HauteHippie Posted March 20, 2007 Report Share Posted March 20, 2007 AR Coating Reference Thread Many of you now know that a group of forum members recently sent off some of our watch crystals to a professional optics laboratory for anti-reflective coating. You can see pictures of the results in threads such as this one: http://www.rwg.cc/members/index.php?s=&...st&p=217535 Here are a couple: Many people are now expressing interest in coating their own crystals and have sent me PMs, so I'd like to use this thread as a reference which contains everything I now know (and potentially alot more than you ever wanted to know) about AR, the process, the pricing, etc. Here it goes... The Coating Not all AR coatings are equal. The performance and durability of the coating can vary dramatically based on the type of coating and how it is applied. I have found an optical coating company that provides coatings for high end watch and sunglass manufacturers, and there are two viable options for coating watch crystals using their facilities: (A) A durable single layer coating that can be applied to one or both sides of a watch crystal. This coating is applied inside a vacuum chamber at temperatures of approximately 550 degrees F or 290 degrees C. Because of the extreme conditions in the chamber, we can not coat crystals with cyclopes attached double sided because the crystal glue will melt and most likely smear across the surface of the crystal (See Option B for coating crystals with cyclopes). The durability of this coating is derived from the high temperature at which it is applied and it meets US Military Specification MIL-C-675 for durability. MIL-C-675 specifies that the coating will not show degradation to the naked eye after 20 strokes with a rubber pumice eraser. MIL-C-675 coatings can be cleaned repeatedly and survive moderate to severe handling. They will not, however, resist scratches in the same way as uncoated sapphire. If you do not use common sense when cleaning the coated crystal, you CAN scratch the coating. The durable nature of this coating means that it will be extremely difficult, and possibly impossible to strip it off the crystal through an acid wash process. So once it is applied to a crystal, it's there to stay. ( A non-durable single layer coating that can be applied only to the inside surface of a watch crystal. This coating is applied inside a vacuum chamber at room temperature. The result is a coating which can NOT be touched or cleaned. Extreme care must be taken when handling and reinstalling the watch crystal. However, because this is a room temperature process, it should allow us to coat crystals with cyclopes attached. There is still a risk that a poorly installed cyclopes (for example one with air bubbles in the glue joint) could fail inside the vacuum, and that the cyclops might pop off. This coating can be stripped through an acid wash process. Both coatings used in A and B are the same chemically. So, both have a slightly bluish tint. Both provide <1% reflectance on the coated surface (compare to roughly 4% reflectance off an uncoated sapphire surface). The Machinery The crystals themselves must be secured inside the coating chamber in some fashion. For the durable high temperature coating this is done using two parallel straight rails that sandwich the crystal and secure it inside the machine. These rails have a small lip which rests on top of the surface being coated. The lip measures 0.035" or 0.8mm nominally. Because the rail lips must overlap the face of the crystal to secure it in place, there will be two small sections of the crystal 180 degrees apart which do not receive any coating. We'll call these uncoated sections "lip marks". Most lip marks will be a bit less than 0.035" because the coating company is able to clamp the crystals down slightly loose in the machine. This is the nature of the beast and is going to be the case at any coating company who performs high temp coating. The metal rails will expand and contract more than any other material at the high temperature. So without the lips, the rails would expand more than the crystals, and the crystals would come unclamped and probably be destroyed. For the non-durable single sided coating, we can avoid lip marks by requesting that the coating company use double stick tape to secure the crystals in the chamber. This tape would melt at high temperatures, so it is not an option for the double sided coating. Fixtures For Genuine Watches You might be wondering whether or not AR coated crystals on genuine watches have these lip marks. The answer is yes and no. To coat crystals for watch manufacturers, custom fixtures are designed. These custom fixtures are circular and completely surround the crystals, as opposed to the parallel rails that we need to use. The coefficients of expansion and contraction can be precisely determined since they're dealing with the same crystals over and over and over. Essentially they know much better what they're able to get away with, so therefore they are able to design crystal fixtures of precisely the right diameter and with lips of only about 0.025". The end result on a coated crystal for a genuine watch is that the lip mark encircles the entire crystal rather than being only at two sides 180 degrees apart as on ours. For anyone mechanically inclined, there is a patent opportunity in designing an adjustable radius circular fixture for coating watch crystals of variable size. ;-) Pictures Of Lip Marks Here are a few pictures of lip marks. In order to see them with the naked eye, you have to be looking at just the correct angle to see the coating. They are difficult to photograph, but here's what I've been able to capture. The red arrows point to the lip marks. The Process Because of there being a potential for mistakes by the coating company, we'll be separating AR Runs into two: (1) Double sided durable no-cyclops coating runs; and (2) Single sided non-durable cyclops or no-cyclops coating runs. Sign-up threads will be posted to the Repair and Upgrade section of the RWG forum. Once 20 commitments are made, I will assign numbers to each crystal. Then each participant of the AR run will send me (chieftang) the crystals labeled with the provided number, which side (or both) to be coated, their forum name, their real name and return address, and a cashier's check or money order (from a bank or US Post Office -- not a liquor store) for $40 USD per crystal. Once all the crystals are received, I will measure each one with dial calipers, package them individually with instructions for the coater, and ship them off. The coating process can take anywhere from 1-3 weeks, not including transit time to and from the coater. Once the coating is complete and I've received the coated crystals back from the coater, I will remeasure them to confirm that I return the right crystals to the right people, package them up and ship them back. Logistically speaking, it is probably a 6 week process from the time you ship until the time you receive a coated crystal. Unforeseen circumstances could alter this time frame. I will provide up to the day status at each phase of the project to all participants through PMs. AR Stripping I will not accept crystals that have an existing AR coat on them. If you wish to try stripping the light replica AR off a crystal that is up to you, but do not send me any crystals that still have existing AR remnants. I have successfully stripped a replica AR coat off a Seawolf Avenger Ti crystal. This wasn't what I'd call "light AR" - it was a deep blue color and fairly thick. But compared to the professional coating, it wasn't what I'd call good AR, either. In any event, here's what you need to strip an AR coating: Paint respirator ($20 link), Lacquer thinner ($6 link), Stripping gloves ($3 link), #0000 steel wool ($5 link). With the respirator on your face and gloves on your hands, simply apply the lacquer thinner directly to the crystal and to the steel wool pad, and then rub until the coating is gone. Be sure to check the edges and keep working at it until all remnants are gone. It shouldn't take more than 5-10 minutes. You may have to wet the crystal and wool pad with more thinner a few times. Be forewarned that if your crystal is not sapphire, it could scratch. I think (but don't know for sure) that my crystal is mineral, however it did not scratch at all. Last but not least, be sure to properly dispose of any rags, steel wool, etc that you've soaked with lacquer thinner. Do not bunch them up and toss them in the trash - they can spontaneously ignite and cause a fire if you do this. Soak them in water and drape them over something outdoors to dry. I can't make any guarantees that this will work for everyone, but the ease at which it removed my coating makes me think it should work on most coatings. I also intend to get another sample from the AR company to try stripping using this method just to see if it can remove the Mil Spec coating or not. The Group Pricing The magic number of crystals needed to initiate a run is 20. Pricing is $40 per crystal. The $40 includes: The AR coating (single or double sided), the cost of unregistered air mail return shipping with delivery confirmation (delivery confirmation is only available in the US), the cost of shipping to and from the coating company, my time in unpackaging (twice), measuring (twice), repackaging (twice) all the crystals. Optionally, you may want to pay extra for the following: insured return shipping (+$3 per $100 of coverage), priority return shipping (+$5), registered return shipping (+$10 and up), international EMS shipping (+$30, the only way to obtain a tracking number for international shipments), etc. All prices are in USD. I will accept paypal payments for non-USA members who are unable to obtain bank cheques in US Dollars, but you will cover my paypal fees. You will also understand that the run will be delayed for a week to ten days while I wait for the check from paypal to arrive in the mail. The cost per crystal will be $42 USD if paying through paypal. You will also have to add an additional 3% to the cost of any shipping upgrades (express, priority, etc) as well. See examples. Examples: One crystal for coating to be return in US paid by check would cost: $40 USD Two crystals for coating to be returned to Canada via EMS paid by paypal would cost: $42x2 + $30x1.03 = $114.90 USD Three crystals for coating to be returned to EU via unregistered air mail paid by paypal would cost: $42x3 = $126 USD Installation Of Coated Crystals (A) If you're installing a double sided (durable) coated crystal, simply place a polishing cloth between your crystal press die and the crystal to prevent marring of the AR coat, and then press it into place. You can use a polishing cloth to wipe the interior suface clean prior to installing, if you feel this is necessary. Air should be good enough. ( If you're installing a single sided (non-durable) coated crystal, take extreme care to not touch the crystal with your hands prior to pressing it back in to place. Oils from your fingers will permanently ruin this coating, so use rubber gloves or finger cots to handle the crystal. Only hold the crystal at the edges. Do not touch the coated surface, even with gloves, a cloth, etc. Use only air to clean it. Be very careful when setting the crystal back into place and be sure that the coated surface doesn't rub against the watch. Disclaimers As with any modding project there are risks involved. All risk is borne by the individual participants and not by me. I am not responsible for any damage that occurs to any crystals during shipping, coating, or any other phase of this project. I am not responsible for any mistakes made by the coating company. Your satisfaction is not guaranteed. I've shown pictures of actual crystals that have undergone this coating process already. If you like what you see, feel free to participate in a future run. If you are unsure, then please do not participate. If you have any further questions, please ask. 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cornerstone Posted March 20, 2007 Report Share Posted March 20, 2007 Awesome source of information - thank you!! Quote Link to comment Share on other sites More sharing options...
Guest avitt Posted March 20, 2007 Report Share Posted March 20, 2007 Great post! Much appreciated Quote Link to comment Share on other sites More sharing options...
sssurfer Posted March 20, 2007 Report Share Posted March 20, 2007 Thanks Brian. So, in the end even I had come to learn something about AR. Quote Link to comment Share on other sites More sharing options...
stockey Posted March 20, 2007 Report Share Posted March 20, 2007 Cheiftang,i also have the VC overseas,the maltese cross on your dial looks is much nicer than mine,did you do anything to it ? Quote Link to comment Share on other sites More sharing options...
Bignasty Posted March 20, 2007 Report Share Posted March 20, 2007 When you start the next run count up do keep us updated. The work you've done is greatly appreciated! Quote Link to comment Share on other sites More sharing options...
b16a2 Posted March 20, 2007 Report Share Posted March 20, 2007 Great information!!I will defnitely be interested in the next run! Quote Link to comment Share on other sites More sharing options...
Rob1 Posted March 20, 2007 Report Share Posted March 20, 2007 How would I strip existing AR from a crystal? I believe that a couple of the Breitling reps I own have "light AR" coating on them already, and I would like to get these coated with the double-sided AR. Is it easy to strip off the existing coating? Is it possible to raise money orders or bank checks from a UK bank that would be acceptable in the USA? It would be helpful for your overseas customers if you could set up PayPal or Moneybookers account (although I appreciate that is a lot of hassle). Thanks for offering this service Quote Link to comment Share on other sites More sharing options...
fotoman Posted March 20, 2007 Report Share Posted March 20, 2007 now there is a post of the month if i have ever seen one. great thread, great job, chief you are the man!!! you may want to touch on saphire/ mineral glass/ acrylic if there are any differences for folks wanting the service Quote Link to comment Share on other sites More sharing options...
trunk21 Posted March 20, 2007 Report Share Posted March 20, 2007 now there is a post of the month if i have ever seen one. great thread, great job, chief you are the man!!! you may want to touch on saphire/ mineral glass/ acrylic if there are any differences for folks wanting the service Absolutely. Thread of the month to be sure! Great work chief. Quote Link to comment Share on other sites More sharing options...
Pugwash Posted March 20, 2007 Report Share Posted March 20, 2007 Is it possible to raise money orders or bank checks from a UK bank that would be acceptable in the USA? It would be helpful for your overseas customers if you could set up PayPal or Moneybookers account (although I appreciate that is a lot of hassle). If I go ahead with my UK-based crystal removing/installing service for the next AR coating run, I'll offer MB and PP as part of the service. Quote Link to comment Share on other sites More sharing options...
Rob1 Posted March 20, 2007 Report Share Posted March 20, 2007 If I go ahead with my UK-based crystal removing/installing service for the next AR coating run, I'll offer MB and PP as part of the service. Quote Link to comment Share on other sites More sharing options...
crystalcranium Posted March 20, 2007 Report Share Posted March 20, 2007 Wow! Fabulous, informational, professional....everything I come to RWG for. Thanks so much for the great reference. Quote Link to comment Share on other sites More sharing options...
Pugwash Posted March 20, 2007 Report Share Posted March 20, 2007 Wow! Fabulous, informational, professional....everything I come to RWG for. Thanks so much for the great reference. I agree. This'd be PoM any month. Quote Link to comment Share on other sites More sharing options...
coolfire Posted March 20, 2007 Report Share Posted March 20, 2007 I agree. This'd be PoM any month. I second that!! :thumbsupsmileyanim: Quote Link to comment Share on other sites More sharing options...
RWG Technical Posted March 20, 2007 Report Share Posted March 20, 2007 Great post, I know more about AR coatings that I ever did. Well done. RG Quote Link to comment Share on other sites More sharing options...
HauteHippie Posted March 20, 2007 Author Report Share Posted March 20, 2007 Guys, thanks for your kind words. As far as stripping goes: it's not black and white. I've read some accounts of people having success stripping AR of genuine watches with acetone, a rag, and a lot of elbow grease (read a lot of work). During the previous run, I did ask the coater to strip an existing coat off my Breitling Avenger Ti. Stripping is a service they offer. However, it was only partially successful. So I've now got a crystal that is ruined, however I'm going to try my own hand an finishing the job with lacquer thinner and/or naptha. We'll see what happens. Regarding paypal / moneybookers... The issue here is mainly that this form of payment will delay the run. Basically I take all the received bank checks to my bank and have them draft a single check made out to the coating company. So if you're paying by paypal, then I have to request a check from them (I don't let paypal have my real bank account # for electronic transfers), wait for it to arrive, and then take it into the bank with all the other checks. I did do this for a couple EU members last time, so am not totally opposed to it. But it isn't preferable. I understand it might be unavoidable. What about Western Union... Will they draft a check redeemable in the USA? Quote Link to comment Share on other sites More sharing options...
Rob1 Posted March 20, 2007 Report Share Posted March 20, 2007 As far as stripping goes: it's not black and white. I've read some accounts of people having success stripping AR of genuine watches with acetone, a rag, and a lot of elbow grease (read a lot of work). During the previous run, I did ask the coater to strip an existing coat off my Breitling Avenger Ti. Stripping is a service they offer. However, it was only partially successful. So I've now got a crystal that is ruined, however I'm going to try my own hand an finishing the job with lacquer thinner and/or naptha. We'll see what happens. What happens if an existing light AR coating is not removed? Quote Link to comment Share on other sites More sharing options...
crystalcranium Posted March 20, 2007 Report Share Posted March 20, 2007 I'm going to try my own hand an finishing the job with lacquer thinner Well if this doesn't work, I don't want to know. Lacquer thinner is the most incredible stripper, cleaner, universal solvent I have ever used. I've cleaned brushes that have dried stiff with polyurethane to like new condition. In my repair tool kit, there's a Vicegrip, a roll of duct tape, and lacquer thinner! Quote Link to comment Share on other sites More sharing options...
HauteHippie Posted March 20, 2007 Author Report Share Posted March 20, 2007 I have high hopes for the lacquer thinner. My only question is whether or not the crystal itself will survive. The coating company will reject a previously coated crystal and send it back uncoated. BTW, I've added a section to the original post about installing the coated crystals... Quote Link to comment Share on other sites More sharing options...
crystalcranium Posted March 20, 2007 Report Share Posted March 20, 2007 I have high hopes for the lacquer thinner. My only question is whether or not the crystal itself will survive. I'm laughing outloud!!!! Quote Link to comment Share on other sites More sharing options...
eunomians Posted March 20, 2007 Report Share Posted March 20, 2007 Thanks for the excellent post. Great information. I would like to have some crystals done in the 2nd batch. And for the record, I think that not using Paypal is always a nice alternative Best regards, Euno Quote Link to comment Share on other sites More sharing options...
vaccum Posted March 20, 2007 Report Share Posted March 20, 2007 Great Info! Thanks for sharing!!! vaccum Quote Link to comment Share on other sites More sharing options...
notguilty Posted March 20, 2007 Report Share Posted March 20, 2007 hmmm $70 for a single crystal from outside the US seems a little steep to me.would the price drop if more people signed up? also what about cheaper international shipping options? i am cool with regular unregistered mail since its just a crystal.... and my watch apparently came with 'light AR coating' but i cant even see a hint of it.if i posted a pic would someone here be able to tell if there is any AR on it? Quote Link to comment Share on other sites More sharing options...
HauteHippie Posted March 20, 2007 Author Report Share Posted March 20, 2007 hmmm $70 for a single crystal from outside the US seems a little steep to me.would the price drop if more people signed up? also what about cheaper international shipping options? i am cool with regular unregistered mail since its just a crystal.... and my watch apparently came with 'light AR coating' but i cant even see a hint of it.if i posted a pic would someone here be able to tell if there is any AR on it? EMS is an option, not a requirement. If you can live with regular airmail, then it's $40. I'll change the wording of the original post. Quote Link to comment Share on other sites More sharing options...
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