Art prints and paper: how a portrait print is made, sized and kept

An art print turns a digital image into an object you can hold and hang. Between the file and the wall sit a series of choices: the printer and its ink, the paper and its coating, the number of pixels, the shape of the sheet, the colour settings, and how the print is kept before it is framed. This guide explains each of those choices in plain words, with the sources behind every fact, so you can judge a print you order or make one from a digital download. Ten pages explain each topic in more detail, and this page shows how they connect.

Why this matters for a pet portrait

Purrealism offers each royal pet portrait in two editions: a digital download, or an art print in one of four sizes, 8 × 10, 12 × 16, 18 × 24 or 24 × 36 inches, on matte or glossy paper. If you order the art print, you choose the size and the paper finish in the portrait studio. If you choose the download, every other decision on this page becomes yours.

Either way, the same facts apply. A portrait of a pet is often meant to stay on a wall for many years, and sometimes it marks a pet who has died. How long its colours last, how sharp its details print and how well it survives the weeks before framing all depend on choices that are easy to get right once you know what they are.

How an art print is made, step by step

The printer

Most art prints today are inkjet prints. The Image Permanence Institute at Rochester Institute of Technology, which studies how prints and photographs age, dates the first device that printed with drops of ink from a nozzle to 1867, when Lord Kelvin built one to record telegraph messages. Its timeline continues with the first desktop inkjet printers from Hewlett Packard in 1984, colour desktop inkjet in 1987, wide format inkjet in 1993 and full-colour pigment inkjet in 2000.

The Historic New Orleans Collection, a museum and research centre, says the French word giclée, meaning a splash or spurt, was first used for inkjet art prints in 1991, for images from the Iris printer introduced in 1985. The word now means inkjet or pigment printing in general. The Image Permanence Institute lists giclée as a term often used for marketing, and prefers the plain word inkjet. The page on giclée printing and how inkjet printers work explains the machines, the two kinds of print head and the history of the word.

The ink

Inkjet colour comes as dye, which dissolves in the ink liquid, or pigment, which stays as tiny solid particles. The Image Permanence Institute says pigment colours have tended to resist moisture, air pollution and light better, while dyes have lasted better during handling. The University of Illinois Library's preservation guide adds that dye inks cost less, which is why most home and office printers use them, and that pigment prints on good paper may last more than 100 years before any fading.

The paper and its coating

Plain paper soaks up inkjet ink, so colours look dull and lines blur. The Image Permanence Institute says paper makers add a thin top coating, which it calls an image receiver layer, to keep the ink near the surface. The coating sits on a base sheet, and that sheet has its own chemistry. The Library of Congress says permanent paper, as defined by the US standard ANSI/NISO Z39.48, has a pH of 7.5 to 10.0, at least 2% alkaline reserve and less than 1% lignin, the natural wood substance that yellows paper. The page on archival paper and inks explains these labels and how ink and paper age together.

The pixels

A digital image is a grid of pixels, and a print spreads them across the paper. The number that lands on each inch is the pixels per inch. The University of Chicago Press gives 300 as its standard print resolution for photographs, and SUNY Broome's library accepts 150 to 300 per inch for large posters. The page on print resolution in pixels per inch shows how to work it out for any file.

The shape

Each print size has a shape, and a photo of another shape must be trimmed at two edges to fill the paper, or printed with blank borders. The page on print sizes, aspect ratios and trimming shows how much each common photo shape loses at each size, and compares the inch sizes with the ISO A sizes used in most countries.

The colour

A screen mixes red, green and blue light, while a printer mixes inks. Colour spaces and profiles let the two agree on what the numbers in a file mean. The International Color Consortium, which writes the specification for colour profiles, says many printers accept only RGB data, so sending them CMYK can give a worse result. The page on colour spaces for printing explains sRGB, Adobe RGB, CMYK and soft proofing.

Drying, storage and time

A fresh print needs to dry, then to be kept flat, clean and covered until it is framed. Over the years, light and air can fade it. The pages on lightfastness and fading and storing unframed prints cover how fading is measured and how to protect a print before it goes into a frame.

Core ideas in one place

A few ideas appear on every page of this guide.

Name the print by its parts. The Image Permanence Institute recommends describing a print by colorant, process, coating and support, in that order. Its example, "pigment inkjet on porous-coated baryta paper", tells you more about how the print will age than any brand name or the word giclée.

Surface and coating go together. The coating under a glossy or matte surface decides how the ink sits. The Institute says swelling polymer coatings can be made the glossiest and protect the ink from scuffs and air pollution, but work with dye inks only, while porous coatings take both inks and dry at once. The page on matte and glossy paper compares the surfaces.

Weight is a measure of mass. Paper weight in grams per square metre tells you how heavy a sheet is for its size. Markus Kuhn's guide to paper sizes at the University of Cambridge explains that the North American pound system weighs 500 sheets of a basic size that changes with the grade, so the same pound figure can mean different papers. The page on paper weight, gsm and thickness converts between the two systems using the US Government Publishing Office's basic sizes.

Damage adds up. The Canadian Conservation Institute says light damage depends on the total dose, light level multiplied by time, and that faded colours cannot be recovered.

Ink and paper combinations compared

The ink and the coating work as a pair. This table brings together what the Image Permanence Institute, the University of Illinois Library and the American Institute for Conservation report about the three common inkjet combinations.

The Canadian Conservation Institute gives times for fading. It sorts coloured materials by the ISO Blue Wool scale, a set of dyed wool cloths from the 1920s in which each cloth is 2 to 3 times as sensitive to light as the next. Under 50 lux, a highly sensitive colour shows a just noticeable fade in 1.5 to 20 years, and a colour of low sensitivity in 300 to 7,000 years. Where a given print falls on that scale depends on its ink and paper, so ask about both before you buy or print, because the word giclée on a label names only the printing method.

The four sizes compared

This table puts the main numbers for the four Purrealism print sizes side by side. The pixel figures multiply each side by 300 and by 150. The last two columns show a photo of 3,024 × 4,032 pixels, a 3:4 shape, fitted to each size.

The print resolution calculator further down this page does the same work for any image. You type a pixel width and height, or let it read them from a photo you choose. For each of the four sizes, it turns the print to match the photo, trims the photo at two opposite edges to match the print's shape, and shows the pixels per inch after the trim, the band that figure falls in (300 or more, 150 to 299, or under 150) and the percent of the photo trimmed. For the sizes in centimetres and where each suits a room, read how big is an 8 × 10 print.

Common mistakes

Each of these mistakes is named in a source behind this guide, and each one is easy to avoid.

1. Printing from a copy saved from a website. Rollins College's library says web images are usually saved at low resolution for screens and are unsuitable for printing. Use the original file.
2. Enlarging a small file. The University of Chicago Press says upsizing an image to add resolution does not produce usable results.
3. Re-saving a JPG before printing. The same press says JPGs lose image data each time they are saved. Edit in a lossless format and export once.
4. Printing a photo on plain office paper. The Image Permanence Institute says plain paper dulls colour and line quality. Use a coated photo or art paper.
5. Sending CMYK to an RGB printer. The International Color Consortium says many printers accept only RGB data and convert CMYK back, which can give a worse result.
6. Comparing papers by pounds across grades. Kuhn's guide shows that the pound figure depends on the basic sheet size, so compare papers in g/m².
7. Stacking or rolling inkjet prints. The Image Permanence Institute advises against both, because contact and bending scuff and crack the surface.
8. Storing a print in a PVC sleeve or taping it. The Institute says PVC should never be used with imaging materials, and that pressure-sensitive tape can cause deep yellowing within months.
9. Leaving a dye print in damp air. The Institute says dye inkjet prints above 80% relative humidity can bleed in less than 24 hours.

Choosing a portrait print on this site

Start with the portrait itself. The gallery shows finished portraits, and the article on how to choose a royal portrait style for your pet helps with the style. The Patiala Royal portrait on this page, a Pomeranian in a blue coat and jewelled turban on a red throne, carries fine detail in its jewelled turban, and detail like that is what to check closely on a test print.

Then choose the edition. With the art print, pick the size by where it will hang and the finish by the light in the room. With the download, check the file's pixels and shape against the table above, follow the steps on printing a digital download at home or at a print shop, and make a small test print before a large one.

Last, plan for the time before framing. Keep the print flat in a sleeve or folder, carry it on a board and frame it soon. The guide to framing and hanging continues from there, with frames, mats, glazing and where to hang the portrait. If the portrait is a present, the guide to pet portrait gifts covers the occasion.