Videomaker – Learn video production and editing, camera reviews › Forums › General › Video and Film Discussion › Recurring Dirty heads. Old tapes – do they ruin your camera? › The idea that the lubrican
The idea that the lubricants on different tape brands will cause problems for your camcorder is, at best, a theoretical problem. If the lubricant is a problem, it is due to that tape damaging your tape path. There is not a lubricant that comes off or adheres to something other than the tape. (Come on, think about it. If there was required lubrication that wears off, tapes would have a maximum number of safe passes.) The lubricants are bonded to the tape itself & you’re screwed if any of it comes off, EVER.
Next to the black striping. Why? When using an analog editing system, most folks would black stripe the tape so they could insert edit and not encounter the editing problems associated with a broken control track. Now most of you have no idea what I’m talking about since none of this has the least thing to do with non-linear editing. Black striping your tape before recording does nothing except add wear to the tape and your recording unit. The entire concept of insert editing doesn’t exist with NLE’s.
However it is an excellent idea to retension any tape before you use it. Retensioning the tape consists of fast-forwarding to the end & rewinding it back. You do this make sure the is evenly tensioned on the take-up and rewind spools. During shipping & such, the tapes are bounced around and tighten unevenly on the spool. You could actually see the uneven tension areas on long VHS tapes. It looked like darker & lighter bands of the tape on the reels. Retensioning them eliminates the banding and insures the tape will spool out easily and evenly from the start till the end. To some extent, I also believe this might be a theoretical issue. But I have encountered times when a new untensioned tape stops without any apparent reason. And that has never happened to a tape I knew was retensioned.
And folks, these tapes are not “dirty” or coated with anything. What is causing problems is the fact that your video head is magnetic and you are physically rubbing oxide particles on the tape across it to read & write data. So there is no way to stop a certain amount of build-up of oxide on & around the tape heads. Now a lot of folks don’t seem to realize just how big a video head is. The heads on our camcorders are just over half the size of the italic I in the reply box. The are far smaller than even the point of a number 2 pencil you’ve written with. The heads are embedded in the large silver drum that spins rapidly. If you could touch them (DON’T TOUCH THEM) they are the tiniest bit higher than the surface of that silver drum. The notches cut into the drum are better than four times the size of the head. That provides a bit of space for loose oxide escape instead of getting jammed onto the actual head. Back in the days of VHS, when the heads were a bit larger, I worked out the math of video tape recording. It looks like nothing has changed except for the size, so the heads are being spun at 3,600 RPM or 600 revolutions per second. VHS tape (in SP) runs at 1.5″ per second. So the video head is putting 600 lines on the tape in every 1.5″ and there are two heads, each writing or reading lines, making 1,200 lines in that 1.5″ Or roughly 800 lines per inch of magnetic data on an oxide coated plastic tape. So the focus of those video heads is to an area far smaller than we can hope to see.
Knowing this helps to understand what is happening at the interface between the video head & the tape. At this level, the video heads are stumps with a metal oxide sandpaper screaming across them. Sandpaper with bigger particles are easier/cheaper to make, but big particles make rough sandpaper. Rough sandpaper breaks off chunks from the tape. Fine sandpaper will polish the heads, but it is still rubbing off bits off bits of its coating. So cheap, off-brand tapes are going to leave more oxide behind, than higher quality tapes from a reliable source. There is a rapid diminishing of differences between moderately priced tapes & expensive tapes as far as the qualities effecting the physical wear & tear of the tapes. Top line tapes are a bit more sturdy and have more exotic oxides on them. But the bonding of the oxide to the plastic backing doesn’t really improve in a practical sense. But that still means that some oxide will wear off the tape and stick to what wore it off, the video heads.
If the oxide that is rubbing off hasn’t built up too much around the edges of the head, you can use a dry cleaning tape to sand off the oxide and bring playback back to snuff. The wet tape would be needed if there was a bigger build up and you needed a solvent to loosen the oxide on the video head while scrubbing with a scratchy scrubber. And to be honest, both methods are wearing down the heads with the rough tape surfaces and they only clean in the same directions as the tapes that put the oxide there to begin with. So for an amateur video shooter, they should work just fine.
But for the kind of hours even a semi-pro runs tapes through their machines, cleaning tapes are far too abrasive. You need to be cleaning the heads properly. And it ain’t happenin’ if you’re standing there with a q-tip and a bottle of rubbing alcohol. You may as well use a cleaning tape. To actually clean the heads without damage, go down to Radio Shack and purchase a chamois swab with tape head cleaner. Be very careful with head cleaner, it will evaporate away if you don’t keep the lid on it. Basic head cleaning is fairly straightforward. You open up the door and you will see the silver drum with lines cut into it. There are generally four heads on the bottom edge of the drum, which is tilted slightly. If you can’t reach in and stabilize the drum from the top (and who can?) you can use a brand new soft pencil eraser to press down on the top of the drum to hold it in place once you rotate one of the heads into place. Dampen your chamois swab in the tape head cleaner, press it against the video head & rock it lightly, pull it back and press it against the head again. If the head was really built up, you might be able to see a black spot on the clean chamois. Do the same on all the heads and you’re good to go.
Now that you know what’s going onto the heads, we can discuss how it happens. We need to consider the conditions that degrade the binding of the oxide to the plastic backing. Cheap materials are pretty obvious candidates. But age, especially in poor conditions, is a double whammy on tape. Most plastics lose flexibility as they age. As do the binding agents, so when the tape is threaded through all the loops & whorls of the system, all that flexing “cracks” the tape and oxide flakes off. Another factor I’ve heard about but haven’t encountered is tape from another continent. But there is certainly the factor of aging in less than ideal conditions during the shipping. Aging is the factor that really improves with higher quality. Kept in their specified conditions, the best tapes can last nearly a decade. But the sort of tapes readily available to most of us are going to age more rapidly. And the net effect of aging is that microscopic cracking that happens as the tape does the M thing into the deck. Oxide flakes off more easily by the direct pressure of the video head and so they build up a coating quite rapidly. That is what causes the dreaded “blue screen.” The video heads can’t read the signal on the tape because they are covered in oxide and can’t detect a signal anymore.
So your problem sounds like you’re getting the tapes folks have had around for a while and want to get on something convenient. Tapes only two or three years old from unknown sources could already be in an aged, microscopically brittle. Doing a retensioning would help, but the more flex you can get before running it over your heads would help a bit. And these oxide flakes from aging build a layer over the head. You have to use the proper solvent to “melt” the flakes off. You have to use the highly volatile tape head cleaner and, at least, the artificial chamois. You can clean your own heads properly and be able to transfer off another three or four tapes before you clean them again. At least that’s how my engineer taught me.
Good luck, you’ll never regret learning to clean your video heads.