Stone and tile are attractive substrates for UV printing because they are dense, durable and visually premium, and they are difficult substrates because they vary. Two granites from the same quarry can print differently, and a polished marble face behaves nothing like a cleft slate one. On stone, the qualification work matters more than the machine choice.

This guide covers how to qualify a porcelain, granite or marble surface before production: identifying the material and its finish, understanding what porosity does to the print, planning white ink on dark stone, checking thickness and weight against the platform limits, handling the finished piece, testing the sample, and keeping a repeat run consistent.

Why is stone a family rather than one setting?

Because slate, granite and marble behave differently.

The published guidance for this range is that stone varies in porosity, cleft, polish, sealers and dust retention, and that a single setting will not suit every material sold as stone.

Each of those variables changes the print. Porosity controls how much ink the surface absorbs. Cleft gives the surface a direction that can affect edge definition. Polish changes how the ink sits and how the result reflects light. A sealer changes the surface energy entirely, and an unsealed stone may draw the ink into the face rather than holding it. The published qualification route for stone asks for the type, supplier, finish, porosity, cleft or polish, sealer, colour and batch to be recorded before anything is printed.

Tile adds its own split. A ceramic or porcelain tile may be glazed, unglazed or coated, and each condition responds differently to UV ink. The published tile guidance therefore asks for the tile to be identified as ceramic or porcelain and as glazed, unglazed or coated, with the supplier, batch, dimensions, thickness and weight recorded alongside.

How should a stone or tile surface be qualified?

Record type, finish, porosity and batch first.

Qualification starts with a cleaned and conditioned representative piece, tested on the actual printable face rather than on a lab sample of the same name.

The published route is specific about the order. Identify the printable face and record the stone type, supplier, finish, porosity, cleft or polish, sealer, colour and batch. Remove dust, oil, cleaner residue and protective-film adhesive. Evaluate only an approved primer or pretreatment when one is genuinely needed. Then test colour, white opacity, adhesion, scratching, cleaning and the exposure conditions relevant to the final installation.

On a tile the same sequence applies with one addition, which is that the tile should be identified as ceramic or porcelain before the test, because the two materials have different absorption behaviour. The published tile guidance notes that glazed, unglazed and coated tiles can respond differently to UV ink, so the finish is part of the identification rather than a detail.

What does porosity do to the print?

It decides how much ink the surface absorbs.

A porous or cleft face can draw ink away from the intended edge, while a polished or glazed face holds it, so the two conditions need different preparation and different expectations.

Porosity is measurable rather than a matter of opinion. The standard test for water absorption of ceramic tiles (ASTM C373) exists precisely because absorption is a material property that affects finishing and service. The practical consequence for printing is that absorption changes the white layer. A surface that wicks will show a thinner, less even white than a sealed or polished one, and the answer is usually a change of preparation or an approved sealer rather than more passes.

Dust is the second half of the problem. Stone cutting and finishing produce fine dust that sits in the cleft and dulls the bond, and the published guidance asks for dust, oil, cleaner residue and protective-film adhesive to be removed as part of qualification. A cleaning method that is standardised and recorded is worth more on stone than on almost any other substrate, because the surface varies from piece to piece and the cleaning is what makes the pieces comparable.

How should white ink be planned on dark stone?

As a controlled layer over an approved white.

On dark granite or slate, the white layer is what makes the colour visible, so its coverage is a design decision rather than a printing default.

The published stone guidance asks for direct colour and white-underbase options to be compared on the actual printable face. The reason is that a dark, porous stone will show the white layer through the colour unevenly if the white is thin, and a sealed stone will show it sharply. Comparing the options on the real material is the only way to choose the construction that suits the piece.

Viewing conditions belong in the same decision. A white-backed print on a polished stone reads differently from the same print on a matte one, and the published ceramic guidance lists white ink opacity among the checks a tile sample must pass. Where the piece will be seen in a particular light, that light is the condition in which the sample should be approved.

What do thickness and weight change?

The loading and support limits for the bed.

Stone is dense, so a modest panel can approach the published media weight limits, and thickness and weight are recorded before a part is loaded.

The published figures set the boundary. The wide-format platforms in this range are published at 1 to 100 millimetres of media thickness and 50 kilograms per square metre, while the compact AJ1206 is published at 0 to 35 millimetres and a maximum media weight of 36 kilograms. A stone panel that fits the print area can still fail on mass, and a thick slab can fail on head clearance, which is why the three limits are read together.

Support is the third consideration. A heavy or uneven panel needs the bed to hold it flat, and the published qualification for larger stone work notes that handling equipment, bed support and operator access have to justify the workflow before a larger platform is chosen. Where the panel is thin and fragile rather than thick and heavy, the risk reverses: the piece flexes under handling, so the loading plan has to protect it rather than simply support its weight.

How should the finished piece be handled?

As a fragile surface, not a flat board.

Across this range the published approach is to protect the printed surface through unloading, handling and packing, and stone raises the stakes because the piece is heavy as well as finished.

The published canvas and panel guidance is the model: the sample should be handled through the same sequence planned for production, so that the handling itself is tested rather than assumed. For stone that means unloading with the right support, stacking with protection between pieces, and packing so that the printed face does not rub against another part in transit.

Cleaning is the other half of handling. The finished piece will be cleaned in service, and the published sample test asks for cleaning to be included in the approval. A print that survives the intended cleaning method is a finished product; a print that looks perfect and then dulls under the customer’s usual cleaner is a return waiting to happen.

What should the sample test cover?

Adhesion, white opacity, colour and exposure.

The published guidance is to approve the sample against its real handling, cleaning, moisture and indoor or outdoor exposure requirements rather than against appearance alone.

The exposure test is the one that separates an indoor sign from an outdoor plaque. A stone piece installed outdoors sees rain, frost and ultraviolet light, and the published stone guidance asks for the sample to be approved against the exposure the finished piece will actually face. Where the print will be exposed to weather, the accelerated weathering test is the practical way to compare constructions before installation rather than after a season of failure.

How do you keep a repeat run consistent?

By fixing the material source and the recipe.

A repeat stone job is reproduced from the material batch and the recorded process, because a change of quarry lot or sealer changes the result more than a change of setting does.

The published process record for this range covers the approved artwork version, the RIP and ink-layer settings, the substrate and pretreatment, the fixture or loading method, the bed position, the environmental conditions and the inspection result. For stone, the material fields carry the most weight, so the supplier, finish, sealer and batch are the entries that make the second order match the first.

Two habits support that. Standardise and record the cleaning method, because it is the step most likely to be done differently by a different operator. And keep the approved sample with its record, so a later order is checked against the same physical piece rather than against a photograph. The chemical and material obligations for the inks and any pretreatment follow the applicable regulations (REACH), and process practice for industrial print is published by the industry bodies in the field (PRINTING United Alliance).

What the decision comes down to

Printing on porcelain, granite or marble is a material qualification job. Record the type, finish, porosity, sealer and batch, decide the white construction on the real face, confirm the thickness and weight against the platform limits, and approve the sample against the exposure it will meet.

The published stone and tile qualifications for this range sit with the stone and slate collection and the ceramic tiles collection, the platform limits that govern loading are set out on the AJ2513G/R page, and the tile workflow is covered in the guide to UV printing on ceramic tiles.