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Daan and CCP4ers Douglas Instruments is also very happy to give refunds to people who have bought the tape that goes cloudy. I only have a few comments, about the plastic used to make the tape. The brilliant thing about the original Crystal Clear tape was that it was made of polypropylene which is a very good barrier to water. With 2 layers of CC tape you lose roughly the same amount of water through the body of the plate as through the tape - about 0.1 microlitres per well per day. (With one layer, rather more goes through the tape.) As you can see from the table below, polypropylene is far less permeable to water than most other plastics used for tape: The first number is the water vapor transmission rate for a 25 micron layer, (units are g/m2.d (38C 90% a.r.h.)) The second number is oxygen transmission rate for a 25 micron layer (cc/m2.d.atm) Cellulose >1000 10 Polycarbonate 150 3500 Polyester (PET) 20 50 Polypropylene 12 3000 Polystyrene 170 3500 PVC >200 >2000 You can see that polypropylene is much the best water barrier of these common polymers. Most other really clear tape that I know of is not polypropylene. Interestingly, regenerated cellulose (cellophane) is a very good barrier to oxygen. This may be of interest to all those working with oxygen-sensitive proteins! Regards Patrick Shaw Stewart -- [EMAIL PROTECTED] Douglas Instruments Ltd. DouglasHouse, EastGarston, Hungerford, Berkshire, RG177HD, UK Directors: Peter Baldock, Patrick Shaw Stewart, James Smith http://douglas.co.uk or http://www.douglasinstruments.com Tel: 44 (0) 148-864-9090 US toll-free 1-877-225-2034 > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bob > Cudney > Sent: 14 October 2005 19:16 > To: Patrick Shaw Stewart > Subject: RE: [ccp4bb]: (off-topic): Tray Tape Trouble > > *** For details on how to be removed from this list visit the *** > *** CCP4 home page http://www.ccp4.ac.uk *** > > > Daan: > Cc: ccp4bb > > No Daan, we are not happily shipping bad tape. In fact, we are as > bummed as you and everyone else using this tape, as we use it every day > in our own crystallization lab. > > Here's the scoop. > > CrystalClear Sealing Tape (Hampton Research catalog HR4-510) has been > used for protein crystallization since 1987 when Alexander McPherson > first visited a hardware store in Riverside, California and bought a > roll of Manco crystal clear carton sealing tape to seal the original > Cryschem plate, and then made by Cryschem. This tape was and is nothing > more than carton sealing tape. This tape has been used successfully > without clouding since that time. It is noteworthy to mention that > other carton sealing films made by other vendors did and do produce the > clouding. Only the Manco made tape could be used for crystallization > without clouding. This tape was originally made by a private, USA based > company called Manco. The CrystalClear Sealing Tape was made in the > USA. In recent years Manco was acquired by the very large consumer > products firm, Henkel. > > In recent weeks we noticed in our own crystallization lab that the > CrystalClear Sealing Tape would cloud over certain reagent reservoirs. > We immediately pulled the tape from inventory and stopped shipping the > tape. Upon inspection we found two lots of tape in inventory. One lot > worked as it should, the newer lot produced the clouding problem. We > returned the older lot to inventory and have been selling that tape. > The last roll was sold today. As of today there is no more 2 inch wide > CrystalClear Sealing Tape in inventory at Hampton Research. > > For those reporting problems with the tape, Hampton Research has been > offering a replacement for the 2 inch film from the old lot or a credit, > a refund or what ever is needed to make things right. > > Hampton Research has been in communication with Henkel about the > CrystalClear Sealing Tape. Mind you, this is a David and Goliath (a > nice goliath) situation as Henkel is a multi-billion dollar/Euro/pound > consumer products company and this tape is simply a tip of the iceberg > for their business. Hampton Research has sent samples of both lots, > before and after testing with crystallization reagents to Henkel for > evaluation. Unfortunately Henkel has not yet evaluated these samples > and has no comment at this time. Hampton Research has purchased and > tested three of the most recent lots of CrystalClear Sealing Tape from > Henkel and has found all these lots produce the clouding effect. This > tape was donated to those interested in sealing cartons and not plates. > Henkel has supplied samples of other tapes to Hampton Research for > testing. Only one tape performed in an acceptable manner. However, > this tape is not supplied on the popular 2 inch diameter roll with the > green dispenser/cutter. It is only available on the larger 3 inch > diameter roll without a dispenser/cutter. This makes dispensing and > cutting less than convenient. This film is made from a slightly thicker > film material and the optics are not quite as good as the original > Crystal Clear Sealing Tape, but they do allow viewing of the drop. > Hampton Research has ordered this film and will offer it as a possible > substitute for the original 2 inch wide CrystalClear Sealing Tape. The > catalog number for this new film will be HR4-511. > > At this time the 3 inch wide file (catalog number HR4-506) and 4 inch > wide (catalog number HR4-508) still work without clouding. However, > Hampton Research is concerned that future lots may produce clouding and > is testing each new batch of film that arrives. > > Why? > > Based on our discussions with Henkel it appears that Henkel has out > sourced the production of the CrystalClear Sealing Tape. Henkel has > manufacturing specifications to which out sourced firms must adhere (pun > intended) by the out sourced manufacturing firms. That the film remains > clear when placed over crystallization reagents is not one of these > specifications. The chance of this specification being added to the > requirement is of course quite slim as Henkel cannot afford to be > worried about a few thousand rolls being used for crystallization when > millions are rolls are used to seal cartons. Anyway, it seems the > adhesive formulation has been changed. Perhaps a cost cutting measure, > how knows. The film still seals cartons but now clouds over > crystallization plates. The 2 inch wide film is a consumer product and > sells much more rapidly than the 3 inch and 4 inch wide film. Hampton > Research and Henkel feel this is why the 3 inch and 4 inch tape remains > unaffected since there remains old inventory at Henkel and the new lots > of material have not yet been produced. > > Hampton Research is continuing to work with Henkel to better understand > the problem and see if there is a chance to obtain the original 2 inch > wide CrystalClear Sealing Tape on the green dispenser/cutter. Or > perhaps find a suitable substitute beyond what will soon be offered (see > above). > > So that's the story. > > In summary, right now it seems the 2 inch wide CrystalClear Sealing Tape > from Henkel/Manco has changed and clouds when placed over water or > crystallization reagents. The 3 inch and 4 inch are okay at this time. > As Daan stated, there is another film, produced by 3M and sold by > various plate and crystallization vendors (including Hampton Research) > under various names that works fine as a optical quality seal for > crystallization plates. This film is available on a roll or in sheets > cut to fit SBS sized crystallization plates such as those made by > Corning, Greiner and Art Robbins. This film, a special, silicon based > non-tack, pressure sensitive film, being a specialty film is more > expensive than the CrystalClear Sealing Tape, which is/was, simply a > carton sealing tape made for the mass, consumer market. > > Way too much information. But we wanted to let those interested know > what is going on as of October 14, 2005 with the CrystalClear Sealing > Tape. > > Kind Regards, Bob Cudney - Hampton Research > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of > Daan van Aalten > Sent: Friday, October 14, 2005 9:14 AM > To: ccp4bb@dl.ac.uk > Subject: [ccp4bb]: (off-topic): Tray Tape Trouble > > *** For details on how to be removed from this list visit the *** > *** CCP4 home page http://www.ccp4.ac.uk *** > > > > Dear all > > Has anyone noticed that Hampton and Douglas have recently changed their > crystal clear tape? The adhesive on the new tape reacts with water and > goes cloudy - thus making it very difficult to look at the drop. > Apparently Hampton and Douglas are aware of this, but are still happily > sending out these new (and unusable) rolls. > > Does anybody know where we can get tape that is good for crystallography > purposes ? Apparently Abgene sells tape that can be used but this costs > 1500 GBP for a 250 m roll. > > cheers > > Daan > > ################################################################## > ###### > ###### > Dr. Daan van Aalten Wellcome Trust Senior Fellow / > Reader > Wellcome Trust Biocentre, Dow Street TEL: ++ 44 1382 344979 > Div. of Biol.Chem. & Mol.Microbiology FAX: ++ 44 1382 345764 > School of Life Sciences E-mail: see WWW page > Univ. of Dundee, Dundee DD1 5EH, UK WWW: > http://davapc1.bioch.dundee.ac.uk >
