Old, colorful bottles line a window of Fred Bjork’s Colorado Springs home.

“The morning sun hits this wall and puts on a rainbow effect,” he says. “That’s one reason people collect bottles.”

The reasons for his collection are varied — as varied as the bottles themselves, ranging in shape, color and age.

Where to begin amid the 6,000 or so?

“I dug all those whiskey bottles out of the ground,” Bjork says, pointing to a bucketful recalling Colorado’s Wild West.

Other bottles came from grounds far beyond this state.

“I just obtained this one,” he says, showing a seltzer bottle from Paris.

He steps around bottles in all shades of red, orange, yellow, green, blue, purple and more. “Look at the color on this one,” he says, admiring a teal bottle that once kept malt.

These bottles kept ink, those kept medicine. “Here’s an English mineral water bottle,” Bjork says, admiring the label a hand placed in the 1880s.

“This is my earliest bottle,” he says, grabbing one that contained champagne in the late 1700s.

This is his rarest, he says: “It’s the only one known in the world. It’s a German poison bottle.”

Which leads him to all of his other historic poison bottles — about 1,400 of them. Poison is the proudest part of his collection. And also the weirdest, he knows.

He shrugs and grins. “I’m not a traditional kind of guy. I don’t think like everybody else.”

Which might describe his fellow enthusiasts, his fellow members of the Antique Bottle Collectors of Colorado.

Bjork is vice president of the club with about 50 active members — a number that speaks to what Glen Preble knows to be an increasingly niche hobby. Preble has been a member of the Antique Bottle Collectors of Colorado since the 1970s, going back to the club’s early years.

“It’s been hard recruiting young people in the hobby,” he says. “I guess they’re more interested in video games and modern-day things. They just don’t seem to have the same appreciation for history.”

That appreciation explains Preble’s collection, which he suspects ranges somewhere between 3,000 and 3,500 bottles. He started with beer bottles. Then he got interested in Hutchinson soda bottles, as many collectors do, for the peculiar shape, array of color and patented stopper that made a “pop” sound heard around the nation in the late 1800s.

Then Preble got interested in old whiskey bottles. “Then a good friend of mine, he was kind of an oddball, and he started collecting milk bottles, and all of a sudden I became a milk bottle collector,” Preble says.

Of top interest today: three more particular bottles that would complete his collection of bottles representing every Colorado town that had a drug store in the state’s early days. This was the subject of Preble’s book, “The Rise and Demise of Colorado Drug Stores: 1859-1915,” in which he aimed to catalog every bottle from every pharmacy of the era.

“About 756 pages, I decided to call it,” he says.

More than digging for bottles, Prebble has dug for information. “It’s not enough to just have a bottle,” he says. “There’s a story behind the bottle.”

There’s a story behind every bottle of Matt Poage’s smaller collection, mostly focused on Denver’s Western Glass Manufacturing Co. of the early 1900s.

“It’s a tangible piece of the past that you’re holding,” Poage says.

Poage is president of the Antique Bottle Collectors of Colorado. It was one such club to sprout across the country after one man’s bottle-digging venture in 1959 around the Sierra Nevadas.

The man, John Tibbitts of Sacramento, Calif., recalled the venture in a publication of the Federation of Historical Bottle Collectors, today’s national organization that grew out of his home. Tibbitts’ account begins with a Washoe Zephyr — “a very strong, cold wind that blows down the eastern slopes of the Sierra Nevadas,” he wrote.

This was what he and his wife encountered that day in 1959. “It was miserable, but we had struck a spot with a lot of old miniatures, Jamaica gingers, Hostetter’s Bitters, etc.,” Tibbitts wrote. “Any bottle digger knows what we did; we braced ourselves against the zephyr and kept on scratching.”

Another couple was scratching nearby, the Tibbittses discovered: “We and they were extremely happy to find we were not the only crazy bottle diggers in the world.”

Many more would connect through the Federation of Historical Bottle Collectors, which maintains a virtual museum. From the computer, one can explore galleries of historic bottles for perfume and cologne; for beer and soda; for medicine and poison; for foods and sauces.

Another museum, the National Bottle Museum in Ballston Spa, N.Y., displays local mineral water bottles from the early 1800s. This was a time when “all bottles were manufactured exclusively with hand tools and lung power,” reads an account on the museum’s website.

More industries would boom across the East Coast and across the heartland to the opposite, emerging coast: “The West was being settled, creating a demand for millions of whiskey flasks and spirits bottles to help men cope with loneliness and hardship. Every pharmacy, every producer of patent medicines, every brewery, dairy farm and manufacturer, required hand-made glass bottles.”

They would be sought generations later by the adventurous, curious likes of Bjork.

“I’ve dug from Europe to California and anywhere in between,” the Colorado Springs collector says. “I used to dig up in Cripple Creek before the casinos came in. … I’ve been buried four times, by the way.”

He’d dig deep where old maps showed old dumps — sites where bottles might have been left, unbeknownst to homeowners. Bjork would knock on doors and ask for permission with a shovel in hand.

The appeal remains. “It’s like digging for buried treasure,” Preble says. “It’s finding that old or unique bottle that may have previously been unknown.”

But things are different these days, Bjork says. “In the olden days you could go to the edge of town to somebody’s backyard and they wouldn’t care. But now with all the liability concerns, they don’t want that.”

And so collectors often turn to shows; sellers from near and far filled about 60 tables of the Antique Bottle Collectors of Colorado’s annual gathering in September. Collectors scour antique shops, yard sales, estate sales and an online network of sellers.

Bjork knows the network well, having long sold on eBay under the name “lovetheglass.” That’s what it’s about for him, he maintains: the simple love of the glass, not the money. Though, the money helps him buy the next bottle he seeks.

He knows the rarest of bottles to be worth tens of thousands of dollars. He sounds equally excited and troubled by this.

“Money has hurt the hobby,” Bjork says. “Just like real estate, when there’s too much money involved, the desire is not to have someone live in the house, but to flip the house and make money.”

Jealousy and greed might be derived from the Federation of Historical Bottle Collectors’ code of ethics. “Respect” is listed at the top. “Personal or negative feelings about an individual within the organization are not acceptable,” the list continues, followed by guidelines for digging on public and private lands. Other guidelines regard “fair, honest and considerate business ethics.”

Perhaps the hunt leads some astray. The hunt for all those bottles and all that information about Colorado’s pharmacies started fun for Preble. “I’d like to say it was a lot of fun, but it was more work than fun,” he says.

A subtitle accompanied that hyper detailed book he wrote: “A Prescription for the Bottle Collecting Habit.” It’s a habit or maybe a “bug,” Preble says.

“It’s not enough to have an example of something; you have to have as many examples of that something as you can find,” he says. “So maybe in that way it is kind of a sickness. Maybe you have a little OCD thing going on.”

Maybe it’s good to be limited by storage space, says the president of the Antique Bottle Collectors of Colorado.

“I don’t want to get overwhelmed with it,” Poage says. “I know some things come between, not necessarily relationships, but everyday life sorts of things, and I don’t want that. So I do draw the line. Because at the end of the day, it’s just stuff.”

Just stuff, Bjork agrees. But valuable stuff — in ways that have nothing to do with money.

“It’s about the history,” Bjork says. “It’s about trying to restore that history, trying to restore that time and place. That’s why I have those tumblers over there to clean them.”

And maybe he’ll place them along a window, just to see the sunlight come through the colors.