The tapes of Whitesnake's 1984 album 'Slide It In' and 1989's 'Slip of the Tongue,' needed for the British hard rock band's commemorative deluxe CD and DVD sets, were found in a former limestone mine called Iron Mountain Storage Facility in Pennsylvania.

"You can imagine this, hundreds of feet below the ground, tons of shelves with analog tapes stacked," muses lead singer David Coverdale, who hadn't heard of the high-security storage facility that has been in business since 1951.

"Of course, in [the '80s] you'd have alternate takes or radio mixes and we've just slammed these packages full of goodies."

Whitesnake has reportedly sold more than 100 million albums in its 32-year career. While 1987's self-titled album was its biggest seller, going eight times platinum (8 million units sold), it was flanked by two albums that have now been digitally remastered and released as special deluxe editions with bonus material.

'Slide It In – 25th Anniversary Deluxe Edition' and 'Slip Of The Tongue – 20th Anniversary Deluxe Edition, ' include rare and previously unreleased audio and video, new cover art and a 24-page booklet including rare photos and new liner notes.

"I've got so much material which I never thought would ever be interesting to anybody else, but once I started Whitesnake.com and got the interactive experience going, I found out that people want to hear cassette demos of original songs. So we tried to get as good quality as possible out of these things," says Coverdale. "Of course, there is actually an audience for that so it becomes very interesting to the hardcore fan to hear the period of the song – the first ideas of the demo to second stage, the musicians being introduced to it, rather than the finished product. It's an interesting journey."

In the U.S., 'Slide It In' was certified double platinum. The album was slicker and more radio-friendly than the U.K. version, so the new deluxe edition includes eight U.K. tracks, and other bits and pieces.

"There's stuff that's been done in more recent years," Coverdale says. "For instance, there's an unplugged version of 'Love Ain't No Stranger,' featuring my very dear friend and former colleague Adrian Vanderburgh, in front of a specially invited audience in Tokyo. That's something that normally people don't see. It was an in-house thing."

The bonus DVD also presents seven performances, three versions of 'Love Ain't No Stranger' (music video, acoustic in Tokyo, and from the 'Live...In The Still Of The Night' DVD), two 'Guilty Of Love' (the music video and from the band's headlining set at The 1983 Monsters Of Rock festival), the 'Slow An' Easy' video and a 1984 Top Of The Pops clip of 'Give Me More Time.'

'Slip Of The Tongue,' the 1989 album featuring guitarist Steve Vai, went platinum. The deluxe version also includes six bonus tracks, the rare B-side 'Sweet Lady Luck,' alternate mixes of 'Now You're Gone' and 'Fool For Your Loving,' a live 'Judgment Day' and 1990 Live At Donnington versions of the title track and 'Kitten's Got Claws.'

Videos of the Donnington performances are also on the DVD, along with the music videos for 'Now You're Gone,' 'Fool For Your Loving' and 'The Deeper The Love,' and live from Tokyo 'The Deeper The Love,' as well as 'Sailing Ships' and 'Judgment Day' from the 'Live...In The Still Of The Night' DVD.

"It's a fine compendium for anybody who enjoys it, but the big thing for me is being able to bring the sound up to date," says Coverdale, "Earlier, when people did a simple transfer from tape to CD, nobody artistically was involved in it. It's a pretty straightforward thing, and I was always disappointed with the result, but this time we worked very closely with the Universal people, and I worked with EMI outside of America, to put a great package together. And as the artist, I'm thrilled with.

"It's just been out in Europe now for over a month and the response has been amazing from the hardcore fan, and that's a big deal for me," he continues. "And the other thing, of course, is the opportunity to remaster with modern technology. I have a great guy in Los Angeles who got an incredible sonic dynamic out of these old analog tapes."

There is the possibility for other reissues, but his record label, Universal, wants to see how these do, says Coverdale. "I've had the '87, which was my most successful album, that was released in Europe two years ago to celebrate the anniversary. I've turned into this anniversary kid, it's hilarious," he laughs. "This year, there was this 35th anniversary of Deep Purple's 'Stormbringer 'so that was another special edition that came out.

"I'm focused primarily on Whitesnake because that's been my baby for so long, and then, god willing, if these do well, then we'll bring out the '87 one, probably for the 25th anniversary. There's always some stuff to add to it, always a little bit of this and that."

Coverdale says Whitesnake's most recent album, 2008's 'Good To Be Bad,' made with the current touring lineup – Coverdale, guitarists Doug Aldrich and Reb Beach, bassist Uriah Duffy, keyboardist Timothy Drury and drummer Chris Frazier – hasn't been promoted properly.

"The disappointment with it was the European record company [SPV GmbH] we were working with went bankrupt, another sign of the times. We had committed to this tour at their request to promote the record in America because we did really well last year without promotion and, sadly, there's nobody to help us out there now. So I think we're going to make it available on iTunes."

Coverdale says he works on new songs on a daily basis, but won't get together with partner Aldrich, who is expecting a child, probably until Christmas "for a potential new project – if he isn't too exhausted."

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