I’m Kayla, and I run small pop-up sales and help at a coffee cart on weekends. I’ve also done yard sales, church bake sales, and one very windy craft fair where my tent almost flew away. Cash is messy. People are nice, but things happen. So I keep a counterfeit currency marker clipped to my apron. (I unpack the whole saga in a step-by-step write-up right here.) It’s a tiny thing, but it saved me more than once.
Let me explain what I used and what happened, with real days and real bills.
What’s in my apron pocket
- Dri Mark Dual Test pen with the little UV light on the cap. This is my main one.
- MMF Industries detector pen from the office store. This was my backup.
- A cheap 10-pack from a big online store. These dried out fast, but I tried them first.
The Dri Mark stayed bright and didn’t leak. The MMF worked fine, just basic. The cheap ones smelled strong and quit on me by lunch. You get what you pay for, right? I actually ran a side-by-side test of half a dozen pens last fall—spoiler: some of them bled everywhere—and you can see the messy photo evidence in this field test recap.
How it works (in plain talk)
You swipe the pen across the bill. On good bills, the mark stays pale or fades. On fakes, it turns dark. The Dri Mark has a tiny UV light too. You shine it on the strip in the bill and the glow helps you spot weird stuff. Quick and simple.
Do I trust the pen? Yes. And no. I use it first. Then I still look for the watermark and the strip. Both is better than one.
The coffee cart morning: a damp twenty
I was covering my neighbor’s coffee cart during a rush. A guy handed me a wet $20. It had rain on it and a little smear from a receipt. I marked it. The line turned darker than I liked, and my stomach dropped.
I paused, smiled, and said, “One sec—this bill’s a little wet.” I waved the bill dry on the pastry case, tried again on a clean corner, and used the UV light. Strip looked right. Second mark stayed light. We were good. He thanked me for checking. I thanked him for the tip. We both exhaled.
Lesson: wet bills can fool the pen for a second. Don’t press too hard. Try a dry edge.
Church bake sale: the odd fifty
At a Sunday bake sale, a sweet grandma handed me a $50 for three banana breads. The pen mark stayed light. But the UV strip didn’t look right for a $50. I held the bill to the window and checked the watermark. It didn’t match the face. My chest got tight.
I kept it kind. “I think this bill might be off. Do you have another one?” She did. The second bill checked out. Later, she told me her bank replaced the first. We hugged. No drama. The pen helped me slow down and look.
Yard sale Saturday: the fake that I caught
This one still sticks with me. A teen brought a crisp $100 to buy my old camera. The pen mark stayed pale. So I almost took it. But the blue security ribbon looked flat, and the UV strip felt off. My gut said, “Wait.”
I called my cousin, who runs a taco truck and sees tons of cash. He said, “Use a second pen mark and tilt the bill again.” Second mark was still light, but the watermark face didn’t line up. I passed on the sale and asked for smaller bills. The teen left in a hurry. I think the pen kept me calm long enough to catch the rest. That close call echoed the painful day I learned to spot fake $20s the hard way, and I still cringe thinking about it.
Here’s the thing: good fakes can pass a pen. That’s why I pair tools—marker first, quick look second. If you want a full breakdown of the visual cues and back-up gadgets I lean on, check out this guide.
For an even deeper dive into spotting the subtle tells, I recommend skimming the comparison photos over at PrettyFakes, because those side-by-side images train your eye fast.
If you need an official cheat-sheet straight from the source, the Bureau of Engraving and Printing offers a handy Quick Glance Reference Card you can keep in your cash box (you can download it here).
Craft fair marathon: pen stamina test
July heat, metal table, no shade. I did about 300 marks that day. The Dri Mark kept going. The MMF was fine for backup. The cheap pens? Two dried out by noon. One leaked in my tote and stained my square reader pouch. Not fun.
The Dri Mark tip stayed firm. The cap didn’t loosen. Small stuff, but when your hands are sticky from lemonade, it matters.
What I like
- It’s fast. One swipe and you can move on.
- It’s cheap peace of mind. Five to ten bucks, tops.
- The clip holds on my apron. Silly detail, but huge when you’re busy.
- The UV light on the Dri Mark is handy at dusk or under a tent.
What bugged me
- False alarms on glossy or wet bills. It happens.
- Tips can fray if you press too hard.
- If you leave the cap off, it dries out. That’s on me. Still annoying.
- It’s not a final judge. Skilled fakes can pass the pen. So you need your eyes too.
A tiny test I did at home
I marked a scrap of printer paper. It turned dark right away. I marked a $10 from my wallet. Pale line. That gave me confidence. Simple checks like that help you trust your gear.
Tips that saved me (learned the sweaty way)
- Mark a blank, light area, not over heavy ink.
- If the bill is damp, wait a beat, then try a second spot.
- Hold the bill to light for the watermark and security strip. Takes two seconds.
- Keep a spare pen capped tight in your cash box.
- For busy crews, set a simple script: “Quick check, thanks!” It keeps the line calm.
- If a bill feels wrong, ask for another. You’re not accusing. You’re protecting both of you.
For an academic-style checklist that walks through each security feature in detail, Cornell University’s Treasury Division has a concise printable guide you can grab here.
Who should keep one handy
- Food trucks, pop-up shops, and farmer’s markets.
- Yard sales and estate sales.
- Church and school fundraisers.
- Cash-only nights when the card reader acts up.
- Anyone who handles bigger bills once in a while.
My picks after months of use
- Dri Mark Dual Test: my go-to. The UV light makes it a two-in-one.
- MMF Industries pen: solid, simple backup.
- The bargain multi-pack I tried: false savings. Dried out, messy caps.
Price and value
I spend about the cost of a couple lattes and get months of use. One pen lasts a few hundred marks for me. The UV model needs small button batteries, but they last a long time. I replace my main pen each season, just to be safe.
Bottom line
I carry a counterfeit currency marker because it keeps me calm. It speeds up the easy calls and buys me time for the tricky ones. It’s not magic. But paired with a quick look at the bill, it works.
By the way, once the cash box is locked and the tents are folded, I know plenty of vendors—including me—who like to unwind with a little playful phone time. If your idea of stress relief involves spicy text rather than counting quarters, you might check out this no-judgment sexting space for private, flirty conversations that let you set the pace and the heat level from your couch.
For sellers who do pop-ups in Fairfield and want an extra channel to reach interested adults—sort of like placing a classified ad for your next event—you can browse the local listings on Backpage Fairfield where everything is organized by category, making it easy to connect with nearby customers without blowing your budget on big-platform advertising fees.
Would I buy again? Yes. I already did. One in my apron, one in my cash box, and—because I’ve learned—one more in my glove compartment. You know what? That little pen has saved me dough, and at a bake sale, that’s saying something.