Atom Adhesives AA-BOND FDA15

I got a 2.5 gram pack of Atom Adhesives AA-BOND FDA15 epoxy which cost me just under $10 including USPS shipping to try to coat some magnets similar to what @Benbeezy showed in his VIDEO.

I picked that particular epoxy because it is low viscosity and was developed for bonding and coating applications.  The epoxy is a thin liquid and I used a toothpick to "paint" the epoxy on the magnets.

I just finished my first try with this epoxy and I coated 4 parylene coated magnets and 3 regular nickel coated ones.  I am now waiting for them to cure which will take 24 hours at room temperature.  I expect the back sides to need another coat.

First, before I describe what I did, I can tell you that magnets suck to work with.  Get them a little too close to each other and they jump together.

I don't know yet if this idea is even going to work but I will describe what I did.  I used wax paper to lay the nickel magnets on to cure as @Cassox suggested in another thread and parchment paper for the parylene coated ones.

I wiped each magnet with rubbing alcohol to try to remove any oils and to clean them up.  I opened a corner of each side of the little pouch of epoxy and guessed at the ratio of epoxy to hardener.  The website for the epoxy states 100:20 / Resin:Hardener so I tried to add 5X as much resin.  This may not be the best way to do it but I didn't want to mix it all up at once especially since this is just a test.  There is not much epoxy in the 2.5 gram pack but it should do a lot of these tiny magnets if it doesn't harden up before they are coated on all sides.  I used an impulse sealer to reseal the pouch ends after I was done.  I only used a tiny amount so far.

I mixed the epoxy up on the parchment paper using a toothpick and placed the magnets on the wax and parchment paper for coating.  I used the same toothpick to pick up each magnet and dip it into the epoxy.  Then I placed the coated side down on the hopefully nonstick surfaces and painted the tops and sides.  The epoxy is thin so it coated them easily.

I'll update this thread when I see if the epoxy cures.  So far it looks like @ThomasEgi 's magnet levitation device would make this a lot easier (one at a time) and the magnets might be able to be coated and cured in one pass.


Comments

  • Are you planning on going over these with a second layer of epoxy as a "just in case" to fill in any gaps?
  • The first coat is done.  They will at least need the backs coated yet. 

    The parchment paper worked great.  The wax paper didn't work as good.  Part of the paper ripped off and stuck to the magnets.

    I'm going to let them cure another day before doing any more with them.  If they look good I might coat more of the ones I have left.

    The parylene coated ones are looking good.  The regular nickel coated ones didn't coat as well but they were the last ones done so I might just have not put enough epoxy on them.  I pulled one of the nickel ones off before they were fully cured and was able to scrape most of the epoxy back off it with my finger nail.

    The epoxy is softer than I expected so far but it might just need more time to cure since I guessed at the mixture and it wasn't real warm overnight where they were left to cure.

    There is some "flash" where they sat on the parchment and wax paper.  I'll decide if I should cut it off before or after the next coat once I see what they look like tomorrow.  I'm hoping the epoxy gets a lot harder but I haven't worked with this epoxy before so I don't know what it is supposed to do.

  • if your epoxy doesn't harden all the way up, you probably messed up the ratio. Epoxy can be very picky about this, even tiny errors (like a few percent) can result in big differences in the end result. Given you guessed the amount of epoxy this is most likely it. Speaking from years of bad epoxy mixing experience myself.
  • I checked the magnets this morning and they look like the epoxy did cure.  I just didn't wait long enough before.  It also flattened out and some spots didn't look coated good enough so they will need coated better.  They still need the backs done too.

    If I was going to do a lot of them I think the best option would be buy 2 small packs of the epoxy and mix it all at one time instead of guessing on the ratio.  If putting it in the freezer would keep it from curing for a day or two, only one pack would be needed or if they were heat cured that should work but I didn't want to risk weakening them from the heat.

    I took some pictures but haven't gotten them off my camera yet.

    I doubt I will try implanting any of these magnets especially with this first attempt at coating them but I do want to run them through some testing solutions when I'm done coating them.

    I have a fair amount of the epoxy left so I will try coating some more of both the parylene coated ones and the nickel coated ones next time I mix some up.  I'll try to do more after I'm done working today.  It looks like it will work but I need more practice coating them before I would trust them.

    My practice magnets will still be good for non-implant uses so I'm not worried about wasting them. 
  • edited August 15
    I didn't get a chance to do any more coating but here's a picture of my first attempt.  Took 3 tries to get the picture here.  Sorry but don't know how to remove the extra links.

    imageimageimage

    I also ordered 400 more nickel-copper-nickel coated N50 magnets since I think the ones I have now are weaker.  All same size 3x1mm.
  • I did a second coat on the first magnets and the remaining nickel plated ones I had here yesterday. I used more hardener on that batch and they cured much faster. This morning I coated all of them again. They are going to end up considerable larger than I hoped. More practice might help get a thinner but still complete coating. This batch will work for my intended testing and might be safe for implanting but the size combined with the fact that I think they were not the strongest magnets to begin with would make them less desirable.

    I might have enough epoxy to do a few more magnets. I still have some parylene coated ones that I haven't coated with epoxy yet but want to see how this batch does before wasting them.

    I'll take more pictures when this batch cures.

    I'd like to figure out the magnetic levitating device. That would probably eliminate most of the flash and allow a thinner coat to be put on the magnets. The epoxy is thin enough to "paint" on the magnets. The main problem is getting both sides coated without leaving a lot of "flash" where they sit on the parchment paper.

  • Still waiting for last coat to cure but doing so many coats has made the magnets way too big for implanting in my opinion. I didn't see a way to embed an image or a way to do anything but add plain text with this new Vanilla forum. Could just be my old computer.

    https://c1.staticflickr.com/5/4372/36489364451_24c4803267_o_d.jpg

    It's a little hard to see in that photo (top right) but I got some bubbles in the epoxy which might not hurt anything but it can't be good.

    I still think with more practice and perhaps a different technique for coating this epoxy, it could work better. I dipped the magnets and then put more on top after they were on the parchment paper which really made a thick coating.

  • I just had a random thought: http://www.supiri.com/cultures/food-drinks/how-they-make-smarties/

    How often do you see a flawed smarty? In a box of how many? Maybe adapting the process for magnets could work?

  • edited August 18

    I just checked my last attempt at coating the magnets and they are still sticky which means that guessing at the epoxy to hardener ratio was a bad idea.

    I removed one from the parchment paper and have it soaking in saltwater right now even though it isn't cured good enough. None of these will be implanted anyway so I had nothing to lose.

    The one I am testing is not as much over sized as I thought. Bigger than what I started with but probably not too large to implant if they had cured right. I'm going to give the remaining magnets more time to possibly cure better but right now I can't tell if cutting or polishing them could remove the excess epoxy.

    They still have some flash which would make coating them with TiN or Titanium (if that is even possible) undesirable but "shouldn't" be needed assuming the medical grade epoxy is safe. I expect they would be similar to the silicon coated ones that are about the only commercial ones available at the moment.

    Like I said above, I ordered 400 more N50 Nickel-Copper-Nickel magnets off ebay but they will likely take at least a month to arrive here. They were real cheap (less than a penny each) and I have other non-implant uses for them. I may order a couple more packs of the epoxy sometime and try the coating again using the correct ratio of epoxy to hardener.

    I still feel this method would/could work. I don't have any intention of manufacturing these for others (not confident in my ability yet) but the epoxy is not real expensive if anyone wanted to try this method on their own. The smallest 2.5 gram pack is plenty to coat magnets with but you would probably want to buy 2 of those packs so the whole thing could be mixed at once to assure the correct mixture.

  • edited August 18

    Playing around with the still not cured magnet gave me an idea.

    If you were to catch the epoxy after it sets up but before it is fully cured, it might be possible to mold the putty like epoxy around the magnet eliminating the flash problem and possibly getting a full coat in one pass.

    I was able to form the soft, uncured epoxy into a nicer and more compact shell around the magnet. I have a small amount of epoxy left here but only have a few parylene coated magnets left to experiment with.

    EDIT : Now that I think about it some more, maybe picking a thicker version of the epoxy to begin with is the better answer.

  • I finally got half of the magnets (200 pcs) I ordered off ebay so I used the last little bit of epoxy I had left. I still got the mixture wrong and that batch didn't harden either.

    I still think it would be possible to coat your own magnets but guessing at the ratio of resin to hardener was a bad idea. There is type AA-BOND FDA8 epoxy that is still low viscosity but has a 100:100 mix ratio that MIGHT be easier to guess right. Best bet would be to order 2 small packs of epoxy and mix it right.

    I think I would be better off getting either the medium or high viscosity epoxy if I try again. I couldn't get the magnets fully coated in one pass with the low viscosity epoxy. I have some ideas but no more epoxy to test them.

    I notice the lowest cost shipping has almost doubled in cost in less than a month since my last order so a single pack costs more for shipping than for the epoxy.

    It looks like there are or will be implantable magnets available again from Cassox so I might not waste any more time and money experimenting with this idea.

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