Hash star grades are an informal way to describe melt quality and the amount of non-melting material. The common scale runs from one to six stars, with higher ratings claiming less non-melting material. They are not regulated laboratory certifications, and the same number can be applied differently by different producers.
Use the grade to start a conversation about the product's intended use. Don't let it end questions about batch identity, storage or testing.
One published version of the scale
Lowtemp's comparison of bubble hash and rosin gives a compact version. It puts cooking grade at one or two stars and half melt at three or four. Full melt sits at six, which Lowtemp describes as hash that melts completely when dabbed. Five stars gets no label in that summary.
That blank step is a small illustration of why the upper grades aren't consistently defined.
| Stars | Lowtemp's label | Question worth asking |
|---|---|---|
| 1–2 | Cooking grade | What use does the producer specify for this batch? |
| 3–4 | Half melt | How was the grade assessed? |
| 5 | Not assigned in Lowtemp's summary | What does this producer mean by five stars? |
| 6 | Full melt; “melts completely when dabbed” | Is this the producer's designation for this exact batch? |
The middle column is Lowtemp's wording, and the questions are ours. The table summarizes language, not a testing protocol. It doesn't certify a product or supply a recipe for using a lower grade in a device. Follow the hardware maker's compatibility guidance.
Microns are a separate measurement
A micron is a unit of length. On a hash label it commonly refers to a screen size or a collected fraction. Different cultivars have different resin-gland characteristics, and a screen can collect material of differing quality. There is no universal “best micron” that settles every batch.
Nor should wash-bag mesh and rosin-press filter mesh be treated as the same label claim. Ask which stage the number refers to. Reading rosin labels explains that ambiguity.
Color isn't a star test
Pale material can be visually attractive without proving melt quality. Wet hash in a collection bag has not yet shown how the finished dry product will behave. A darker shade can reflect material history rather than a simple good/bad ranking.
A reviewer should record the product, conditions and observed result instead of upgrading a visual impression into a certification. A shop should attribute a grade to its source rather than imply an independent test it did not perform.
Safety evidence lives elsewhere
California's testing requirements cover contaminants that a star rating cannot reveal. Match the certificate to the batch, and don't treat “full melt” as a synonym for contaminant-free.
The separate full-melt and six-star pages go deeper into those claims. A clear explanation of the rating is more useful than adding another star to the menu.