You approve a proof, the job prints on the stock you chose, and the first thing you notice when the boxes arrive is that you can read page two through page one. The type is fine, the colour is fine, and the whole thing looks cheap because a shadow of the reverse side sits behind everything.
That is show-through, and it is decided by paper properties that rarely appear in a quote. Weight is the number everyone asks about. For double sided work, opacity and brightness matter at least as much.
Three properties, often confused
Weight, expressed in gsm, is mass per square metre. It correlates loosely with thickness and opacity, which is why people use it as a proxy for both. It is not the same as either.
Opacity measures how much light passes through the sheet, on a scale where 100 would be completely opaque. It is the property that determines show-through directly. Two papers at the same gsm can have meaningfully different opacity depending on how they are made and what fillers they contain.
Brightness measures how much light the surface reflects. High brightness papers look whiter and make colours appear more vivid, because there is more light bouncing back through the ink. It says nothing about show-through, and a very bright thin sheet can be the worst of both worlds.
There is also shade, which is the colour of the white itself. Papers marketed as bright white have a blue cast; natural or cream whites lean yellow. Shade changes how a printed image reads more than most people expect, particularly in skin tones.
Show-through versus strike-through
Two different faults get called the same thing.
Show-through is seeing the image from the other side because the sheet is not opaque enough. The ink stays where it should; the paper is simply translucent.
Strike-through is ink actually penetrating the sheet, which happens on very absorbent uncoated stocks with heavy ink coverage. The fix is different: less ink coverage, a different stock, or a different printing process.
Diagnosing which you have matters, because increasing the weight fixes show-through and may not fix strike-through.
What makes show-through worse
- Heavy ink coverage on one side. A full bleed dark photograph backed by light text is the worst case. The same paper carrying light text on both sides looks fine.
- High contrast between the two sides. Show-through is only visible when it interrupts something. Dark on dark hides it.
- Misaligned content. If the text on both sides lines up, the show-through falls behind your own type and is far less noticeable. Grids that align front and back help.
- Uncoated stock. Coatings add opacity and reduce absorption, which is why an uncoated sheet usually needs more weight than a coated one for the same result.
- Recycled content. Some recycled grades have lower opacity at the same weight, though this varies widely by make and is not a universal rule.
Practical starting points by job type
These are working figures, not rules, and the right answer depends on the specific paper and on how heavy your artwork is.
Double sided flyers and leaflets, moderate ink coverage: 130 to 170gsm silk or gloss usually sits comfortably. Below 115gsm, expect show-through on anything with a dark side.
Double sided flyers with a full bleed dark side: 170gsm and up, and consider a matt laminate on the dark side, which also stops it scuffing.
Booklet and brochure text pages: 100 to 150gsm depending on page count. Heavier text stock makes a thin booklet feel substantial and makes a thick one unwieldy.
Letterheads and documents: 100 to 120gsm uncoated is the conventional range, and opacity matters here because these get double sided printed later on an office machine.
Business cards and postcards: opacity is rarely an issue at 300gsm and up, so the choice is about feel and finish rather than show-through. Our guide to paper weight and gsm covers the feel side.
Brightness, and when it is the wrong goal
Bright white paper makes photographs pop and makes a design look crisp. It is the right choice for image heavy marketing material.
It is the wrong choice for anything read continuously. High brightness sheets increase contrast with black text, which is tiring over pages, and this is why book papers are cream or natural rather than brilliant white. If you are printing a report, a manual or anything with sustained reading, a slightly warmer, lower brightness stock is more comfortable and looks more considered.
Bright white also emphasises any inconsistency in your images. A photograph that looked acceptable on screen looks flat and grey on a very white sheet next to the paper margin.
Test rather than calculate
The reliable way to settle this is a dummy: the actual stock, at the actual weight, printed with your actual artwork, or at minimum a swatch held over a printed sheet. Opacity figures on a datasheet are measured under standard conditions and do not tell you how your specific dark blue behaves.
Ask your printer for paper samples and for a printed dummy on jobs where it matters. On a large run, the cost of a dummy is a rounding error against the cost of being wrong. Our note on proofs and colour profiles covers the related question of what a proof can and cannot tell you.
Choosing stock with us
Tell us the artwork is double sided and how heavy the coverage is, and we will recommend a stock rather than just quoting the weight you asked for. If your design has a dark full bleed side, we will say so at quoting stage and price the alternative, because that is the specification that most often disappoints on delivery.
We keep swatch books and can supply printed dummies on the actual stock before a run. Browse the stocks and finishes we carry under digital printing services, read our comparison of finishing options if a laminate is part of the answer, and request samples through our contact page.
Frequently asked questions
Does heavier paper always mean less show-through?
Generally but not reliably. Opacity depends on how the paper is made as well as its weight, so two 150gsm sheets from different mills can behave differently. Ask for the opacity figure or, better, test it.
Is coated or uncoated better for double sided work?
Coated stock is usually more opaque at the same weight and resists ink penetration, so it handles heavy coverage better. Uncoated is preferred where the piece will be written on or where the tactile quality matters, and then it needs more weight.
Can lamination fix show-through?
No. Lamination sits on the surface and does not change how much light passes through the sheet. It helps with scuffing and with the appearance of dark solids, which are different problems.
What is the cheapest way to reduce show-through?
Change the artwork rather than the paper: reduce the ink coverage on the heavy side, or align the content on both sides so the show-through falls behind your own elements. Both are free.
