2.5D, 3D, UV and privacy glass — which to stock and when
A plain explanation of the tempered glass types you'll be offered, what each is actually for, and where each one causes problems.
4 min read
Supplier catalogues throw a lot of labels at you: 2.5D, 3D, full glue, edge glue, UV, matte, privacy, anti-blue. Some of these describe the shape, some describe the adhesive, and some describe a coating. They're not alternatives to each other, which is why the terminology is confusing.
Here's how the categories actually break down.
Shape: 2.5D vs 3D
2.5D is flat glass with rounded edges. The face is a single plane; only the very perimeter is bevelled, so it feels smooth under a thumb instead of sharp. This is what fits the vast majority of phones, because most phones have flat panels.
3D (sometimes "curved" or "edge to edge") is glass that is genuinely curved to follow a display that bends over the sides of the phone. It's a harder part to make and a harder part to fit.
Getting this wrong is not subtle. Flat glass on a curved screen touches in the middle and lifts at the edges, leaving a visible rainbow band and an edge that catches on everything. Curved glass on a flat screen rocks and won't bond at all.
Adhesive: edge glue vs full glue
Edge glue has adhesive only around the perimeter, with a dry zone in the middle. It's cheaper, easier to apply, and forgiving of small dust particles because the centre never bonds. The downside is a slightly hollow feel and the risk of the centre separating over time.
Full glue (also "full adhesive") is coated across the entire back face. It bonds completely, feels like part of the screen, and generally improves touch response at the edges. It's also far less forgiving: a single dust speck under the centre becomes a permanent visible blemish, and it cannot be repositioned once it touches down.
On a curved screen, full glue is usually the only thing that works — edge glue has nothing to grip in the curved region.
UV glass
UV glass ships with a liquid adhesive and a small UV lamp. You apply the liquid, lay the glass, and cure it. Done correctly, it gives the best optical result on curved panels and bonds right to the edges.
Done incorrectly, it is the most expensive mistake on this list. The liquid can wick into the earpiece, the charging port, or under the frame, and in the worst case it reaches the display connector. Fingerprint readers are particularly sensitive — excess adhesive over an optical sensor can stop it reading.
Stock it if you fit curved-screen flagships regularly. Don't make it your default.
Coatings
These stack on top of any of the above:
- Anti-glare / matte. Diffuses reflections and hides fingerprints. Costs some sharpness; text looks slightly softer. Popular with outdoor workers.
- Privacy. A louvre layer that darkens the image off-axis. It cuts brightness noticeably head-on too, and customers often dislike it once they see it. Warn them before fitting.
- Anti-blue. Filters part of the blue spectrum, usually giving the screen a faint yellow cast. Sold on eye-comfort claims. Manage expectations rather than overselling it.
Thickness and hardness
Most protectors are quoted around 0.3 mm and marketed as "9H". Treat the hardness figure with scepticism — it refers to a pencil-hardness scale and is used loosely across the industry. Thickness is more meaningful: thicker glass survives more, but sits higher in the case cutout and can interfere with a tight case.
What to actually stock
For a general repair counter:
- 2.5D full glue as the default. It covers most phones and most customers.
- 2.5D edge glue as a budget option and for phones where you expect dust trouble.
- 3D full glue for the curved models you see regularly.
- UV only if curved flagships are a real part of your work.
- A small number of matte and privacy pieces in your most common sizes, on request rather than on display.
The part still has to fit
None of these categories affects compatibility. A 2.5D full-glue protector and a matte edge-glue protector for the same phone are the same shape — they belong to the same part group. Type is a choice you make after you've established which part fits.
Look up the model first, get the part code, then decide which variety of that part the customer wants.