Tapioca and potato modified starch are both used as the base of dry wallpaper adhesive powder, and buyers often ask which one is better. The honest answer is that KARN publishes model data, not a starch-versus-starch ranking. What you can verify is the model you order, the viscosity published for that model under a fixed test method, and the result of a trial on your own wallpaper and wall.
This article is written by the KARN team and uses company-published product information. It is first-party buyer education, not an independent laboratory comparison, and it does not claim that one starch suits every wallpaper.
What each starch is doing in the powder
Both materials are plant starches that have been modified so the powder disperses in cold water and builds a workable paste. That common ground is why both are sold as "dry wallpaper glue powder" at all.
The differences that reach the buyer appear in the finished model: which starch the grade is built on, what viscosity that grade carries under a fixed method, and how the paste behaves on a wall. In the current KARN range, K6 is the ordinary grade on tapioca modified starch. 999 and 999+ are built on potato modified starch: 999 is the main export model and 999+ is the anti-mold grade on the same potato base.
The models KARN actually publishes
The finished grades are measured the same way: a 5% solution on an NDJ-8 viscometer with a No. 4 rotor at 6 rpm, quoted with a ±10% tolerance. Read the table as a description of the powder under those conditions, not as a prediction of what happens on a vinyl-faced roll or a bare plaster wall.
| Model | Grade | Base starch | Published viscosity |
|---|---|---|---|
| K6 | Ordinary grade | Tapioca modified starch | 38,000 ±10% mPa·s |
| 999 | Main export model | Potato modified starch | Per model TDS |
| 999+ | Anti-mold grade | Potato modified starch | Per model TDS |
| KN-999 | Raw-material base powder | Modified starch base | Different instrument; not comparable |
The KN-999 row is in the table because buyers see the model next to the others on the product list, not because it belongs in the same comparison. Its figure was measured on a different instrument with a different sample preparation. Different instrument means different number, and a different number does not mean better or worse.
Why the starch name alone does not settle the choice
Two suppliers can both say "potato starch" and ship pastes that behave differently, because the modification, the solids level and the granulation all sit between the raw material and the finished bag. The reverse is also true: a tapioca-based grade and a potato-based grade from the same factory can end up closer to each other in working behaviour than two potato-based grades from different factories.
For a buyer, the starch name is a sourcing fact, not a performance specification. The performance specification is the model, the published viscosity with its test conditions, the packaging, and the trial record you keep.
KN-999 is not a fourth grade of the same comparison
KN-999 is the raw-material base powder offered for repacking. It is easy to read the number next to it as "lower than 999, therefore thinner", and that reading is wrong twice over: it is a different product position, and it was measured on a different instrument.
If you are comparing KN-999 with a finished grade, compare it on the property you actually care about — how it behaves in your repacking line and in the customer's bucket — not on a raw viscosity digit.
How to test the difference yourself
- Pick two models, not four, and mix both at the same powder-to-water ratio. The published guidance is 1:25 or 1:30.
- Weigh powder and water, and record water temperature, mixing time and rest time before use.
- Spread both pastes on the same wall with the same tool, then hang the same wallpaper you actually sell.
- Record open time, how far the strip slides, seam tightness, and the dry result after a full drying period.
- Keep a roll offcut and the mix record with the samples, so a bulk order can repeat the mix that passed.
A cup test is not enough. The differences buyers report between starch bases usually show up in open time and seam behaviour on a full drop, not in how a spoonful looks.
What to put in the inquiry
State the market, the wallpaper type and weight, the wall condition and primer, the pack format you plan to buy, and the models you want to compare. With those details the model shortlist, the TDS for each model and the sample arrangement can be discussed without guessing. Bulk supply is a 20kg kraft paper bag with a PE liner; OEM small packs run from 200g to 1kg.
Price, MOQ, lead time and freight are quoted against the inquiry, because they depend on the model, the pack format and the route.
Frequently asked questions
Is potato starch better than tapioca starch for wallpaper adhesive?
Not as a general rule. Both are used as the base of dry wallpaper adhesive powder, and the published difference is per model: K6 on tapioca carries a nominal 38,000 ±10% mPa·s under the 5% / NDJ-8 / No. 4 rotor / 6 rpm method. Which model suits a given wallpaper is settled by a trial, not by the starch name.
Can I compare the viscosity numbers directly?
Only inside the same method. The finished grades share one method and can be compared with each other. KN-999 is measured differently and is not on that scale, so its number should not be ranked against K6, 999 or 999+.
Does a higher viscosity number mean a stronger bond?
No. The figure describes paste thickness under fixed laboratory conditions. Bond performance on a wall depends on the wallpaper, the substrate, the primer, the ratio and the application, which is why the trial record matters more than the number.
Can KARN supply both starch types in one order?
K6, 999 and 999+ are separate models with their own packaging and documentation, so a mixed order is a commercial question rather than a catalogue default. State the models and quantities and the packing arrangement is confirmed in the quotation.
Model data, packaging and test conditions on this page come from KARN's published product information. Review the product pages and technical documents, or send the application details through the contact page.