Nine out of ten DTG complaints are pretreat, not printing. The printer is usually doing exactly what it was told. The variable is the chemistry underneath.
1. Dull, grey or thin white
Cause: too little pretreat, or not dried properly.
Fix: increase the applied quantity and confirm by weight. Then press longer or hotter until the panel is genuinely dry and flat. Weighing is the important part; "looks about right" is how this drifts week to week.
2. Visible box or halo around the print
Cause: the pretreated area is bigger than the print, or its edge is hard.
Fix: spray only slightly beyond the print, feather the edge rather than stopping abruptly, and press the whole panel so any sheen change is consistent across it.
3. Patchy white, blotchy coverage
Cause: uneven application, a partially blocked sprayer nozzle, or an uneven press platen.
Fix: clean and test the nozzle onto paper, check the spray pattern, and check platen contact across the whole area. Worn platen foam causes pressure differences that look exactly like a chemistry fault.
4. Print washes off or fades badly after one wash
Cause: under-cure. The ink and pretreat never fully bonded.
Fix: verify actual temperature at the garment with a probe or temperature strip, not the machine's display, and extend the cure. Then wash-test a sample before shipping, as in the QC checklist.
5. Stiff, plasticky hand
Cause: too much pretreat, too much white, or double-curing.
Fix: reduce pretreat to the measured minimum that still gives a clean white, reduce white underbase density in the software, and cure once properly rather than twice partially.
6. Pretreat marks on the garment away from the print
Cause: overspray, drips, or handling with pretreat-contaminated gloves and platens.
Fix: contain the spray area, wipe the platen between garments, and keep pretreated garments away from finished ones. Contaminated platens transfer marks all day before anyone notices.
7. Poor results on a specific garment
Cause: fibre content or a garment finish. Polyester blends, bamboo, viscose and heavily softened or water-repellent finishes all behave differently from combed ring-spun cotton.
Fix: test every new blank before promising it, and keep a list of blanks that work. See choosing blanks.
8. Inconsistent results between mornings and afternoons
Cause: ambient humidity and temperature, and press recovery time.
Fix: let the press reach temperature between garments rather than working faster than it recovers, and note humidity if your results swing seasonally. Shops in humid climates often need longer drying.
The reference table
| Symptom | First suspect | Second suspect |
|---|---|---|
| Dull white | Too little pretreat | Under-dried |
| Visible box | Over-sprayed area | Hard edge, partial pressing |
| Patchy white | Nozzle or spray pattern | Platen contact |
| Washes off | Under-cure | Pretreat and ink mismatch |
| Stiff hand | Too much pretreat | Too much white ink |
| Random marks | Overspray | Contaminated platen |
| One garment only | Fibre content or finish | Untested blank |
| Time-of-day drift | Press recovery | Humidity |
Make it measurable
Every fix above depends on knowing what you did last time. Record applied pretreat weight, press time and temperature, and cure settings against the job, then a reorder can be reproduced rather than re-guessed.
Build a settings card per garment, not per shop
Most pretreat trouble is not a mystery, it is an undocumented variable. The shops that stop firefighting all do the same thing: they keep a short settings card per garment they run regularly, and they treat it as a standard rather than a suggestion.
| Field | Example | Why it matters |
|---|---|---|
| Garment and fabric | 100% ring-spun cotton, 180 gsm, black | Fibre content drives absorption |
| Pretreat weight | 24 g wet | The single biggest cause of dull white |
| Application | 2 passes, 40 psi | Uneven passes cause halos and patches |
| Dry method and time | Press, 60 s at 150C, no pressure | Under-dry causes wash-off |
| Underbase setting | Standard white, 1 pass | Coverage against ink cost |
| Cure | 160C for 90 s, verified by stretch test | Cure faults look like ink faults |
| Notes | Runs 10 s longer above 65% humidity | The variable you would otherwise forget |
One card per garment, kept with the job rather than in someone's head, converts a reorder from a re-test into a repeat. That is the whole point: a reorder that has to be re-derived is not a reorder, it is a new job with an old price.
Costing the failure rate honestly
Pretreat faults have a cost even when you catch them. A garment pulled at inspection is a blank written off, the pretreat and ink already spent, and the press time already gone. Two shops with identical prices and a two percentage point difference in reject rate have very different years.
The number worth watching weekly is rejects as a percentage of garments decorated, split by garment type. A single garment line accounting for most of your rejects is a sourcing decision, not a process one: some blends simply do not take pretreat well and no settings card rescues them. See choosing blanks for how to compare them before you commit.
Where the time goes
Pretreat is the least visible labour in a DTG shop. It happens before the interesting part, it involves waiting, and it rarely gets recorded. That is exactly why it under-recovers in pricing.
If the operator clocks on to the job at the pretreat station rather than at the printer, the hours land on the order and the job costing report shows what dark-garment work actually costs to produce, including the drying time nobody counts. Shops that measure this usually find dark garments take 1.6 to 2.2 times the labour of lights, which is a much bigger gap than most dark-garment surcharges assume. Fixing that is a pricing change, and how to price DTG has the arithmetic.
A weekly five-minute audit
Once a week, before the first job: weigh one pretreated garment to confirm the applicator is still delivering what the card says, wash-test a sample from the previous week, and check the platen and the dryer belt for pretreat residue. Three checks, five minutes, and they catch the drift that otherwise announces itself as a customer complaint a fortnight later. The same discipline applied across the shop is the QC checklist.
Printer's Friend tracks pretreat per line item and holds the cure schedule on DTG jobs, so the settings live with the order. Pricing the extra pretreat and white ink properly is covered in how to price DTG.