We’re looking to go alcohol-free this year. I’ve been following the debate on printweek.com about how cutting back on alcohol causes emulsifying and scumming. How bad a problem is scumming, and what can we do to avoid it?

Many printers are actively looking to print with reduced or zero alcohol, and are concerned about possible side-effects such as emulsification and scumming. Eradicating these is largely down to the printer’s commitment, and isn’t at all investment-related: it’s all about ensuring good practice.

Are the rollers regularly deep-cleaned, and are they within the press manufacturer’s guidelines for hardness? Pressure settings as well as damp level and pan roller speed settings will need checking, and possibly readjusting, for the new dampening solution. New rollers could be required.

Printers should talk to their press supplier to get advice on their specific press, and detailed information should be obtained from the ink and chemical suppliers. Some inks will run more easily than others; there are differences between bio- and mineral-based inks. Ask for case studies, where success has lasted longer than a few months.

Once an agreed set of criteria and product has been defined, implement and maintain the quality checks. Some working practices may have to be changed, but this does not mean they become more difficult. It’s crucial to have clear objectives and buy-in by all shifts.

It will be important to arrive at a press setting with consumable chemicals that work together, but isn’t this the case at higher alcohol levels anyway? Make sure the chemicals being offered do not create more environmental impact or usage issues than the alcohol being reduced.

To maintain the stability of the whole process, controlling variables will also be necessary. Implement a robust maintenance schedule. Consider investment in a water treatment/reverse osmosis system, as well as improved filtration. These will prolong the life of the dampening solution, so reduce the volume of fluid for disposal. Filtration will also help keep dampening systems, pans and rollers cleaner.

Peter Benton, managing director, Technotrans

We’ve been asked by a customer to produce a game card that reveals when it gets hotter. I think we can do it with thermochromic inks, but how do we print with them?

There are two types of heat-changing inks: thermochromic and photochromic. Thermochromic inks can be activated by changes in temperature, and photochromic by UV/sunlight. Thermochromic inks can be reversible or irreversible – yours will need to be reversible, and as such will activate at a pre-defined temperature between -10°C and 70°C. Reversible thermochromics show their colour in their cold state, and disappear when heated, with black being the best colour to hide an image.

Thermochromic inks are becoming more popular as an attractive sales aid, and particularly for promotional devices. In the case of a game card that will reveal when heated, you would normally print the image by offset, and then coat over the top with the thermochromic ink. However, even an anilox coating device on an offset press achieves a thinner covering than screen process, and the reveal effect may not work well if offset is used. Instead, it’s better to do the coating using the screen process, particularly if you’re not flood-coating but only laying down a partial area of the thermochromic ink on the game card.

B&H not only develops and produces thermochromic inks, but also has much experience of printing with them, and has produced a range of products, including a Touch’n’Reveal effect. This uses a black hand-touch thermochromic ink that’s screen-printed down over the image to be revealed.

Thermochromic inks are available from B&H in screen, flexo and offset formulations, in a variety of standard colours. B&H can reproduce most colours to customer requirements; however, exact Pantone matches can’t be guaranteed. Custom formulations can be made up, for which the minimum order depends on the colour and activation temperature; if you order from stock, the minimum order is one kilo, and the inks have a shelf life of six months if stored in a cool, dark environment.

Gilly Beaumont, marketing manager, B&H Colour Change

We inherited a room full of different paper stocks when we took over a neighbouring printer last year, and some of it isn’t marked with a weight. Is there a simple way to find this out?

There are several ways you could do this, but none of them are particularly easy or quick. If it’s in reels, you’ll need to cut some accurate sheets from it; if it’s in sheets already, you’ll need to know their size.

Once you’ve got that, the fastest way to determine the sheets’ weight would be to plonk one on a set of digital paper scales, key in the sheet size and let it work out the grammage for you. I’m assuming you don’t already have one of these amazing gizmos, otherwise you wouldn’t be asking. Unfortunately, if you don’t have a set already, they’re not easy to buy. US manufacturer Ohaus makes a range of programmable scales that can calculate grams per square metre, but they’re not cheap – prices of models accurate enough for paper purposes begin at around £600. You can find Ohaus at www.scalesandbalances.co.uk. UK firm Paper Life used to sell a gadget known as the Digital Paper Scales, but sales came to an end a couple of years ago when the company ran out of stock; however, DPS Technologies, the original inventor of the scales, is soon to launch a new version.

If you don’t want to wait, there’s also an easy way that avoids the hassle of tracking down paper scales. Just get hold of a pair of normal electronic scales accurate to one decimal place or more. (You can even hire these for a specified period from Ohaus UK if you don’t want to fork out.) Measure one of the sheets, then lay it on the scales. To get the grammage per square metre, divide the sheet’s weight in grams by its length in metres and then by its width in metres. Thus, a B1 sheet weighing 78 grams and measuring 720mm x 1,020mm makes for a sum looking like this: (78 ÷ 0.72) ÷ 1.02 = 106gsm. Good luck – and don’t forget to keep it labelled once you’ve weighed it all!

Karen Charlesworth, post-press journalist