My Jar Shipment Contains Visible Hairline Marks and I Cannot Tell Whether They Are Scratches or Cracks — Should I Use Those Containers for Candle Production?

The short answer: if you cannot rule out a crack, the jar is out

Hairline marks on new jars are usually one of two things. Most are scratches or scuffs, left when jars rub against each other or against packing material on the way to you. A few may be cracks, which run into the thickness of the glass rather than sitting on its surface. The two can look almost identical at arm's length, and the consequences are very different: a scratched jar is a cosmetic question, while a cracked jar can fail when a candle heats it.

So the goods-in rule is written the safe way round. A jar is used only when you are confident the mark is a surface scratch. If you are not confident, the jar is treated as cracked and removed from candle production. That rule does not need a test to confirm it, and it certainly does not need a burning candle to confirm it.

How to tell a scratch from a crack at the inspection bench

None of the checks below is perfect on its own, which is why you use them together. Clean the jar first: a smear of packing dust can hide a crack or make a scratch look deeper than it is.

Notice the cotton-pad row. Many people expect a crack to catch and a scratch to glide, but a tight crack can be completely smooth to touch while a deep scratch catches. That is why touch alone never clears a jar. The most telling sign is usually the light: turn the jar slowly against a bright light, and a crack often shows as a flash within the glass, while a scratch stays on the surface.

A third look-alike is worth knowing. Glass sometimes contains faint wavy streaks, known in the trade as cords, where the glass composition was not perfectly uniform. They look like soft lines or ripples inside the wall, have no sharp edge, and do not flash the way a crack does. Cords are usually cosmetic, but if a streak is sharp-edged, straight or starts at the rim, do not argue it into the cosmetic category; put it with the undetermined jars.

When two people inspect the same shipment, agree on one rule for disagreements: if either person thinks a mark could be a crack, the jar comes out. A second opinion is useful for confirming that a mark is a scratch; it should never be used to overrule someone who saw a possible crack.

Worked example: 300 clear jars, 14 with marks

Suppose 300 clear 200 ml salsa jars arrive, three packs of 100 at ₹2,950.00 each, which is ₹8,850.00 (3 × ₹2,950.00) and ₹29.50 per jar. Inspecting all 300, you find 14 with hairline marks. After cleaning and working through the checks, the results fall into three groups.

The undetermined three are the important lesson. They may well be harmless scratches. But the cost of treating them as cracks is ₹88.50 of glass, while the cost of being wrong the other way is a jar failing under a lit candle in a customer's home. That asymmetry is why the rule treats doubt as a crack.

The nine scuffed jars raise a separate question. They are safe, but a clear jar shows every mark. You might use them for products with a wraparound label, sell them as clearly described seconds, or return them if the finish matters for that product line. That is a cosmetic grading decision, and it is better made once at goods-in than argued over on the packing bench.

Working out where the marks came from

The pattern of marks usually tells you their origin, and knowing the origin tells you who can prevent it next time.

What to record and how to raise it

Record the invoice number, date received, carton numbers, the count in each group, photographs of each type of mark with the light angle that shows it best, and the condition of the packing. Keep one example of each group, labelled, until the supplier conversation is closed; keep the removed ones well away from good stock and wrapped as broken glass when you dispose of them.

For CSI jars, send your photographs and counts on WhatsApp (+91 7397976926). CSI does not publish acceptance limits or defect tolerances for glass, so a clear, photographed record is what makes the conversation productive. Apply the same rule to every supplier, including us: a jar you cannot clear of a crack never goes into a candle, whatever the invoice says.

Finally, re-check any jar that was accepted as scratched just before pouring. A scratch that has become a line with a flash inside it by the time it reaches the bench was either misjudged or damaged since, and either way it comes out.

Where this page fits

CSI already has guides that cover parts of this question. This page covers the goods-in check for the question above; these go deeper on the rest:

Three things to buy for this job

Frequently asked questions