Introduction
Press chemicals, plate washes, roller and blanket wash-up solvents together with fountain solutions and maintenance materials form an important part of this section. Other items such as devices for testing the emission of UV lamps and others for measuring the gloss of a coated surface are also covered, giving the reader a fairly comprehensive view of the materials and accessories used in conjunction with UV printing and coating.
Topics covered in this section are listed below:
Fountain solutions or additives 
Plate cleaners 
Cleaning solvents for blankets and rollers Hand cleaners and protective measures.

Accessories
(a) Testing equipment for lamps.
(b) Other materials for testing lamps.
(c) Testing equipment for gloss measurement. 
 

Fountain solutions
Fountain solutions or fountain additives for use with UV are mostly those which are also compatible with alcohol. This is a natural development as most presses in the sheet-fed and web-fed offset field are no longer supplied with cloth covered dampeners unless specified by the customer. 

There are specific fountain solutions which have been formulated for use with UV products, and these work efficiently with a wide range of presses and water differences. However, it has also been found that many fountain solutions formulated for conventional inks are also compatible with UV products. Solutions which have performed poorly in the past have one thing in common: gum, whether synthetic or natural. Generally, these solutions do not work as well as solutions without gum.
Consultation with your fountain solution supplier will ascertain whether or not a specific product is deemed suitable for use with UV. Most suppliers will have, as stock, solutions which will perform satisfactorily. So there should really never be a problem with finding a compatible fountain solution.

Plate cleaners
Proprietary plate cleaners which have become so commonplace over the past couple of decades are not all suitable for use with UV inks and varnishes. It is not because the cleaners themselves are poor, but rather that UV inks and varnishes are more difficult to remove from the image.
Some printers try every cleaner on the market in an effort to find a compatible one. Others simply resort to a well-trusted and reliable plate wash, followed by the plate cleaner which they have used for years with conventional ink. 

Both methods ultimately give satisfactory results, with the second method somewhat more economical.
It has been found, however, that some cleaners, when used with UV inks, have a tendency to badly stain the plate. As these stains sometimes “build-up” on the run, these cleaners should be avoided. Most proprietary plate cleaners, though, are suited for use with UV products.
 

Cleaning solvents for rollers and blankets
Solvents for cleaning should be used in the recommended manner specified by the manufacturer. If a roller wash leaves an oily deposit on the surface after cleaning, then the deposit requires flushing with a secondary wash. This should leave the surface clean, dry and ink receptive. If the oily deposit is left on the rollers it may be intermixed with the next color to go on the rollers and will, in all probability, cause trouble with curing. This is because the roller-wash solvent mixes with the ink, which, after transfer to the substrate, is passed under the lamp. Curing is impaired by the solvent being entrapped in the ink film. The only correct solution to this problem is to wash the rollers again, using the proper procedure. Only solvents specifically formulated for UV use should be used. If other solvents are used, damage can result to rollers and blankets if the particular solvent is not compatible.
 

Hand cleaners
As a general guide the hand cleaners which serve so well for conventional inks also are usually adequate for UV. Hand cleaners are available which contain an abrasive, usually pumice, and this is excellent for removing all ink and dirt residue. Solvents should never be used to clean hands or skin as the natural oil of the skin is removed. This allows solvent/ink mixture to penetrate into the inner part of the skin, possibly causing dermatitis. Proper hand cleaners prevent this problem by maintaining the natural oil in the skin’s surface. 

As with the handling procedures for oil-based inks, gloves should be used to prevent soiling of the skin when handling UV products. As the solvents used for cleaning rollers and blankets remove the natural oils from the skin very efficiently, and such contact may allow inks to penetrate the skin, gloves are a tried and proven method of hand protection.
The use of protective creams to preserve the skin is also recommended. As the purpose of these creams is to prevent initial penetration of the skin, products in this category can be classified as preventative rather than medicinal. 

It should be noted, however, that protective creams should not be used if there is any probability of transfer to the printing substrate during handling.  As UV inks do not print over fingerprints, the product will be flawed. Gloves should also be used to prevent heavy soiling of the skin.
Precautions for skin and hand care should also be observed when handling conventional ink and similar products as the effects on skin can ultimately be the same. 

Methods of measuring UV output: Conveyor-type units
The measurement of available UV energy from a lamp mounted onto a conveyor is usually performed in one of two ways:
The first is an extremely simple test using a specially prepared self-adhesive tape. These materials are light sensitive and react according to the intensity of the UV light. Typically a green colored tape is attached to a sheet of paper, preferably across the full width of the sheet. Another method features small strips spread intermittently across the sheet. The sheet is then passed under the lamp. This is done when the lamp is new, and has been operational for several hours. The results of this test should be checked against a master scale showing relationship between color and actual calibration. The lamp output energy should be at least 1 mw/cm2. An indication of energy less than this would usually show that the lamp was not operating correctly. The tested sample should be retained to check against tests done at approximately monthly intervals. Any major deviation in results should be reason enough to investigate further. Samples should be kept out of the light in a light-proof folder to maintain the usefulness of the results.
The above method does have a degree of variability, but is easily used and is of considerable value, especially if no other method is available or possible.

Radiometers
Other methods are used to determine the intensity of UV output, of which one of the most preferred is a device commonly known as a radiometer.
The radiometer is a low profile device that indicates digitally the intensity of UV energy when passed under a UV light source.
The units are a popular method of testing conveyor type units, as the results are obtained quickly. Different areas of the lamp can be checked if problems occur in curing. Obviously the unit is not useful when lamp arrays are built into the delivery of the press. In this case a similar device is used, though with a different configuration. A sensor or a fiber-optic cable is mounted in a position which can measure the lamp’s output. The cable is directed to a control and read-out console which shows the state of the lamp, either intermittently or continuously if so desired.
 

Gloss metering device
Maintaining gloss standards is particularly important when UV coatings are being used. This is especially true when presses are run for more than one shift. It is therefore of great benefit to have access to a device known as a “glossmeter”.
These meters usually have a standardized incidence angle set by accepted regulatory bodies at 60. There are five different incidence angles, but 60 is the most widely used and accepted angle, mainly because of its suitability to measure both gloss and matte finishes.
The operational use of most of these machines is straightforward after initial calibration is performed.
When a reading is taken on a sample, the unit directs a light beam at the fixed angle. Light is reflected from the surface of the sample and a receptor positioned to receive the reflected beam measures the intensity of the reflected light. The signal from the receptor is amplified and usually converted into a digital display giving the operator a visual value. 

Conclusion
The subjects covered in this section show that while some products were specifically made for UV, other items may be used for conventional and UV processes. However, it should never be assumed that all products for oil ink usage are suitable for use with UV. If there is any doubt as to the compatibility of a certain material or product, contact your supplier. Failure to use suitable products can only result in press downtime and substandard work.