Rub Testing Procedures Explained | Rub Tester | Danilee Co.

Specimen Preparation

For a complete rub test, you'll need two pieces: the test specimen and its corresponding receptor. Cut the test specimen to about six by three inches. Ideally, the six-inch dimension should be cut across the grain when possible, avoiding any pressed or cut scores.

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For the receptor strips, use the same stock as the test specimen. Cut 2x7-inch strips for the four-pound weight, placing the strip face up against the scoring device pin and scoring at the white dot positions to facilitate proper bending during testing.

For two-pound weights, prepare 2x5 1/4-inch strips the same way but score at the red dot positions. Detailed tutorials are available online (click here for a picture tutorial or click here for a video tutorial).

Dry Rub Testing

Attach a 2x7-inch test strip to the four-pound test block, ensuring the abrasive surface faces away from the rubber pad. Securely mount the test specimen (printed side up, if applicable) on the rubber pad of the base plate with a hold-down bracket.

Thoroughly brush both the test strip and the test specimen using a camel-hair brush (not included) to remove any dust or foreign materials.

Place the weights over the sample, making sure the 2x4-inch rubber pad of the test block covers the test area. Ensure both surfaces are dirt-free. Preset the tester for ten strokes or adjust to the standard stroke count desired.

Power Connectivity

Plug the power cord into the correct voltage outlet, and the display will show a version number such as 1-0. If the machine is already plugged in, touching any key will reactivate the display with the previous settings. For speed 1, low count rub tests, cycle the machine once to reset the stroke count. Note that the display will automatically turn off after about 60 minutes of inactivity.

Count Configuration

Each press of the COUNT button increases the cycle count by one. Holding down the COUNT button will accelerate the count increment. At 10, the count increments by tens; at 100, it increments by hundreds. Release the button to reset the count. While the motor runs, the COUNT button is disabled. The maximum count is 999. Press Reset to clear the count. If the motor is running, Reset stops the motor and resets the count to 000.

Note: Adjusting the cycle count displays the starting point, not the previously set count. For example, if the cycle count is 100 and the motor stops at 95, pressing the COUNT button sets the count to 96.

Start & Stop Function

The START/STOP button controls the motor. When the count reaches zero, the motor stops, and the display resets to its previous setting. Pressing START/STOP while the motor runs halts the motor without clearing the display. Press START/STOP again to resume the count from where it stopped.

Note: The motor will not start if the display reads zero.

Motor Speed Adjustment

Press the SPEED button to cycle through speeds 1 to 4, indicated by the respective LED lights:

• Speed 1 (21 cycles per minute)
• Speed 2 (42 cycles per minute)
• Speed 3 (85 cycles per minute)
• Speed 4 (106 cycles per minute)

The machine defaults to Speed 1 upon first being plugged in unless the SPEED button is pressed. The motor speed can be adjusted anytime, whether before or during operation. The speed setting persists when the Reset button is pressed; press SPEED again to change it.

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Reset Button

Pressing this button resets the board count to zero. If the motor is running, it turns off. This can be done at any time for convenience.

Once the rub test is completed, examine both test strips for signs of transfer. Staple the pieces together for visual reference, indicating the number of rubs performed. Always store the test block on its side after use.

Wet Rub Testing

Utilize the same mounting method as the dry rub for wet rub tests, employing the two-pound test block. Preset the tester for one rub. Apply three to six drops of water on the printed surface and ensure the test block covers them. Start the test immediately by pressing the start button. Examine both surfaces for color transfer after one stroke, repeating as necessary until ink failure or surface abrasion is evident.

Wet Bleed or Transfer

Mount a 2x5 1/4-inch strip on the two-pound test block with the smooth side out, saturate the blotter with water, and place it on the sample. Keep it in position for four minutes without rubbing, then examine for ink transfer to the blotter.

Wet Smear

Perform the test with a water-saturated blotter on the two-pound block. Actuate for one stroke and examine for color transfer. More rubs may be necessary for samples requiring high water resistance. An alternative method uses a 2x6-inch piece of 80X80 count bleached muslin over a blotter, which minimizes surface abrasion effects on the blotting paper.

Functional Rub Uses

Functional Rub encompasses various specific uses for the SUTHERLAND Rub Tester. Inks that pass standard tests might fail under exposure to foreign substances like Cod liver oil or toothpaste. Reporting functional rub tests requires specifying the rub count, contact time, and testing conditions.

Evaluating Test Results

Adopt a practical approach when evaluating tests. Few inks will pass both wet and dry rubs without minor color transfer. Determining ink suitability involves comparative tests under identical conditions.

Quantitative evaluation methods measure test strips with a densitometer or spectrophotometer before and after testing, recording changes in density or delta E (CIE L*a*b). Larger numbers signify greater rub damage. Account for the time between printing and testing, especially with slow-drying inks. Protect printed samples from dust and dirt during intervals.

Ensure test samples represent the run, avoiding sheets with excessive anti-offset materials or dust accumulation.

New Rubber Pads

Click here for information on replacement pads.

Optional Heated Weight

Click here for information on the heated weight.