Fifty One-Kilo Orders: Holding Batch Consistency Across a Season

Fifty orders of one kilo, placed over eleven weeks by the same client, filled from five production batches and one change of raw material supplier. Three of those kilos behaved differently from the rest, and the client noticed on the third week of a window campaign when a re-order did not match the first installation.

Small orders are where consistency breaks down. A single 25 kg sack is internally consistent by definition. Fifty separate kilos, packed on different days from different blends, are not, and the differences that matter are invisible until the material is hydrated and lit.

What actually varies

Three properties drift between batches, and each has a visible consequence:

• Absorption capacity. A 5 percent shift in cross-link density changes how much water a kilo will take. Mix the same ratio and one batch comes out at 300 g/L, another at 325. Under raking light the difference reads as a tonal step.
• Particle size distribution. More fines means a denser-packed, whiter-looking snow that hydrates faster and dries harder. Fewer fines means a coarser, more translucent finish.
• Residual moisture in the dry powder. Powder stored in a humid room picks up 2 to 4 percent water. That is enough to make it clump in the bag and to shorten the working life of the mixed batch.

None of these is a defect. All of them are reasons to keep records.

The numbers to log, and why

For every batch you receive, record four things and keep the sheet with the delivery note:

The absorption test takes ten minutes and is the single most useful thing you can do. Ten grams of powder in 500 ml of water, stirred, left 20 minutes, poured through a sieve and weighed. The result tells you whether to mix this lot at 22 or at 26 litres per kilo. Without it you are guessing, and the guess shows up in the finished display.

The counter-intuitive finding

Mixing to a fixed water ratio across a season produces more variation than mixing to a fixed finished density. Everyone does the first because it is written on the bag. But the ratio is only correct for the batch the supplier tested, and a 5 percent absorption drift turns a consistent recipe into an inconsistent product.

The fix is to mix by feel and verify by weight: hydrate to a target of 300 g/L, checking with a jug and scale, and adjust water per batch rather than following the ratio blindly. Crews who switch to this report far fewer “this batch looks different” conversations, because the thing being held constant is the thing the client actually sees.

Packing fifty kilos properly

If you are supplying small orders across a campaign, pack them all before the campaign starts, from one blend, into foil-lined bags with a desiccant sachet, and label each with the lot and the packing date. Fifty one-kilo bags from one 25 kg sack, packed on one day, will match each other perfectly for six months. Fifty bags packed as orders arrive will not.

Cost: a few hours of packing labour and a box of bags. Saving: the re-install you would otherwise do in week three.

A window campaign that stumbled

A retail chain ordered snow in weekly instalments for a rolling window programme across 20 stores. Store 4 installed in week one and store 11 installed in week six from a later batch. The two windows sat 30 metres apart on the same street, and the difference was obvious: one looked crisp and blue-white, the other slightly cream and flatter.

The supplier had not changed specification. The second batch had a higher fines fraction, which hydrated faster and packed denser. Nobody had retained a sample, so the argument ran for two weeks before the material was replaced at the supplier’s cost to end it.

A 100 g retained sample and a completed absorption record would have ended it in ten minutes and pointed straight at the mix ratio rather than the material.

For campaigns, specify by lot, hold samples, and adjust water to hit density rather than following a fixed ratio. The grade data sheets give the absorption ranges you are working within.