All paper starts off as uncoated. In the production process soft wood fibres are used to make a pulp that is then bleached, rolled flat, dried and smoothed. If viewed under a microscope you would see that the surface of the paper looks like a sponge with thousands of tiny holes. The most common uncoated paper is used by your home or office printer or photo copier.
Uncoated papers tend to feel rougher than coated papers and have a more tactile feel. You can however, get some very smooth uncoated papers and boards that have been repeatedly calendared to give a very flat, smooth surface whilst maintaining the porous properties of an uncoated paper or board. Uncoated papers tend to be whiter in appearance as well as feeling more bulky when compared to a coated sheet with the same GSM. Again as a result of the porosity of uncoated paper, they are much easier to write on as the ink from the pen is easily absorbed by the paper.
The litho printed results on uncoated paper are very different to coated papers. As the paper is more porous the ink is absorbed into the paper producing a very soft, muted affect where detail and sharpness can be lost. You could say that colours look flat or dull but this affect can be very appealing especially when used to promote a natural, earthy product. There is a stark difference however between the results you get from litho printing onto uncoated paper when compared to digital printing onto uncoated paper. Digital printing uses a toner that is then fused to the surface of the paper, it therefore does not get absorbed into the paper and hence gives a sharper, brighter image when compared to litho printing. This can sometimes be preferable as you get the sharp bright pictures of a coated paper along with the tactile feel of the uncoated paper.
There are many, many different types of uncoated paper and board but they can broadly be classified into the following groups:
Offset– the name given to uncoated paper used for general print work such as flyers, leaflets, brochures and loose leaf products.
Coloured– there are a vast array of coloured, uncoated papers to choose from including pastel and intense shades.
Bond– a paper used for everyday printed stationery and photo copiers
Wove– used for high quality stationery having a very smooth, uniform surface. These types of papers may carry a watermark such as Conqueror.
Laid– used for high quality stationery but this time with finely embossed, evenly spaced lines on the reverse of the paper giving a textured ribbed effect.
Linen– used for high quality stationery but with an embossed pattern that imitates the look and feel of linen cloth.
NCR– (No Carbon Required) – this is a specialist paper system with a coating on the surface of the paper that transfers the written image onto the paper below without the need for a carbon sheet. Many Business Documents use this paper eg. Order Pads, Invoice Pads and Receipt Books.
Recycled– uncoated papers made from pre used paper.
As mentioned, coated paper and board starts off life as uncoated. It is then coated, traditionally with a china clay liquid, that fills the tiny pours and crevices in the fibres of the base paper to give it a flat uniform surface. Different levels of rollers and smoothing blades are then used to create the different coated finishes of matt, silk or gloss. If you use your finger nail to rub a piece of matt coated paper it will go glossy! Different thicknesses of coating, create different grades of coated paper with the more expensive coated papers being called Triple Coated.
The coating process limits the amount of ink and moisture that the paper can absorb. It also makes it more opaque and resistant to wear and dirt and hence less liable to finger marking. The coating process also makes the paper less white in appearance when compared to uncoated paper with a more creamy appearance, although this isn’t noticeable unless held next to an uncoated sheet. This is only a general rule of thumb as there are many differences in the whiteness of both coated and uncoated paper. A final property of coated paper is that the same weight of coated paper can feel thinner than the corresponding uncoated paper as a result of the coated paper having been repeatedly smoothed, compressing the fibres together.
As coated papers are less absorbent, the litho ink sits more on the surface, giving a sharper more defined printed image which is often more desirable when you want sharp high definition pictures, photographs or text. Where there is a lot of text it is preferable to use a matt or silk paper as gloss paper can make it more difficult to read. The difference between the printed results from litho and digital printing are often indistinguishable when printed on a coated paper except that digital printing can often be more vibrant due to the larger colour gamut of the digital printing process.
Again there are many types of coated paper and board, broadly classified into the following groups:
Cast– a high gloss, mirror like surface, giving a shiny appearance on one side of the paper.
Gloss– smooth, glossy surface giving the paper or board a shiny appearance used predominantly for flyers,leaflets and brochures.
Silk– smooth, refined silky surface giving a soft sheen to the look of the paper again used for flyers, leaflets and brochures.
Matt– smooth, refined matt surface giving a matt appearance very similar to silk paper, used for flyers, leaflets and brochures.
Recycled– available in both gloss and matt – usually with at least 75% recycled content.
Single Sided Board– with a coating on one side and not on the reverse, these boards are traditionally used for Post Cards, Greetings Cards and Christmas Cards.
There are hundreds of different papers to chose from including papers made with cotton, eucalyptus and even Elephant Poo. Papers containing metallic flecks, transparent papers, onion skin papers, parchment papers, the list is endless. The two broad groups that I have described here however, make up the vast majority of the papers that we use on a day to day basis and are a good starting point into understanding Uncoated vs Coated papers and the differences between them. With regards as what paper or board to use, there are no hard and fast rules, its more a case of thinking about how the print is going to be used and what affect you want it to have.
Surface – Rough vs Smooth
Colour – White vs Off White
Bulk – High vs Low
Absorbency – High vs Low
Litho Image Sharpness – Low vs High
Digital Image Sharpness – High vs High
Litho Image Detail – Low vs High
Digital Image Detail – High vs High
Litho Print Results – Soft vs Bright
Digital Print Results – Bright vs Bright
Stationery – Yes vs No
Literature – Yes vs Yes