Insights › Defect glossary
9 November 2026
An inspection report that says "surface defects found" is not a report, it is an opinion. The difference between a supplier who can be held to a standard and one who cannot is usually just vocabulary: both sides naming the same physical fault the same way, with a limit attached to it.
These are the terms that come up on our own inspection sheets, in the order they appear on a moulded case. Each one has a cause, and most have a line where cosmetic becomes functional.
Thin fins of plastic forced into the parting line, ejector gaps or vent slots. Caused by insufficient clamping force, worn tooling or excessive injection pressure. On a phone case flash matters most at the camera opening and around the buttons, because that is where a finger goes. Limit: no flash on visible faces, and no flash that can be felt with a fingernail at the port cut-outs. Flash that has been trimmed by hand leaves a white edge on coloured parts and a rough edge on clear ones, so trimming is not a fix, it is a second defect.
Material that froze before filling the cavity, leaving a rounded or missing edge. Usually at the far end of flow, which on a thin case means a corner or the edge of a large camera cut-out. Functional: a short shot at a corner leaves a sharp gap that will catch on a pocket. Never accept a short shot on a structural edge, regardless of how small.
Shallow depressions on the outer face above a thick internal feature such as a rib or a boss. Caused by volumetric shrinkage as the core cools. Visible as a dull patch on gloss finishes and almost invisible on matte or textured ones. Cosmetic only; the limit depends entirely on surface finish, which is why finish has to be agreed before the tool is cut, not after.
A faint line where two flow fronts met and did not knit. Always present somewhere on a case with a camera hole, because the melt has to flow around it. Weak point mechanically as well as visually. The question is not whether a weld line exists but where it sits: a weld line across the back face is a rejection, a weld line hidden inside the camera lip is normal. Ask for the gate position on the tool drawing so you know where to expect it.
Silvery or dark streaks radiating from the gate, caused by moisture in the resin or by shear during injection. On clear and transparent-tinted cases this is the most common cosmetic rejection, because the streak scatters light and looks like a scratch. Drying the resin properly prevents it; once it is in the part, polishing will not remove it. Limit: zero on transparent parts, minor on opaque.
The case does not sit flat, or the two long edges bow inward. Caused by uneven cooling or by packing pressure differences. Functional, not cosmetic: a warped case lifts at a corner, collects dust and in extreme cases lets the phone click when pressed. Measure by laying the case on a surface plate and checking the maximum gap at any corner. Anything a fingernail can slide under is a rejection.
Small circular marks on the inside face where the pins pushed the part out. Usually invisible once the phone is in, so acceptance depends on whether the inside is visible in the packaging. A pin mark that has pushed through to the outer face is a sink mark and a rejection.
Print that lifts under tape. Tested with a cross-hatch cut and a specified adhesive tape pull, then judged against a reference photograph. This is the single most useful decoration test because it predicts field failure: print that passes the tape test rarely peels in a customer's hand, and print that fails it almost always does. Ask for the test method and the tape grade, not just the word "passed". The decoration comparison explains which processes are most at risk.
Colours out of alignment with each other or with the case edge. On multi-colour UV print, a shift of 0.1 mm is invisible on a logo but obvious on a thin outline or small text. Specify a registration tolerance and an inspection magnification; arguing about it after the fact with no number in the purchase order never ends well.
A dimpled surface on sprayed or painted finishes, caused by atomisation, solvent flash-off or substrate contamination. Reads as a texture rather than a defect on soft-touch coatings, and as a fault on high gloss. Judge against the approved golden sample under a defined light, not from memory.
Trapped air or a speck of dust between the film and the resin. Every bubble is also a stress riser that can delaminate later. Limit: zero visible bubbles over 0.3 mm on the visible face. Inspect with the case held at an angle to a light, because straight-on inspection hides all of them.
Measured as Delta E against the approved sample, not judged by eye, because two people under two lamps will disagree every time. The colour approval article covers how to set the limit and which instrument to insist on.
Microfiber or fabric lining separating at a corner. Invisible at inspection, obvious a month later. Functional in the sense that the customer sees it every time they remove the case. Test by a peel pull at the corner, and check the adhesive type; hot-melt that softens at 60 degrees will always lift in a car.
Ring off-centre or at the wrong depth, which on a magnetic case presents as slow charging rather than failure. Measure position, not appearance. Detailed limits are in the magnetic case build guide.
Sharp edges left by a dull punch or a worn tool at the port and camera openings. Cosmetic and functional at once: a burr catches on a cable and, on a hard PC case, can scratch a finger. Limit is usually defined by feel, which is unreliable, so define it by a radius in the drawing.
Put the defect names into the purchase order with an acceptance limit next to each one, and attach the approved golden sample as the reference for anything that is judged visually. Then a rejection becomes a comparison against a written limit rather than a negotiation. This is the same logic behind the AQL sampling plan: a defined sample size and a defined defect class turn a subjective argument into arithmetic.
Two practical notes. First, separate critical, major and minor before the order ships, because most suppliers will happily agree that something is a defect and then argue it is a minor one. Second, keep a photographed reference set of every defect class from the golden sample run, so that a new inspector in either factory judges the same way.
Our inspection sheets list these classes with limits and photographs, and every batch ships with the report. If you already have a defect list from your own QC, send it and we will map it to ours before the first production run rather than after.
Two multi-layer designs, where most of the defects above show up first: Aegis Clear Dual-Layer for iPhone 18 Pro Max and Aegis Clear Dual-Layer Magnetic for Galaxy S26 Ultra.
Request a quote
Tell us the models, the quantity and where it ships. You get a unit price at your quantity tier, the tooling you are buying into, and the cost to your door — no obligation.