A pattern behind glass. Until it can't be.
Glass painters have transferred designs the same honest way for a long time: tape the paper pattern to the back of a clear pane and trace the lines through it, or slip carbon paper underneath. For flat, clear glass that trick is hard to beat, and this page will not pretend otherwise. But it depends on light passing through and the pane lying flat — so it fails on opaque, dark, or coloured glass, on mirror, on a pane already fixed in a window, and whenever you want to resize the design freely. That is where Grid Maker Pro helps: plan the composition for free in the browser with all 82 overlays, then use the AR app to anchor your pattern to the front of the glass through the phone and trace it at the size you choose. Free grids for the thinking. The paid app for the panes the pattern-behind trick can't reach.
When the pattern-behind trick runs out.
A design drawn on paper has to land accurately on the pane before any pigment fires or any came is cut, because glass is unforgiving of a wandering line. For clear glass the taped pattern is genuinely the simplest tool there is — cheap, exact, and never in need of charging. The trouble is the conditions it quietly assumes. Here is the honest shape of when it works and when it doesn't, and the third route the AR app adds for the panes it can't handle.
Pattern behind glass, and its limits
It is often the right answer. It just needs a very particular pane.
- Clear and flat: the light has to pass through so you can see the pattern from the front, and the surface has to sit flat against the paper. That is the ideal case — use it.
- Opaque, dark, mirrored, or coloured glass blocks the light the trick lives on. You cannot see a pattern taped to the far side of it at all.
- Already installed panes — a fixed window, a leaded panel in a frame — leave no reachable back to tape a pattern to.
- Resizing means re-drawing or re-printing: a paper cartoon is locked at the size it came out of the printer.
Anchor the pattern to the front of the pane
The Grid Maker Pro AR app pins your pattern photo to the glass through the phone camera, from the front.
- It does not need light through the pane. Look at the screen and the design sits on the surface, so opaque and coloured glass are no obstacle.
- It works on installed and vertical panes — a fixed window, a panel in its frame — where there is no back to reach.
- Set the size on screen and fit one design to a taller or wider pane without re-printing the cartoon.
- It runs on-device. Your pattern photo never leaves the phone — the same privacy promise as the web tool.
Plan free. Trace onto the glass.
A painted or leaded pane is committed once fired or cut, so the order matters: settle the design small where mistakes are free, then transfer it to the surface. The free browser tool owns the first half; the AR app owns the second — and if your glass is clear and flat, a pattern taped behind it does the second half just as well. Three moves.
Compose in the browser
Drop your reference into the free tool and stack composition overlays. Settle the focal element, the borders, and the major shapes while changes cost nothing.
Free web tool · all 82 grids
Anchor it to the pane
Open the AR app at the glass, point the phone, and pin the pattern to the surface. It locks in place at the size you set — no light-through, no reachable back needed.
AR app · paid
Trace it by hand
Draw the lines you see through the screen straight onto the glass with a marker or paint. The design is already at the size you chose, so the pane time goes into painting, not measuring.
Marker · glass paint · your hand
Free overlays that settle the design.
A leaded panel reads as a whole from across a room, and the lead lines carry as much of the design as the colour does — so the large-scale structure has to be deliberate before any glass is cut. These overlays live in the free browser tool. Stack them over your reference, resolve the composition, and only then take it to the pane. Leon Battista Alberti described squaring a design through a gridded veil in 1435;1 the principle behind transferring a small picture up accurately has not changed, only the tools have.
Rule of thirds
The first decision. Seat the focal element on a third intersection so a panel reads at a glance from across the room.
→Golden ratio
Phi proportion and the spiral for balancing several glass shapes and lead lines across a tall pane.
→Dynamic symmetry
Root-rectangle diagonals tie the borders and came lines of a window to the shape of the pane itself.
The AR app does the thing a taped pattern can't.
The web tool plans. The app executes on the panes the pattern-behind trick can't reach. Built by Sujith Puthran, a working artist of more than fifteen years, the AR app locks a pattern photo over your real pane and lets you trace at the size you set, on-device. The 82 composition grids stay free forever in the browser — the app is the separate, paid product for the surface itself, and it never paywalls the planning.
Grid Maker Pro AR
Anchor any pattern to your pane and trace it by hand at the size you choose — no light-through, no reachable back, no re-printing to resize. Android on Google Play, with iOS planned. No account to start, and your pattern photo never leaves the device. The free tier gives you three AR traces of your own photo every month plus all 82 overlays, so you can test it on a real pane before paying.
Free tier 3 AR traces / month + 82 overlays · Paid $29.99/yr · $6.99/mo · $79 lifetime
What glass painters reach it for.
For clear glass I still tape the cartoon behind it — nothing is faster. The AR app earns its place on the dark and opaque pieces, where a pattern behind the pane is simply invisible. I plan the whole layout on the laptop with the thirds overlay, then pin the design to the front of the glass through the phone and paint the trace lines straight onto the surface.
Half my work is on panes already fixed in a frame, so there is no back to tape anything to. Anchoring the reference to the front of the installed pane and matching lines in place is far cleaner than propping mirrors and prints. Resizing the design on screen to fit a slightly different opening has saved me a print-shop trip more than once.
The questions glass painters ask.
How do I transfer a design onto glass?
For flat, clear glass, the simplest method is still the oldest: tape the paper pattern to the back of the pane and trace the lines through the glass, or slide carbon paper between the pattern and the surface. It costs nothing and never drifts. That trick only works when light passes through and the pane lies flat. When the glass is opaque, coloured, mirrored, already installed vertically, or when you need to resize the design freely, the pattern-behind method fails — and that is where the Grid Maker Pro AR app helps. It anchors your pattern photo to the pane through the phone camera so the design sits locked on the surface at the size you set, and you trace what you see by hand. The step-by-step of both routes is in how to trace onto glass.
How do I trace a pattern onto opaque or coloured glass?
Opaque, dark, or heavily coloured glass blocks the light the pattern-behind trick depends on — you cannot see a paper pattern taped to the far side. The Grid Maker Pro AR app does not rely on light passing through: it pins your pattern photo to the front of the pane through the phone camera. Look through the screen and the design sits on the glass at full size, so you draw the lines with a marker or paint straight onto the opaque surface. It also handles mirrored glass and panes that are already fixed in a frame or window, where you cannot reach behind them at all.
Should I plan the composition before I paint on glass?
Yes, and that part is free. Glass painting is unforgiving — a fired line is permanent and a lead came follows the drawn cartoon exactly — so the layout has to be settled before pigment touches the pane. Use the free browser tool to drop the rule of thirds, golden ratio, or a dynamic-symmetry overlay over your reference and resolve where the focal element, the borders, and the major shapes sit. Only once the small design holds do you scale it to the glass. Composition is planning; the AR app is execution.
Can I resize a stained glass pattern to fit a different pane?
This is one place AR earns its keep. A paper pattern is fixed at the size it was printed; scaling it to a new pane means re-drawing it or a trip to a copy shop. In the AR app you set the size of the pattern on the pane by eye through the phone, so a design drawn for one window can be fitted to a taller or wider one without re-printing. For a precise printed cartoon at a fixed scale you may still want the paper route, but for fitting a design freely to the glass in front of you, resizing on screen is faster.
Is the Grid Maker Pro AR app free?
The free web tool with all 82 composition grids is free forever, in any browser, with no signup. The AR app is the separate paid product that locks a pattern over your real pane and lets you trace at full scale — the thing a browser cannot do, and the thing the pattern-behind trick cannot do on opaque or installed glass. Its free tier gives you three AR traces of your own photo each month plus all 82 overlays. Unlimited AR is $29.99 a year, $6.99 a month, or $79 once for lifetime access. It runs on Android via Google Play, with iOS planned, and starts with no account.
References
- Alberti, Leon Battista. On Painting (Della Pittura, 1435). Penguin Classics (1991). ISBN 978-0-14-043331-3. The velo — the gridded veil for squaring a design up accurately.
- Roberts, Melissa J. Empress of Dirt — image transfer methods. empressofdirt.net. Practical survey of tracing and carbon-transfer techniques for craft surfaces, including glass.
- Hambidge, Jay. The Elements of Dynamic Symmetry. Yale University Press (1920). Dover reprint, ISBN 0-486-21776-0. Root-rectangle composition keyed to the proportions of the surface.
- Bouleau, Charles. The Painter’s Secret Geometry. Harcourt, Brace & World (1963). The canonical study of compositional armatures and proportion in painting.
Get a pattern onto any pane.
Compose the design for free in the browser with all 82 overlays, then anchor the pattern to the pane with the AR app and trace at the size you set. For clear flat glass a taped pattern still wins; for opaque, coloured, or installed panes, AR reaches what it can't — and your pattern stays on your device.