How to evaluate a silica in a toothpaste structure trial

In short: Make the paste with the candidate silica in place of the incumbent at the same level, in your own formulation, and follow three things over four weeks: viscosity, stand-up of the ribbon, and separation in the tube. Judge cleaning on a standard brush-abrasion rig rather than by feel. Sensilchem starts oral-care trials with CENSIL 310, with CENSIL 320 and the fine powder CENSIL 150 beside it.

What you need

  • Your production toothpaste formulation and the incumbent silica
  • Candidate sample set from the porous and fine-powder families
  • Vacuum planetary mixer, laminate tubes or jars, viscometer, a glass slide
  • Warm cabinet for accelerated storage and, if available, a brush-abrasion rig

Step by step

  1. Make the paste the same way every time

    Order of addition, vacuum, mixing time and temperature all affect structure. Write the procedure down and use it for every candidate; a paste that differs in process cannot be compared on silica.

  2. Measure viscosity after the paste has rested

    Read viscosity the next day, not straight from the mixer, and again after one and four weeks. Silica-built structure changes for the first day or two and the settled reading is the meaningful one.

  3. Extrude a ribbon onto a slide

    Squeeze a ribbon from the tube onto a glass slide and photograph it edge-on. A ribbon that holds its shape has enough structure; one that slumps or strings has too little or the wrong kind.

  4. Watch for separation in the tube

    Store filled tubes warm and cut one open each week. Clear liquid at the nozzle end or a dry rim at the seal end is syneresis, and it shows up in accelerated storage before it shows up in the market.

  5. Run cleaning on a rig, not on a thumb

    If the trial includes cleaning, use a standardised brushing rig with stained substrates so that the comparison is repeatable. Feel on the finger tells you about grit, not about cleaning.

  6. Compare the fine powder for appearance

    For a translucent or gel paste, make one batch with the fine powder grade and hold it against the others in a clear tube. Appearance is decided by the customer's eye, so give them something to look at.

Mistakes that spoil the comparison

  • Reading viscosity straight after mixing and calling it the result.
  • Comparing candidates made on different days with different vacuum levels.
  • Skipping the four-week tube storage because the first-week ribbon looked fine.

Questions we get asked

How much silica goes into the trial paste?

The same level as the incumbent, so that the silica is the only variable. Optimising the level comes after the grade has been chosen, not during the comparison.

Can Sensilchem provide oral-care documentation?

The documentation set and the destination-market position are confirmed per enquiry. Tell us the country and we will state what can be supplied before samples ship.

Tell us what is failing in the process

The material you use now, the formulation or resin, the equipment and the target you need to hit. That is enough for us to say whether we have something worth testing.

Request a sample Contact us
Application & sales Ms. Nina Zhang nina@sensilchem.com +86 597-2200392
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