For the sake of full disclosure, I am making a link to each of the products that we use, but I am not the seller of these blanket thickness measurement tools. It is just meant to show you the tools I have personally used and my review of them. Feel free to get your tools elsewhere.
These tools are the tools I have used for measuring blanket thickness. There are generally just these three. If you know of another, please mention it in the comments.
1. An Outside Micrometer
Every offset printer should have one of these. Here is the one we use. They are the easiest to acquire and most hardware stores have them.
Advantages
- Cheap. Most cost under $30. The digital ones are a little more, but I don't recommend them. See third bullet point.
- Accurate. Fairly. As long as it's not dropped or abused in any other way.
- Resistant to solvent. This one is not digital and we don't have to worry about exposure to chemicals or ink.
Disadvantages
- Must be stored in a case. Just bumping it against other tools can cause it to lose calibration. It must be stored carefully.
- Not as practical. It does not tell you the actual blanket measurement when mounted on an offset press. This is what counts at the end of the day, right? Can be time consuming if the blanket must be taken off the press to be measured.
- Versatile. Can be used in numerous applications. Measuring packing and plates is also possible.
This type of blanket measurement tool is great for quality control. Especially when blankets newly arrive to the press room. Each blanket can be checked for quality from the manufacturer.
As a side point, this one is not spring loaded. I know that some prefer this, but I have used both and see no difference.
2. Blanket Packing Guage
I couldn't find the exact one being sold online, so I will just attach a picture of ours. This one probably gets used the least because of an upgrade we did a few years back (see tool number three). However it does the job well and measures the true height of the blanket over the bearer. In offset printing that is the REAL measurement that tells you what is happening.
Advantages
- A true measurement. Taken when the blanket is mounted.
- No need to remove the blanket.
Disadvantages
- Cost. Checks out at around $300. Not bad. If you search online, that is about the going rate for a good one.
- Cumbersome measurement. It relies on laying squarely against the blanket which can be difficult to do. I find myself constantly second guessing it.
- Sensitive. Dropping it or bumping against other tools causes it to lose calibration.
I prefer not to use this blanket measurement tool because of the nature of how it works. It must sit flatly on the blanket to get a proper reading. Blankets swell depending on heat, age or piling at different stages of a print run. Sometimes you mustmeasure at different places. For example, you might be measuring at a low area of the blanket.
Coating Thickness Guage
By far my personal favorite. After using this for a few years, I highly recommend it. Here is the exact one we use.
This is essentially a paint thickness gauge. It is mostly used in auto body shops by painters to measure the thickness of paint. It measures the distance to a metal surface from the sensor. You put the sensor on the blanket and it measures the distance to the cylinder: blanket + packing.
We had to do some trial and error with this one. It around $1000. There are cheaper ones out there, but they give inconsistent readings, even when measuring the same spot. Others only used metric. Turns out that it's worth the extra few dollars for a good one. This one gives us consistent and accurate readings.
We also found that it's important to have the extension (the attached black wire and sensor pictured below). When reaching over the web on a web press or just trying to use it in tight spaces, it proved very helpful.
Advantages
- Gives the actual blanket height from the cylinder.
- Can measure even small spots on the blanket. Can tell you if there are low spots, or even if the blanket is smashed in a certain area.
- Fast. No need to dismount the blanket.
- Not a sensitively calibrated instrument. Ok, it is, but it's not like if you bump or drop it and it's useless.
Disadvantages
- Not resistant to solvent or inks. You have to store it in a dry place and keep it clean.
- Cost. Sets you back about $1000 if you want a good one.
More offset printers are catching on.
The company that makes this product is catching on and I notice they are advertising it to the printing industry. They market it specifically as an offset printing blanket thickness tool.
But I have to say that I think they incorrectly say it measures mounted printing plates. It can't since the plates are metal and so could not measure the distance to the cylinder.
Blanket thickness measurement is critical.
Offset printing blankets are a critical measurement. Any press operator knows this. With instruments like I just mentioned, it's not a guessing game as to when it's time to change blankets.
We generally get 10 million impressions from our blankets. But measurement tools like this tell you if you can go for another million, or if you need to change them earlier. There's no guesswork with this critical measurement.
Conclusion
I hope your offset printing press can benefit from one of these tools. They have certainly helped on our web and sheet fed presses since we can share these measurement tools with each press. Don't cheap out. They are worth it!
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