By day, his signs guide nature lovers through City of Boulder Open Space with precision and clarity. By night, his signs guide music lovers, teasing them with bloated cartoon superheroes, grinning goats' heads and buzzsaw horny toads.

By trade, Jeff Holland is a cartographer,heading a team of map makers in the city's Open Space Department. By passion, the 39 year-old operates Cryptographics, designing posters mostly for underground music concerts at venues around the country.

In an age where true album art disappeared along with vinyl records, artists such as Holland recreate the visual aspect that used to accompany rock music.

Such art signals a resurgence in the trend begun by poster artists such as Stanley Mouse, Alton Kelley and Rick Griffin, for the Grateful Dead and other psychedelic bands in the '60s. It's a trend recently jump-started by artists including Frank Kozik in Austin and San Francisco and an artist named Coop in Seattle.

Since 1993, Holland has designed more than 160 eye-grabbing posters to advertise concerts in the Boulder-Denver area, primarily at the Fox Theatre, as well as shows in Oregon and Texas. Many of his posters are on display inside Caffe Mars, 1425 Pearl St., until Aug. 29.

The posters borrow some of the computer graphic design talents Holland learned while working with the city, and combine them with the taste for out-of the mainstream music he's had for most of his life. "The maps are creative but they're very restrictive in terms of what you can do. The layout and design and all the work that goes into cartography is underappreciated," Holland said. "The posters are an outlet for imagination and expression. They supply a creative balance that allows me to stay sane. "Plus, I get into free shows and get to drink beer."

While a few copies of Holland's signs and maps can be found along open space around the county, his posters are pasted up by the hundreds on kiosks, telephone poles and record stores. "If you want to get art up, this is the way to do it," he said. "The fun is simply in having it up."

Open Screen Inside a barn he rents from a former professor in Southeast Boulder (where he also keeps two horses), Holland recently poured globs of fluorescent ink on a hand-operated silkscreen and smoothed it over a sheet of heavy paper. Holland hand-silkscreens between 50 and 150 posters per batch. He first designs a separate printing run for about 300 less- expensive single- color copies done by machine.

On this particular day, the poster in Holland's workshop advertised a show scheduled Friday, July 19. It features a North Carolina band called Southern Culture on the Skids, a kitschy hillbilly send-up group whose most recent album is called Dirt Track Date. Holland eyed the poster, which depicts a woman in a bikini toweling off near a hot rod. "To me, this is what the music is about," he said.

Holland often hides subtle innuendo in his posters, gleaning ideas from a variety of areas. He has a collection of pictures of petroglyphs - ancient rock drawings - which end up in some of his posters. He's also begun collecting Japanese comic books. On a recent trip to EcoCycle, Holland found a goldmine: a pile of Cold War newspapers from Russia, full of propaganda pictures.

Some of the hidden messages in his posters depict the changes he's seen in Boulder since he moved here in 1976.

Some of his hidden messages are easier to decipher than others.

A poster for Seattle music hero Tad depicts handsome but creepy Siamese twins in a checkered shirt - a jab at conformist fraternity culture. Another not-so subtle poster for the band Fear asks, "When the revolution comes, will they take away my trust fund?"

"The images and ideas that I'm working with have a lot of meaning to somebody who can crack the code, Holland said. "But the symbols that translate with a lot of meaning can be a lot different, depending on people's backgrounds. I'm not necessarily interested in having one precise response."

Sometimes the responses are met with a raised eyebrow. Such as the poster for surf-guitar legend Dick Dale, in which Holland created a surfer, and on a whim added a pair of horns and a trident. "Some of the people I work with think I'm a little wild sometimes - especially when I draw some of the girls or the devil stuff," he said.

Despite the rare criticism, Holland stands by everything he prints. "I don't think words and images can hurt anybody," he said. "Reduced to the lowest level, it's that you are able to com- municate, not what you are communicating. Everyone gets to fill in their own blanks."

Free time By selling his posters for $10 to $15 each, Holland says he barely pays for the printing time and cost of ink, considering it takes 35 to 40 hours to print 100 five-color posters. But when the bands are hardly raking in the cash, Holland says it simply isn't fair to charge much.

Some poster shops recently hiked the cost of artwork for the Grateful Dead and Nirvana after the deaths of Jerry Garcia and Kurt Cobain. Holland frowned at the practice, saying "the business end of it is not what it's about.

"Most of all, the posters are about music," he said. Holland mails copies of the posters around the world to people who order them from his site on the World Wide Web. He's made contacts with many of the bands he promotes, and one day hopes his art might make it onto an album cover.

"One of the things that's weird here is that no one else is really doing this, and I haven't figured out why," he said. "I'd like to see it. Competition to me is an incentive to work harder. I'd love to see some other people start doing this kind of stuff." Until then, Holland said he'll continue to spend his spare time in front of the computer screen and the silkscreen. When informed that many of the posters look like they were designed in the basement by some punk rock kid, Holland laughed. "In a way, that's exactly what I am," he said. "I've never been able to grow up, and I don't anticipate it. But I'm having fun, and I don't think everyone can say that."

Surf and twang music pours from Jeff Holland's studio in southeast Boulder, where he often spends weekends creating poster art.