Printing accurate barcodes on thermal printers
What are thermal printers?
It might be tempting to use a desk-top ink-jet or laser printer to produce labels when you first start to need them, but they are not always the best for printing barcode labels.
Thermal printers are still digital, but they are industrial machines, with fewer moving parts than other types of printer, and are highly reliable. Rather than using toner or wet ink to create the printed image, thermal printers use hundreds of tiny individual heating elements to either activate thermocromic/thermal material (direct thermal) or to transfer pigment from a ribbon (thermal transfer).
The size of the print elements can vary and are typically referred to as the DPI (Dots Per Inch). A higher dpi will enable you to print finer lines, increasing the range of barcodes that you are able to create and also improve print quality of text and images.
If not all, the majority of thermal printers are supplied with a software package. This will comprise the drivers you will need to connect the printer to a PC and will also have a label design element. This will enable you to create labels of any size and populate them with images text and barcodes.
Barcodes created and printed using this software can be extremely accurate, especially if the bars are printed in picket fence format. The software matches the width of the bars to a complete number of printhead elements or dots – you cannot print a bar that is, say, three and a half printhead elements wide. The higher the printhead resolution, the DPI, or dots per millimetre in metric , the greater the choice of possible barcode sizes. Barcode sizes can be defined by the width of the narrowest bar (the x-dimension) or by magnification for some symbols, such as EAN-13s. So you cannot accurately print barcodes of any size, but here is a link to the sizes that you will be able to create and where in the retail supply chain these would be accepted.
Link needed here!
Printing directly from the supplied software package or one created specifically for thermal printers will give the best possible print quality.
Once the printer has been installed it should be possible to print to this just like any other printer, using Word, InDesign, Adobe Acrobat, etc… and the results can be disastrous.
As outlined above, all thermal printers are restricted by the dot size – It is impossible to print half a dot. A barcode imported into a design package may not match the DPI of the printer. When this happens, the printer will either round up or down the width of the bars to the closest available size. The barcode will retain the same overall size, it will however, most probably fail to reach the print quality standard required.
Even if the bar width did match the DPI, each bar would need to be aligned exactly with the dots. Highly unlikely. It may be possible to improve the quality of the barcode by moving it fractionally to the left or right, but realistically, this is all but impossible and the problem of the dot size would remain.
Other print quality considerations
We’ve established that starting with the best possible barcode image is vital, but this will not guarantee scannable barcodes. There are additional steps that can be taken to help maintain print quality including.
Matching thermal ribbon to substrate. Thermal ribbons come in a wide range of grades. The type of ribbon required will depend on the make of printer and also what label material is being used - synthetic materials and paper will need different types of ribbon.
Orientation. Barcodes will print better if they are printed in picket fence rather than ladder format.
Creased ribbon. It is vital that the media is loaded in the printer correctly and that the ribbon is only marginally wider than the label and the backing material. The printhead must to be correctly aligned with the print roller. Failure to do this can mean that diagonal white lines may appear across the barcode. Print that is close to the edge of a label can also cause the ribbon to crease.
Printer settings & upkeep. The temperature/density and speed of the printer must be set correctly and be suitable for the material and design of the label. Dirty or damaged printhead and/or rollers will also reduce the print quality. It essential that the manufacturers guidelines are followed and regular cleaning and preventative maintenance is carried out.
Quality control. Last but not least is quality control including the use of a barcode verifier which should be carried out throughout the print run.
Axicon Labels supply a range of thermal printers and consumables. Our parent company Axicon Auto ID is recognised across the globe for its expertise in barcode verification. For further information on any aspect of barcode quality, please do not hesitate to contact us.
Digital printing for personalization
The latest development in label production, digital printing, means that we can produce specialised full-colour labels in much smaller production runs than ever before. Producing labels with changing data, for example, sequentially numbered barcode labels, has been possible for some time with thermal transfer printed labels, but they have only been available in two colours, usually black and white.
We can now use similar techniques that use data included in spreadsheets to produce labels in full colour that include customer-specific information. Names on personalised labels? No problem.
Naming labels may not be your challenge, but having twenty different versions of basically the same product label for a product produced in small quantities could be. It might not be just words that need to change for each product, but also some aspect of the artwork such as a logo or other graphic.
What all this means is that specialised runs of labels can now be produced in smaller quantities than ever before, at a reasonable cost, without committing to expensive printing plate changes. Labels are printed, varnished or laminated and then cut in a single pass on our Mark Andy Digital One printer. The ability to do this as one process is key, reducing set-up time, material and waste.
So what has Axicon Labels done that shows off these capabilities? One recent customer has 24 different versions of the same product that needs two labels, one for the front and one for the back. By looking at this job as a variable data one, and using our Mark Andy digital printer, we were able to produce batches of between 250 and 1,000 of each label, 32,000 in total, within 3 days, and at an acceptable cost.
Sometimes the personalisation has to happen a little closer to the customer, which is what Reese’s needed for their Peanut Butter Chocolate Spread promotion for Christmas. We printed labels with space for a name, then provided Selfridges with over-printing equipment so that named jars could be produced on-site, and sold in their London, Birmingham and Manchester stores and on-line.
So what could we print specially for you? Please get in touch with us to discuss what is possible, and see how we can make your products look as special as you know them to be.
Adhesives – An overview.
You need a label. You need it to stay stuck…. But what to? For how long? At what temperature?
Getting a label that sticks may seem not too much to ask, but one of fundamental challenges for a self-adhesive label supplier is to ensure that the adhesive on your labels is the best possible match for your product.
Permanent labels need to stay on; removable labels need to peel-off; re-sealable labels need to stay on, then peel off, then stay on and then peel off and then…. you get the idea.
Having a clear understanding of your products and how you envisage the labels working on them allows us to advise on the best solution as well as being able to provide an accurate quotation. Supplying an unprinted sample for testing shouldn’t be a problem.
This is the term used to describe the strength of the bond that the label will have when initially applied. This ranges from low to extremely high. If you are hand applying labels to a jar and need to ensure that they are straight, you would need a lower initial tack so that these can be repositioned. Whereas machine applying outer case barcode labels to corrugated board on a conveyor will require a much high initial tack.
If you try to remove a permanent label immediately after applying you may well find that it will peel away from the surface. However, in time the adhesive will set and give you a much better indication of the long-term performance. We typically suggest that you leave this overnight.
Long Term Adhesion
The world of adhesives is extremely technical and full of jargon. Essentially there are two types of adhesives.
Permanent labels are designed to stay on your product for the length of its life. It may not be impossible to remove these labels but they should remain in place during typical handling. There are factors including changes in temperature or humidity that can affect this.
Removable labels are designed to peel away without damaging either the product or the label. As well as the factors above, the length of time the label is stuck on will affect how well it peels off.
Within these two categories are a multitude of variations taking into consideration specific requirements including temperature, the surface that they will be applied to and whether this is textured, curved, uneven or even greasy.
The technical term for this is the long term adhesion of the label. It’s important to know that this is not an arbitrary measure - permanent adhesive should be permanent no matter who supplies it. These standards are specified by FINAT - The European association for the self-adhesive label industry (https://www.finat.com/knowledge/finat-test-methods).
The look of your label is important. You’ve spent a great deal of time and money on the branding, design and finish of your labels. If it is poorly positioned or peeling away, all of that is undone in an instant.
A good label supplier should help you by ensuring that all aspects of your label are fit for purpose and especially the unsung hero – the adhesive.
"The advice on how to re-plan our label production, and use our in-house equipment more efficiently alongside Axicon printed stock has been a major help"
Axicon have helped us get out of numerous sticky situations with understanding, speed and good humour! They’ve made the whole process of getting our labels printed easy and it’s nice to know we can outsource something like this to the experts. We can’t recommend them highly enough!
Doisy & Dam