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Author Topic: Velvet in film trap Thomas Jonsson Expert Film Handler Posts: 216 From: Bromolla, Sweden Registered: Sep 2003 posted 07-19-2005 12:09 PM                       The lamp is a 4 kWatt, slightly overfocused. The velvet on the tension bands isolates the film from the heat, and it works fine. Build ups are very rare. The bands I use are not really velvet, but some type of self- adhesive material I don´t even know the Swedish word for. They are thinner than velvet and very easy to clean. If brushed and cleaned regularly, do you still think velvet causes more wear on the film compared to running on metal only? Thomas  |  IP: Logged Miguel Garcia Film Handler Posts: 7 From: Santa Cruz/ Murcia, Spain Registered: May 2004 posted 07-20-2005 04:17 AM                  My personal opinion on this question is, that it would be due to replace velvet bands, by teflon bands. The properties of teflon imply that this material support the temperature very well, is, at the same time, little abrasive, and also has the particularitity of being very stable to the statics charges. With my greetings, Miguel García  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 07-22-2005 08:20 AM                        quote: Curved seating is more important if your auditorium is fan shaped (with seats not directly in front of the screen). Many modern multiplexes are built with wall to wall screens and rectangular auditoria. That's quite an interesting idea -- a surface material that has a very low friction coefficient. It would seem that the non-stick properties would prevent that very type of emulsion build-up (and burn-on) that is so often seen on bands and gate rails. The one issue which might prevent this application, at least on the bands, would be whether or not Teflon is a flexible substance or is it rigid and can only be applied to a hard substrate?  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 07-22-2005 09:07 AM                     The main problem with Teflon coating film bands is getting the stuff to stick to them. True, nothing likes to stick to Teflon but Teflon doesn't like to stick to anything else either. It's a long, difficult and expensive process to Teflon coat metal. First, the metal has to be acid treated and bead blasted to make the surface rough. Then an ultra thin layer of Teflon is sprayed (or somehow coated) onto the part and baked. After that Teflon is repeatedly layered onto the part and baked until the desired thickness is reached. When finished, the surface is not perfectly smooth, nor is it very durable. I can't imagine it would hold up very long as the film runs against it for hours on end. I figure that the expense of Teflon coated parts plus the expense of replacing them when the coating wears off would be prohibitive to say the least.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 07-22-2005 09:23 AM                     Go like kinoton and make the entire band out of delrin The only problem is if the film is cleaned with filmguard it will not produce a steady image no matter what you do (been there done it with dp75) The velvet also improves stability because the hairs engage the perf and act like little registation pins  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 07-22-2005 07:28 PM                     Bullshit Gordon. I am running a dozen Kinotons with delrin gates and each print is FilmGuarded on every show and they are producing images steadier than is possible from any other projector. Get your facts straight.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 07-22-2005 07:35 PM                     Film Guarding on a Kinoton delrin skate/runner system also seems to make them last nearly double as compared to non-Film Guarded theates.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 07-23-2005 08:35 AM                     "Bullshit Gordon. I am running a dozen Kinotons with delrin gates and each print is FilmGuarded on every show and they are producing images steadier than is possible from any other projector. Get your facts straight. " I have several DP75 in service and non will produce a steady picture if the print is treated yet are rock steady with out and you will notice i did specifie the DP75 THe FP 20's we use are all in post facilities so it has never been an issue  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 07-23-2005 04:43 PM                     You implied all Kinoton and then mentioned your experience with an DP75. So what's different about the gate design on a DP75 than the rest of Kinoton's line to cause this problem no other projector (Kinoton or non-Kinoton) has?  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 07-23-2005 06:03 PM                     I think but am not sure it is due to the multiple curves it has and the overshoot between them  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 07-23-2005 06:22 PM                     Oh...the DP75 gate is indeed a strange one! You will wonder what someone was thinking when you see the "path" the film must take. It enters the gate like a Century SA on a "back flip" it is immediately guided by delrin but the curve is concave towards the lamphouse so the film starts traveling back toward the lamphouse as it moves down to the aperture (pretty aggressive radius). Tension is applied at this stage too. As it enters into the aperture area, the runners remain delrin but the "skate" area transistion to metal (I don't know the material off hand). It the film moves almost straight down in this area, almost like a stright gate (this area is about an inch and a half long. The film then starts heading back on an mirror image of its entrance with delrin on the rear with the runner once again concave towards the lamphouse (the skate just stops at this portion so you can see the film exiting the gate prior to entering the intermittent). The film exits the gate via the intermittent with the film heading forward like on a AA2. I'm guessing they were trying to design the gate/skate such that it naturally tensioned the film without the normal tension bands or merely pushing the film harder against the runners. There is a tension adjustment that applies more tension to the film at the top where it enters this contraption. Sound strange? It is...I wish I had a good photo of it to show you.  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 07-23-2005 08:42 PM                     FP-75, my least favorite projector from generally a great manufacturer The last two I had to deal with where replaced with V-8/35-70 with SLH 5 kw lamphouses ( pair of ORC 4500 removed from service ). The result 250% increase in light output and rock steady image. Made the judgement call based on service records, parts cost and lack of some accessory upgrades for the existing machines. Velvet for gate runners have their issues....outside of use in Ernemann products, we have used them in some laboratory and library archive screening room projects. I was one of the intital users of the V-5 curved film gate and dirt sticking to the bands became an issue...I am glad they have a fix for this. The band material behaves as something between metal and plastic composition and is thin compared to a typical Century SA gate unit, the last time I played with them.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 07-23-2005 09:09 PM                     I actually run a pair of DP75s on occasion...strange as it may sound...I like them and they put on a good picture. They are used very infrequently and are in a small screening room.  |  IP: Logged Matthew Taylor Expert Film Handler Posts: 186 From: Essex, UK Registered: Mar 2004 posted 07-24-2005 05:41 PM                     Well, Just to let you know hoe I got on... I have been testing a couple of different types of velvet bands. Clive Carmock kindly sent me some kinoton velvet, but that created focus issues. I next tested the velvet strips that Thomas Jonsson kindly sent me. They are thinner than the Kinoton velvet and worked better. I got slightly better picture steadiness and a slight reduction in noise. I disdn't have to use much, if any, tension on the bands with the velvet. The big drawback is that using velvet seems to make the aperture plate act like a dust magnet. Would this be to do with static? Anyway it doesn't take long for the aperture to get big buildups of dust at the bottom (top on screen).  |  IP: Logged Miguel Garcia Film Handler Posts: 7 From: Santa Cruz/ Murcia, Spain Registered: May 2004 posted 07-25-2005 05:32 AM                  To Matthew Taylor, Your projector has a very important problem with static load. The velvet bands increases the referred problem still more. The friction of the film on the velvet, behaves as a real magnetic generator, and that is why the particles adhere easier to the velvet. If you allow me, I suggest you to increase the level of relative humidity of the air in your projection room. Also, you must clean frequently, with an antistatic cleaner, all the metallic parts of your projector which are exposed to the film running; you can use for this purpose any of the products authorized for the cleaning of video heads. The isopropílico alcohol also can be used for cleaning and desmagnetization. If you fulfill these instructions in a periodic form, verified that every time less particles were accumulated in your projector. With my greatings, Miguel Garcia  |  IP: Logged

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