In all of these tests, I used relatively fresh Expo brand dry-erase markers and Premium stock DriveThruCards. Obviously I don't live in a lab, so I couldn't control other environmental factors like humidity and temperature, but I hope these results hold true for most home use.
Naturally, I tweeted the results as they arrived.
Test 1: Black Ink Over Time
The first test I set out several cards covered in dry-erase Black ink. After the allotted about of time, I wiped away as much ink as I could with a dry paper towel. The results were very good for my purposes. After a typical game length, there would be minimal staining on the card. Even after 24 hours, the haze was pretty tolerable. I'm not sure how well it would hold up over repeated use, but for occasional use I think it's pretty good!Experimenting with DriveThruCards Premium Stock and dry-erase markers. Erased with paper towel at 10', 20', 30'. Negligible stain so far. pic.twitter.com/2G0nc2GfDg— Daniel Solis (@DanielSolis) May 12, 2017
Test 2: Colored Ink Over Time
Nat Levan was curious about how the different colors of ink might fare after a 24 hour period, so I set out all the colors I had available. Again, I wiped away as much ink as I could with a dry paper towel. The results were still pretty tolerable, but as he had expected some colors seemed to stain more than others depending on the light. Blue and Red seemed most hazy after the testing period.24hr Results: Dry-erase on DriveThruCards premium stock. Pic 1: one wipe. Pic 2: full scrub. All haze, but blue stains most. @OakleafGames pic.twitter.com/uRN1EeLldT— Daniel Solis (@DanielSolis) May 14, 2017
Test 3: Colored Ink on Printed Surfaces
After those last two tests, I had a hypothesis. I wondered if it would do even better if it had an ink layer printed on it already to fill in all the pores of the paper.Dry-erase experiment 3 had some surprising results. Conclusion: Don't use dry-erase on printed surfaces. It's more absorbent than blanks. pic.twitter.com/Q7sQFVRwAP— Daniel Solis (@DanielSolis) May 15, 2017
Photo 1 shows four different colors of Expo dry-erase markers on the printed cards after 24 hours of drying.
Photo 2 shows two different methods of erasure after the drying period was complete.
(2a) The lower half of each sample shows how much I was able to remove with aggressive scrubbing with a dry paper towel. That stuff is really well caked on. I thought this hypothesis was a bust, but I remembered someone on my timeline mentioned a trick for removing stubborn dry-erase stains. Just write over the stain again with a marker and erase both at once.
(2b) The upper half of each sample shows how that worked out. Much better than a paper towel alone, but still more significant staining than on the less-printed cards.
Photo 3 shows a close-up of the red sample results from Experiment 2 and the red sample results from this experiment. Even after using the marker trick, the surface from Experiment 2 was easier to erase and had less staining.
Conclusion: That hypothesis is busted. I suspect that the unprinted surface of the stock is less absorbent at room temperature. The ink layer on top of the paper is somehow more porous, therefore takes the dry-erase ink more readily. So, if I'm to use cards as dry-erase components, I must keep the writing surface as blank as possible.