A trip into the vault at Warner Bros.

We pay lip service to old Hollywood, to the storied age of the movie studios, but do we really know what happened on those fabled lots? Do we understand that world that is no more? A fascinating new series put together by the UCLA Film & Television Archive offers a window into that reality and a whole lot more.

“Rarities From the Warner Archive Collection,” a 19-film program starting Friday at the Billy Wilder Theater at the Hammer Museum in Westwood, is of great interest on a number of levels. It runs the gamut from a 1927 silent that stars John Barrymore (“When a Man Loves”) to 1958’s “Too Much Too Soon,” which explores the actor’s real-life relationship with his daughter Diana and stars a poignant Errol Flynn as the “Great Profile” himself.

The series came about as an offshoot of Warner’s welcome decision to begin releasing — as on-demand DVDs — the literally thousands of titles in the studio vaults that have never been available in this format. The studio donated copies of these DVDs to UCLA’s research collection, and this series features 35mm prints of the best and most interesting of the more than 600 titles donated so far.

All kinds of films are represented in the series, pictures that are compelling in and of themselves and as representative of larger trends. These include unaccountably overlooked classics such as the James Cagney-starring “The Strawberry Blonde” and transgressive, kept-under-wraps hot potatoes such as the Al Jolson-starring “Wonder Bar.”

There are films understandably forgotten as well as unusual, one-of-a-kind productions such as the ripped-from-the-headlines “I Was a Communist for the FBI” and the gritty, socially conscious “Juke Girl,” starring Ann Sheridan and a certain former president and advertised as follows: “She was lovely to look at and dangerous to love. Until she meets Ronald Reagan, who knows what she wants.” ’Nuff said.

Taken as a whole, what is interesting about these films is that their impressive range of subject matter and genre mark them as artifacts from a time when studios such as Warner’s made pictures for a wide variety of tastes and audiences. Though they are quirky and diverse, each has some element that a broad general audience would find worth their time. Those were the days, after all, when adults didn’t need the equivalent of a nuclear device to blast them out of their living rooms and into a theater.

These films illustrate, in the best sense, what historians and critics mean when they talk about Hollywood as a factory system, a place where teams of superb in-house professionals polished everything that appeared on the screen.

The fine 1943 drama “The Hard Way,” for instance, may have had a big name in star Ida Lupino and expert direction from Vincent Sherman, but it also benefited from superb writers in Daniel Fuchs and Peter Viertel, a legendary cinematographer in James Wong Howe, and even future directing great Don Siegel in charge of the film’s montages.

Every director was not an auteur in this system, and few if any celebratory tracts have been written about individuals such as Edward A. Blatt, H.C. Potter, David Butler or Art Napoleon. But they got the job done.

Actors had to make do both with the assigned directors and with whatever roles studio executives wanted to see them in, no matter how unrewarding the picture, which resulted in a young and vibrant Kirk Douglas lighting things up in the little-seen “Top Secret Affair” and George Raft donning a trench coat and dealing with random Nazis roaming through Turkey in Raoul Walsh’s “Background to Danger.”

The factory system also provided a mechanism through which future stars could be introduced in supporting roles and then groomed for bigger things. Bette Davis, for instance, is so incandescent in a minor role as a society spitfire who flirts with crime in “Fog Over Frisco,” reportedly one of her favorite parts, that you could mistake her for the star.

The studio system also meant that major stars such as Cagney could take on offbeat roles without endangering their careers, or their paychecks, which is just what happened in the eternally charming “Strawberry Blonde.”

Co-written by Julius and Philip Epstein (who also had a major hand in “Casablanca”), “The Strawberry Blonde” fits into no genre or recognizable category. Costarring Olivia de Havilland and Rita Hayworth and set in the Gay ‘90s (with the music to prove it), this story of how Cagney’s irascible hero, given to saying things like “I take nothing from nobody, that’s the kind of hairpin I am,” comes to understand the difference between love and infatuation is a film to savor over and over again.

A very different but equally remarkable production is 1934’s “Wonder Bar,” which costars Jolson with Dick Powell and the super glam Dolores del Rio. With its risqué humor marking it unmistakably as a pre-Code item, “Wonder Bar” has enough disorienting material, from extensive blackface musical numbers that are painful to watch to Busby Berkeley’s still-delirious dance routines, to remain defiantly one of a kind.

While it’s great to have beloved films such as “The Strawberry Blonde” in the series, it is equally satisfying to discover unaccountably neglected gems. “The Unsuspected” is a crackling film noir, “It’s Love I’m After” features terrific battle-of-the-sexes banter between Leslie Howard and Davis as actors whose private lives play out on the stage, and 1938’s “Four Daughters” is not only a dramatic romance with a rich appreciation of character but it also showcases John Garfield in an Oscar-nominated anti-hero role that predates Brando and Dean by decades.

Friday night’s opening program is a rarity in and of itself. It features Barrymore’s “When a Man Loves,” based on “Manon Lescaut” and presented with a Vitaphone orchestral soundtrack recorded by a moonlighting New York Philharmonic, but that’s not all. Also on the bill are a trio of rare Vitaphone sound-on-disc shorts that re-create the program that accompanied the film when it premiered in Manhattan in 1927.

Perhaps the most unusual film in the UCLA series is the eerie “Between Two Worlds,” a World War II-era updating of a 1924 play about a boat taking anxious and uncertain people on a journey to the afterlife. Yes, the afterlife. Alternately awkward and genuinely affecting, this is an imperfect film, but flawed as it is, it’s hard to imagine a studio trying anything like it today, and that is a shame.

kenneth.turan@latimes.com