scratch resistant coating for glass or plastic? - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: May 10, 2019, 12:00:09 am
content: If you want to put a scratch resistant coating on a plastic or glass object (like the option offered by eyeglasses and face shield manufacturers) what is a good place to start?

author: KL27x
author_rank: Super Contributor
timestamp: May 10, 2019, 01:10:07 am
content: Cell phone super snake oil liquid armor treatment? Maybe you can test it and post some data.Glass has a moh of 7. That is pretty scratch resistant, already. I imagine the liquid treatments have some kind of elasticity or self-healing to prevent small scratches from aluminum oxide dust/debris, rather than having some harder minerals in there that form a protective layer yet somehow ends up transparent and smooth.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: May 10, 2019, 01:18:50 am
content: Depends on your needs. You can put a sapphire coating on glass, and some vendors claim to be able to do it on some plastics. Very scratch resistant. Fairly hard on the wallet and not at all practical for onesy twosy kind of projects. There is a lot of experimentation on set up time.This opening leads to the fact that all of the good hard coatings I am aware of are CVD (chemical vapor deposition) processes. Not the kind of thing you can order on line and paint on. Unless you are a very well healed and advanced experimenter it just isn't going to happen in the hobby world.

author: coppercone2
author_rank: Super Contributor
timestamp: May 10, 2019, 01:35:09 am
content: there are claims at 'fluid film' coating and spray coating, the fluid film being one wehre you dip the object into a bath at a certain angle and withdraw it.https://materion.com/-/media/files/advanced-materials-group/ac/coatingmaterialsnews/cmn19_2.pdfMy main reason for asking was because of grinder face shields and safety goggles, I actually restore these with abrasives to decent condition at the expense of my time (I just don't like throwing these objects away). But if you want a 3m scratch resistant anti reflective one, the replacement part goes up from 8$ to 20$ I was wondering if there is some kind of miracle product that does not use advanced technology that would make it more ware resistant.I thought about using ceramic coatings that you use on cars but I don't know how that would look on a optical surface.If you are interested it takes about 1ish hours and 2$ of abrasive materials or so to restore a rather damaged face shield (i.e. grinding something at a weird angle with a bunch of sparks hitting you in the face like a dumbass). If you do the repair in 1 sitting you will begin to question your actions due to labor. If you use less sand paper you can probably do it for a dollar.It makes sense to me because I tend to group things up in my head with budgets and expenditures, i.e. safety equipment costs go into one category, abrasive materials into another category, cutting things into another..

author: Rerouter
author_rank: Super Contributor
timestamp: May 10, 2019, 01:47:18 am
content: For restoring what you have. You can do like we do with automotive curved lenses get a dremel with a set of polishing wheels. And use brasso metal polish to clean the surface. The rotation speed can easily cause the scratch corners to melt over meaning you rarely need to ablate the full scratch depth.Even just with a rag for 3-4 minutes would likely have all but the deeper scratches optically clear

author: helius
author_rank: Super Contributor
timestamp: May 10, 2019, 02:01:19 am
content: Apparently there are two-part coatings (epoxy?) that are sold as scratch resistant:https://www.neicorporation.com/products/coatings/abrasion-resistant-coatings/

author: coppercone2
author_rank: Super Contributor
timestamp: May 10, 2019, 03:47:56 am
content: Quote from: Rerouter on May 10, 2019, 01:47:18 amdamn I just did it sequentially :-/i would never think to use brasso on plastic lol

author: KL27x
author_rank: Super Contributor
timestamp: May 10, 2019, 04:39:09 am
content: I restored my first face shield after setting a grinder down on it before it stopped turning, ending up right over an eye. I dunno, I just use fine sandpaper then w/e polish I had at the time on a buffing wheel. Then hand buffing with... I think I used toothpaste. Probably spent half an hour. Not great, but usable.But the same day I ordered 4 more. I installed the new one when it arrived. I rather buy face shields for a few bucks a pop than to not use protection because it's annoying. But I admit I didn't throw the old one out, though. I suppose one day that might be the best I have on hand.A brand new face shield is dangerous in a way though, too. I have accidentally left the shield up while thinking it was down. It's hard to tell the difference... other than your face slowly creating its own sauna under there, which is why I would have flipped it up, I think.

author: SparkyFX
author_rank: Frequent Contributor
timestamp: May 10, 2019, 06:06:05 am
content: Are throwaway films (as for motorcycle helmet visors) an option?

author: Rerouter
author_rank: Super Contributor
timestamp: May 10, 2019, 07:50:43 am
content: Yeah brasso is the WD40 of cleaning scratches at our work, even been used to erase a 1mm deep, 15cm long scratch in textured dash paneling once :p, Truck instrument clusters, and marine small gauges get scratched up to crap, Its nice when you can give them back there device in such a good state that they start weighing up bringing in the rest to just clean up for them.

author: KL27x
author_rank: Super Contributor
timestamp: May 10, 2019, 05:13:18 pm
content: I probably used Brasso on my shield +- chromeox compound. My bottle of car polish has been used up for several years.Ironically, brass cartridge cases are one thing that I've heard you should not use Brasso on. The ammonia apparently weakens the brass and leads to splits.I bet Mothers would work fine, too. Most car and metal polishes contain the same basic abrasive, called microcrystalline quartz, which sounds fancier than what it really is. Diatomaceous earth. The millions of years old shells of dead diatoms, free for the taking in certain places on earth that used to be an ocean floor, for cents to the pound.

author: coppercone2
author_rank: Super Contributor
timestamp: May 10, 2019, 10:09:00 pm
content: I actually used maquires compound, scratch x 2.0 and then maquires polish lol, after all the sanding steps.I actually noticed a improvement in every step, particularly when I jumped down to the polish after the scratchx 2.0.The improvement between the scratch-x and compound was slight. It was usable at that point, for imprecise work, but the polish (rated 3 on the abrasives scale for car work that is in another thread of mine).I did not do each step for long though. 2 full sets of overlapping passes per compound or paper. I also washed it between every step with soap and a soft brush in the sink.

author: coppercone2
author_rank: Super Contributor
timestamp: May 10, 2019, 10:15:55 pm
content: Quote from: SparkyFX on May 10, 2019, 06:06:05 amexample / cost?The main enemy I want to fight is dust from abrasive cutting methods, particularly angle grinder related.

author: KL27x
author_rank: Super Contributor
timestamp: May 11, 2019, 03:21:45 am
content: Ghetto condom = saran wrap! Apply like window tint, with a spray bottle of soapy water and a squeegee. Just let it stick by surface tension. It'll take only half an hour to take off the shield, apply the saran wrap, trim and reinstall. 10 seconds of grinding, rinse and repeat. You'll save a hundred dollars a year.... on grinding supplies you didn't use!Or when sparks are coming at your face, move your head out of the way... reposition the guard or the grinder... move the workpiece. Seriously, though, I don't think it's a good idea to shoot sparks at your face. Not necessarily that worried a chunk of stone/disc will shoot at just the right spot with enough force to break the shield and maim you... but just that it's a bad habit. One day you're gonna install a brand new shield and forget it's up.Bonus: build a grinder that spins in reverse, for those spots where you need it. Left handed spindle and lock nut.Or buy cheaper face shields. They're under 5.00 each on Amazon for single quantities. Polycarbonate. I bet you can get them for half that in bulk, if you shop around.Doh! You can buy an entire flip up face shield from HF for 4.00. They also have a mesh shield. Maybe you could put a mesh shield in front of the polycarb shield for the ultimate protection.

author: coppercone2
author_rank: Super Contributor
timestamp: May 11, 2019, 03:43:16 am
content: i actually boil my flap wheels in solutions to clean em out to save money lol

author: KL27x
author_rank: Super Contributor
timestamp: May 11, 2019, 08:55:16 am
content: ^That sounds odd.My flap wheels get used up and disappear from the edge in. They're done when the flaps are even with the backing disc. There's nothing left to clean unless you want to rub the edge of the backing disc against your workpiece at 11K rpm. What, did you find 2000 grit flap discs or something?I have ground the backing disc with a second grinder by say 1/4" to 1/3" to get more use out of them. It worked, but the smell is so bad, I don't think it's worth it to save 10-20 cents. The flappers I am using are barely more than a dollar a piece.*edit: doh, you probably meant a flap wheel that goes in a drill or whatnot? I have never used one of those. But maybe you should use the solvent on the workpiece before you gunk up your flap wheels on it in the first place?

author: coppercone2
author_rank: Super Contributor
timestamp: May 11, 2019, 03:58:09 pm
content: they get clogged with shiney shit if you grind mill scale off or really crusty old stuff that's been outside a long timei don't know what it is exactly but if you boil it in water with some alcohol and soap etc it cleans up and seems to remove metal faster. I use Walter brand grinding disks on a angle grinder, the other stuff is not worth it but the walter ones are like 10$ a diskYou get this effect that kind of looks like grease being dragged along the edge of the sanding disk when its clogged uphttps://www.walter.com/en_US/products/abrasives/blendinghttps://www.walter.com/en_US/products/abrasives/blending/enduro-flex(the one I use the most)I want to try this but I felt like I was being menaced by the price taghttps://www.walter.com/en_US/products/abrasives/blending/enduro-flex-2-in-1

author: mzzj
author_rank: Super Contributor
timestamp: May 11, 2019, 05:05:52 pm
content: Depending on plastic even a PET film can be a big improvement, ie something like thishttps://www.ebay.com/itm/HD-Clear-Screen-Protector-Cover-Guard-Shield-Film-for-iPad-Pro-12-9-Tablet/182665441981?hash=item2a87b572bd:g:qxIAAOSwXWhb8Yjqcut to size or order smaller ones intented for smartphones.I have plastic protective film on my DSLR screens and while its not totally scratchproof its like 10 times better than the bare sony DSLR screen. And replacement is like under a 1 euro/usd

author: coppercone2
author_rank: Super Contributor
timestamp: May 11, 2019, 06:17:16 pm
content: I think I will actually buy that and buy another helmet so I can use different ones for different grits, like I think if you are blowing off weld material from some ratty nasty steel with 36 grit or a grinder disk, you should use a different protector then when you are using a 60 and 120grit sanding disk and so on.i am thinking 3 for grinder/36/40/brushes (they can grab and throw something hard), 60-80, 120I am thinking 3. The one for the nasty work I might try to get the armor on.Will that phone thing work on a grinder shield though? those grinder shields are pretty flexible.I need more angle grinders lol

author: KL27x
author_rank: Super Contributor
timestamp: May 11, 2019, 06:59:45 pm
content: Gotta find a much better price before even wanting to try that.Are you sure you are using polycarbonate shields? They also make them in other materials that are not as heat and abrasion resistant (let alone impact).QuoteGrainger sells PETG shields for 2 bucks a pop. Probably strong enough to satisfy your need to stare into the muzzle end of your grinder with flap discs, at least. Polycarbonate is supposedly better for abrasion and sparks, but maybe the price difference will be worth it if you're trashing shields at a rate worth worrying about.If your flapwheel gets gunked up with mill scale(??) try pressing the wheel against a piece of scrap a bit harder. It should clean/wear right out. Or maybe these expensive flap discs are optimized for something else, other than grinding steel like the cheap ones do perfectly. If you spend 5-10x more for the "good stuff" it is supposed to save you time, at least, if not money. Mill scale or rust has never bothered me. Nor paint. Worst was some siliconish sort of sealant, and even that just worked itself out after grinding some steel.

author: coppercone2
author_rank: Super Contributor
timestamp: May 11, 2019, 07:34:40 pm
content: I don't know, if I boil them once in a while they seem to do a better 'bright' finish on shit, it feels like sometimes I am dragging a grease film around with the grinder. It feels like when they are clean, when you traverse with the grinder the clean bright 'wake' of polished metal left behind the grinder is wider with the same pass conducted, so you can shift in the perpendicular axis of travel by a greater degree for a wider cleaning pass. It's more apparent on 80 and especially 120 grit, the 40/60 grit flap wheels are more resiliant and they do clean as you describe if you hit a hard edge with them. I had the same wheel set around since 2015 (granted they are not used too much), enduroflex and enduroflex for aluminum/stainless, 40-60-80-120, the performance of all of them went up when they were cleaned after a year or so.The manufacturers call this 'glazing' and 'loading' in the brochures.https://www.walter.com/documents/10195/31852/Blending_Selector_Guide_En.pdf/4b8869b1-400a-4f07-8f67-7b17544706cfIf I had all those series it would probably work better depending on what I am working on, I think I am using the wrong tool for the job.Probably should add a flexcut-milscale for first passI often restore stuff that was like, made with millscale and shady welds in the factory, got rusty/greasy, kinda poorly repainted, left outside to accumulate more rust,grease for 10 years.. also had impossible geometry.Maybe people that work with actual construction/engineering grade materials more don't notice these problemsI use a knotted wire brush on it first to get as much crap off as possible, but its often extremely bad.

author: KL27x
author_rank: Super Contributor
timestamp: May 11, 2019, 07:56:35 pm
content: QuoteAccording to the brochure you linked,"simply trim down the ECO-TRIM backing and your discs top performance is restored," which goes back to just wear the flaps down and new abrasive is exposed.I think it's moronic they sell these trimmable discs for 2-3x as much, when you get like 30% more grinding out of them, tops.QuoteDo you watch any of those tool restoration You Tube channels? Take old rusty tool apart, remove the rust, shine it up, put it back together?Mill scale is great. It's more abrasion resistant than the steel underneath. It's more corrosion resistant than the steel underneath. I try to not remove it, unless I'm gonna paint or for shape/dimensional reasons. I won't remove it for esthestic/shininess reasons. I operate from the assumption that steel is gonna rust/discolor, and bright and shiny steel is gonna look the worst when those spots happen.

author: coppercone2
author_rank: Super Contributor
timestamp: May 11, 2019, 09:37:18 pm
content: I thought it was like a ceramic sponge, which will keep oil absorbed, so paint will not adhere to it good, and temperature changes will cause oil pressure from the ceramic into the paint to make it flake eventually? so it makes degreasing hard tooand I like to paint all surfaces that are not going to be fittings or slides etc

author: coppercone2
author_rank: Super Contributor
timestamp: May 11, 2019, 09:41:48 pm
content: I thought for trimming they meant to make the perimeter sand so you can so inside corners. Like if you wear out the overhang that can hit something perpendicularthe nice option of course is to avoid fucking angle iron and use square stock when possibleI want to see someone like 'the grinding doctor' on youtube investigate flap wheels and stuff under electron microscope etc to determine where the cost performance optimization is for sane use. sand paper tooFor instance I am actually really happy with the 'sand net' that diablo made for wood working, you can actually get decent life out of 400 grit paper sanding wood with it. Buying it was like swallowing glass at a horse race though. I almost turned around half way home to return it because I kept thinking about the price difference.https://www.diablotools.com/products/DND050080H10II wonder if they can make it into higher grits.

author: KL27x
author_rank: Super Contributor
timestamp: May 11, 2019, 10:51:22 pm
content: Quotehttps://youtu.be/uxVGsaHr-mc?t=64My take:You are almost always sanding at a bit of an angle with a flap disc. It will disappear from the edge to center. You don't trim the backing to get into inside corners, you cut it so you can use more of the sandpaper. The disc starts out with the flaps extending a bit beyond the backing to begin with, then it wears down. Then the backing disc starts to contact the work surface, and instead of refreshing, the sandpaper becomes dull.But if you trim the backing disc too far, you will end up in the gluey center where the paper will stop disintegrating/refreshing because of the amount of hard glue in there between the flaps, anyway. And/or the flaps will start to fly off at 100 mph. So unless you have a lot of weird jobs where you use the grinder totally flat, or maybe you wanna shape the ends of small bits of metal, you can't use up the last half of the sandpaper in the center. You just throw that part of the donut away.Exactly the same way you use grinding wheel.If you put the grinder flat on a surface, it will move around and be difficult to control and leave a stupid scratch pattern, anyhow. And you would have to remove the guard. And the disc will probably clog. Goes back to my point about surface area. I won't go so far as to say that's "doing it wrong," but try tilting your grinder 15-25 degrees and using just the far end and stroking that like the tip of a paint brush in the up/down or forwards/back direction, rather than trying to use a grinder like an orbital buffer. Smaller area of action, but faster results without clogging/glazing/burnishing/heating.Forgive my preaching. There is an entire generation of people raised in the internet age that thinks you need a flat abrasive surface and to hold it flat against an object or else you will instantly ruin it. One day people will think you need a 5 axis mill and a 3D printer to make a table. Even one of my inspirations, Matthias Wandel, in his "quest for straight planar blades," how do you think he achieves this? By dragging out a 200 lb giant slab of stone and a dial indicator. Duh, just sharpen the damn blade, lay it down next to a straight edge, then take down any obvious 1 thousandth or greater high spots, easily visible by naked eye. If you get any spots that big, you might also want to learn how to sharpen blades.

author: coppercone2
author_rank: Super Contributor
timestamp: May 12, 2019, 12:28:35 am
content: arent you supposed to use a plane to make flat tables?that sounds like verification for a machine axisAnd I think you are supposed to use a sanding disk not a flap wheel if you want to go perpendicular, I find those pretty useless because they get destroyed very quickly, I usually almost buy them then put them back lol. They seem like hack add ons to the angle grinder. My milwakee polisher takes the little 3 inch sanding pads but they get worn out so ridiculously quick its hard to justify a use for them?? I feel like I am burning money. They last like 1/100 th of the time a flap wheel does, it seems like a tool for automotive plastic etc.Ill use that then I finally make one of those stainless steel polished hand rails they are always working on in the advertisementsIt's kind of hard to beat the gap filling paint primer instead of going to crazy grits on steel.Then I need to ask myself why I am obsessed with aluminum finishing since they sell etching primer for it :-/Mainly I want to make aluminum skeletons for equipment chassis that are light and strong (like a interior roll cage). I don't like the body work being the structural strength for test equipment. Structural sheet metal use needs to get lost, I fucking hate all the strength related bends, screw use minimizations (which use interlocking finger bends), rfi gasket eliminations, vent holes being part of the fucking structure (rather then screw in vent panels you can actually clean) etc.then getting it back together requires like a expert panel beater if it gets damaged or old (jesus chirst dehumidifiers and window air conditions are one of the worst things I have ever worked on). Seriously fuck window air conditioners. Holy shit.You can easily land in a situation with a big window AC frame where you need like 3 people and a rubber mallet to get it back into its enclosure (and it rests on a piece of bare styrofoam, that they actually use, as a real sub assembly, despite weighing like 60lb). When I used to own one I had to take it apart to get the grime out of it every spring when I would install it and I swear it just made me psychotic every time.a metal box now is like a fucking wicker basket. feature creep like crazy. now their even putting traces into the chassis with conductive deposition. It just too much for me.I mean its KINDA cool because its like a big ASIC in regards to systems engineering but usually unless its impressively small or cheap you just look at it and go like wtf is this shitI can imagine the window AC of the future, unless its really cheap, is going to make people increasingly more homocidal. They will find a way to put a freon line into a crimped sheet metal in the chassis rather then to run a copper tube, with a single turn sheet metal thread hydraulic fitting. Not just for rocket systems anymore!!

author: KL27x
author_rank: Super Contributor
timestamp: May 12, 2019, 01:03:01 am
content: QuoteWell, yeah, a sanding disc will make flat surfaces... but not a flat surface larger than the disc. If you wanted to bevel the end of a round with a sharp facet or to true the end of a piece of angle or tubing, then the sanding disc would be perfect. If I wanted to flatten, say a welding table, I would use a flap disc the way I described. And a straight edge. Maybe a grinding wheel, at first, if there are really big high spots.Even when you use a plane to flatten a table top, you don't just start at one end and work over to the other, and magically end up with a flat surface. You have to aim it. You have to identify the high spots and work them down. Then examine, again. It's a reiterative process.* The plane helps you to take these high spots down quickly without accidentally digging too deep and creating a new super low spot. Of course we have a whole generation of people that will rather build a giant router sled to flatten a bench, because they apparently can't trust they own eyes and hands using straight edges and winding sticks to even tell when a bench is flat enough. (If they can't tell the ffing difference, then how is it not flat enough, already?)If you already know this, and you say this:Quote... that begs the questionHave you ever worn out a flap disc? How/when do you throw them away, or are you still boiling and using them forever?*Using a jointer plane to true the edge of a board is one of the more "automatic" hand planing processes. Notice whenever you can use a machine to "automatically" true/flatten the stock, the machine has to be bigger/wider than the stock. A jointer plane works just on the edge of a board, and yet it is the longest and heaviest hand plane, to make it work somewhat automatically.There seems to also be a lot of confusion over how to use even abrasive stones. There are two kinds. Hard (dense and slower wearing stones, not moh of the abrasive) and soft (usually man-made, fast wearing) stones. The hard stones are files, and the soft stones are laps. You have to flatten the soft stones, regularly. Harder stones don't actually need to be flat to sharpen blades. Rather than letting the stone dish, you can favor the edges of the stone moreso than the center and let the surface of the stone get convexed over time.** Then it works even better. You use the stone like you would draw file, drawing the edge over it, abrading a small section at a time, rather than as a lapping surface covered in lapping compound. This is the same whether a knife, a chisel, a plane blade, or a straight razor. I get a chuckle out of watching people on Youtube flatten their Arkansas stones. Every single one of them gives up before they are done, and then they have a stone that is slick and doesn't work unless you scratch it up with a diamond plate every other week. The only reason these stones are flat to begin with is that this is how saws cut, and consumers don't know any better and think all stones should work the same way. These folks probably think in medieval times you needed a giant flat stone to sharpen a sword. Unless you added some lapping compound, a "hard" stone would have to be like 12 grit to function like this. This why we don't make files that are 1 foot wide.**If you have a hard-wearing stone that is already dished in the middle by an idiot (including yourself), you can simply ignore the center and just use the rest of the stone. Knock down the corners/edges as needed. These hard-wearing stones should never be dished except on purpose for sharpening small, pointy tools.

author: coppercone2
author_rank: Super Contributor
timestamp: May 12, 2019, 01:18:57 am
content: what does glaze cleaning have to do with trimming the thing? I don't use them when heavily glazed.I bought the expensive ones because I was under the impression the abrasives were better, some how I missed the fact you can shorten them on purpose. Like the zirconium was of higher quality some how and maybe the glue was better or something. I never thought about it too much. They shorten naturally a bit if you are doing the interior of a angle iron and hit the end so the back face acts like a cutting edge on the disk when most of the material at the tip is gone. The ones I use more are a bit less wide then the less used ones.

author: coppercone2
author_rank: Super Contributor
timestamp: May 12, 2019, 01:32:54 am
content: they actually wear alot from natural use, I never noticed until now. Never on purpose resized it.

author: KL27x
author_rank: Super Contributor
timestamp: May 12, 2019, 02:20:18 am
content: ^Exactly. When you're down to the backing disc, the sandpaper stops wearing/refreshing. Then it gets dull. Those are done, other than for odd jobs where you can use the center.QuoteMaybe they are excellent. Maybe they cut a lot faster and last a lot longer for certain things. Maybe they make things shinier. I dunno. I paid a buck a disc for my last box and they last a really long time.

author: coppercone2
author_rank: Super Contributor
timestamp: May 12, 2019, 03:11:03 am
content: I am scared to get the cheap shit until I have experience with the expensive stuff so I know the difference. I feel like a bad product can really screw you over if you go cheap with no experience. just pray its not a gouging conspiracy.with tools its clear night and day. with disposable abrasives I am still not sure because they are used in a skillful way thats situation dependent making metrics hard. With cutting tools it seems fairly obvious with the tests that are performed for demos.

author: coppercone2
author_rank: Super Contributor
timestamp: May 12, 2019, 03:28:37 am
content: I do feel your rant in regards to complicated tools with regards to 3d printing. Especially when its used to create low strength boxes with poor electromagnetic specs.As for multiaxis machines I am not sure what I would use one for. It seems useful for hydraulic devices like impellers and propellers etc.I will say there is no better way to discourage me from watching a youtube channel then to put a CNC - something on it.With most of what I do mechanically, accuracy and repeatability is not required to any extent so long I can live with stuff looking a bit funny (which I do). If the fitting is shoddy and it lowers strength I can just make it a bit heavier to compensate?If you youtube 5 axis CNC its either engine blocks, propeller/turbine structures or art.