8mm Forum: Paste or Laminated Stripe?

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Posted by Simon McConway (Member # 219) on January 02, 2006, 07:28 AM:

E v T can apply laminated stripe (magnetic tape material "welded" chemically to the film) or paste stripe (as I understand it, a magnetic paste which forms the track). Has anyone tried both? If so, which is best? I have only tried laminated stripe, so far.

Posted by Maurizio Di Cintio (Member # 144) on January 04, 2006, 04:40 AM:

Years ago I heard that paste stripe is more abrasive than laminated. Apart from that I think it is impossible to tell whether a film has paste or laminated stripes based on listening, provided the paste has been properly smoothed (to avoid drop-outs etc).

Posted by John Whittle (Member # 22) on January 04, 2006, 09:09 AM:

It was claimed that the laminated stripe was flatter, provided better head contact, was flatter in the gate and had smoother edges and thus less head wear.

The downside was that laminted material was more expensive and thus professionally (35mm four stripe stereo prints, 70mm prints and commerical 16mm prints) were all paste or dispersion stripe when a liquid is placed on the film and then cured and hopefully "polished" for flatness.

Today, if you have a choice, I'd opt for laminated. The true laminated material (made by Agfa-Gevaert and 3M) had a thermoplastic adhesive and then the acetate "carrier" was stripped off the stripe leaving just the magnetic material and thermo plastic adhehsive on the film. Most home rigs just used a slit commerical acetate recording tape and "glued" it in place with a type of film cement. This method has resulted in buckles and delamination. I personally have never seen a failure of the true thermoplastic stripe but there wasn't alot of that done in the first place.

John

Posted by Tim Christian (Member # 48) on January 04, 2006, 11:02 AM:

There are a couple of requirements for successful laminated stripe:

- adequate adhesive supply
- ensure that stripe remains on the film between laminating and reeling
- leave freshly striped film on its reel for 24 h so that all solvent evaporates.

Cleanliness, stripe and film tension are all, of course, important factors in preventing delamination, but those highlighted factors are often overlooked. Finally, check between rewinds that there is no looping of stripe over joints: tedious but essential. Have a fine brush and adhesive ready to stick errant loops down, then leave on reel as before.

Posted by Paul Adsett (Member # 25) on January 04, 2006, 09:35 PM:

Another question for the stripe experts: why is some stripe a rust colour whereas others are black, and which is best?

Posted by John Whittle (Member # 22) on January 05, 2006, 12:34 AM:

The color of the stripe depends on the formula used by the striper. The liquid dispersion stuff was mostly the brown rust color since it's main ingrediant was Pyzers (sp?) magnetic oxide.

The darker and black stripes were usually from magnetic tape which used any number of forumlations as commonly found on 1/4 inch audio tape and cassettes.

One point about quality is the requirement of the proper bias for the stripe you're using. There are laboratory methods of determining that and profession equipment has adjustments for bias current for various types of magnetic media. Not really something you can do at home, but a common part of professional recording. For years the 3M 111 tape was the standard and other tapes were judged against it and bias currents and frequency response were set with the 111 tape as a standard.

I remember going to an auction in Los Angeles for one of the last magnetic stipe companies when he shut down unable to afford all the air scrubbing equipment required. He mixed his own stripe and had reels of old video tape and other "magnetic tape scrap" that we'd thru into the brew when making up his dispersions. That's also where I saw all the bags of the magnetic oxide.

Another major striping company was Magnacraft which was a division of Technicolor. They had shut down in the early 1990s. They also mixed their own liquid dispersions materials. The entire operation was a three man outfit. The other striping lab for motion picture prints was Deluxe which did their striping at the Fox Studios in Beverly Hills. Between Technicolor/Magnacraft and Deluxe, they turned out all the 35mm and 70mm magnetic sound release prints in the US.

John

Posted by Jean-Marc Toussaint (Member # 270) on January 05, 2006, 07:35 AM:

Wow, fantastic informations lads...

From an amateur view-point, I have been re-recording some recent prints that feature (pun intended) "liquid" stripe without any loss of quality. Then again, I might have been lucky.
But I have heard horror stories about early versions of this material, melting away under lubricant products or simply falling in dust inside the projector.
The only problem I ever encoutered was with an old silent L&H print purchased many moons ago. It had been badly "striped" and I spent hours cleaning my Silma, removing miles of spaghetti magnetic soundtrack.

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