (usually weighing exactly 1000 grams) for a full minute. We measure how deep that ball sinks.
Every tiny bit of depth (0.01 mm) counts as one P&J unit. We find it helpful to keep in mind: if the rubber is soft as a marshmallow, that ball sinks deep, and your P&J number goes way up.
Research has confirmed that the size of the ball is a critical, controlled parameter for any pusey & jones hardness test. Most testing setups use either a 1/4-inch or a 1/8-inch diameter ball to ensure the readings are meaningful for the specific rubber type being checked.
To give you a totally clear picture, think about a hypothetical heavily compacted calendar roll pressing thick paper board. That surface needs to be incredibly unyielding, so it might register a very low P&J number. On the flip side, a super-squishy tissue machine roller needs to be soft and pliable, meaning it will rack up a much higher value during its P&J hardness test.
Step-by-Step: How to Perform a Pusey & Jones Hardness Test
Getting the right numbers is everything when you’re evaluating your rubber rollers. Whether you’re looking at a brand-new roll or trying to see how much life is left in a heavily used one, following a tight plan is vital. We believe that keeping your testing spot consistent is just as big a deal as the tool you're using.
If you’re trying to figure out how to perform a pusey & jones hardness test, follow these essential moves:
1. Ensure the testing environment is stabilized
Rubber is surprisingly moody when the temperature changes. We suggest making sure both your testing gear and the big rubber roller have sat in a comfortable, normal-feeling room (around 23°C or 73°F) for a significant amount of time before you start your P&J hardness test.
If a roll just came off a blistering hot production line, it will naturally read much softer than it actually is. If things are too hot or cold, your data will be all over the place.
2. Give the surface a thorough cleaning
You need to make sure the part of the roller you’re touching is totally free of dust, old ink, paper scraps, or greasy buildup. Even a practically invisible layer of leftover chemical residue or a tiny speck of dried paper pulp will block the indentor ball from making pure contact. We believe a completely clean surface is the only way to get a reading that actually means something during a pusey & jones hardness test.
3. Position the testing equipment correctly
Carefully set your P&J plastometer down on the curve of the roller. Because you are dealing with a curved object, finding that absolute top-dead-center spot is absolutely critical for knowing how to perform a pusey & jones hardness test correctly.
That machine has to sit perfectly flat and steady so the ball pokes straight down at a sharp 90-degree angle. If the device leans even a fraction of a degree down the slope, the ball will slide rather than sink. No wobbling or shifting allowed!
4. Engage the rubber and reset the display
Lower the chosen ball indentor until it makes firm contact with the rubber surface. This step establishes your absolute baseline. You want the indentor resting snugly against the material without actually pushing into the cover yet.
Hit the zero button on your screen or dial so you’re starting from a fresh slate. If you want absolute certainty for your P&J hardness test, verifying your zero-point calibration on a solid RUBEN laboratory measurement base beforehand is a brilliant move.
5. Apply the constant load
Release the standard 1000g weight so it pushes down on that ball indentor. Make sure this action is incredibly smooth and controlled. Jerking the release mechanism or slamming the weight down creates an artificial impact spike that completely throws off your starting position before the clock even starts.
6. Monitor the clock for 60 ticks
Now, you wait for exactly 60 seconds. Because rubber has that thick, slow-moving quality, it fights back against the weight, yielding gradually millimeter by millimeter.
We think the timing is the most important part of the whole manual process.
Those last five seconds are just as crucial as the first five. If you stop too soon or wait too long, your final numbers for the pusey & jones hardness test will be total junk.
7. Record your final measurement
Once that minute is up, check the depth.
The best modern digital tools will do the math for you and show the P&J value right on the screen. No scratchpads or manual calculations needed. To get the full picture, don't just poke it once in the middle and call it a day.
We suggest taking several different pokes all the way across the length of the roller, checking the edges, the center, and everywhere in between, to make sure the hardness is uniform from end to end and to catch uneven wear patterns early.
P&J Hardness Test vs. Shore Hardness
You might be thinking, can’t I just use that little Shore A clicker I have in my pocket? While Shore tests are great for flat bits of plastic, we think the pusey & jones hardness test is a much better choice for those massive, moving industrial cylinders.
Shore tests give you a quick jab with a tiny needle. But the P&J way uses a much bigger ball applied for a significant amount of time. Because thick rubber is a slow-moving material, it gives way gradually under pressure. In our view, that full minute of waiting gives you a much better idea of how that roller will actually act when it’s under the non-stop, heavy-duty pressure of a working paper machine.
Think of it this way: if you are checking the firmness of a rigid plastic gear or a solid forklift tire, that quick-jabbing Shore test is the perfect tool for the job. But those items don't behave like a massive, slow-yielding nip roller that applies continuous pressure to a fast-moving web. That kind of hefty machinery absolutely demands the full, sixty-second P&J hardness test treatment to get numbers you can actually rely on.
Interestingly, research shows that P&J readings can be systematically converted to equivalent readings on other instruments like Shore or Schopper using correlation curves. This means that while the pusey & jones hardness test is your primary tool for rollers, you can still translate that data to other scales when necessary.
The Cost of Ignoring Roller Hardness
Blowing off your regular checks or guessing based on bad data is a total coin toss with your profit margins.
Consider a totally hypothetical scenario: a major packaging plant starts experiencing non-stop web breaks on their primary line. If they haven't been checking their numbers, they might not realize a massive press roll has slowly hardened into a solid block of concrete over a six-month period.
A situation like that burns through a massive pile of cash in lost production time and trashed materials, all because nobody took sixty ticks of the clock to check the rubber with a proper P&J hardness test.
We believe that operating without knowing your roller’s true squishiness leads to some ugly results:
- If a roller is hard as a rock: It’s going to snap your paper sheets, crush the delicate fibers, or wear out the expensive metal parts it touches.
- If a roller is soft as a marshmallow: You’re going to get inconsistent ink transfer, weird heat buildup, and a roller cover that might actually fail mid-job.
In our opinion, regular checks let you see the wear coming so you can schedule maintenance before the whole line grinds to a halt.
The Shift to Automated Testing
The old-school dial gauges can get you there, but they are magnets for mistakes. We’ve seen how easy it is to read a needle wrong or be a few seconds off on the timer. In a business environment where every penny counts, we believe being "close enough" just isn't good enough for your pusey & jones hardness test.
Moving to an automated, digital setup, like the patented Ruben measurement device we offer, takes the human factor out of the mix entirely. In our view, having a machine that finds the surface on its own and shoots all the data straight to your computer via programs like the RUBEN Explorer PC software is the only sensible way to handle quality control currently.
Get Precise Pusey & Jones Hardness Test Results at Qualitest
At Qualitest, we believe peak production requires gear you can bet your life on. We provide top-tier accuracy without emptying your company bank account. Our cost-effective P&J Plastometer – Pusey & Jones Hardness Tester is a reliable, ISO 7267-compliant machine that automates the 60-second wait for you.
Stop guessing and start knowing exactly how to perform a pusey & jones hardness test with precision. Ready to save some serious cash? Check out our P&J Plastometer today and see how our products make your life easier.
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