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  1. RPF Premium Member cavx's Avatar
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    Dec 24, 2017, 5:38 AM - Epoxy and Different Ways To Use It. #1

    I am posting this here as I figured it might be better here than in the prop section I normally hang out in.

    Anyway long story short, I have been experimenting with epoxy and different ways to make stuff using it that is not the usual casting from a mold.

    So what I have discovered over the past few weeks is that this epoxy is quite a versatile product. Most people just cast with the stuff and most don't like it as it can get really hot and can shorten the life of a silicone mold.

    That aside, here is my share.

    1. Casting flat sheets up to 4mm thick and you have a short window of time where you can then cold form these into a jig and this will actually hold it's shape until it hardens up. If you bake to post cure, then it gets baked into that new shape. A cast/formed part is about 0.6 of the weight of the same part made from Perspex. I can't help but think about hard amour here.

    2. A great alternative to polyester resin for fibre glass. Not only do get an extended work time, you don't get the nasty fumes and this works a treat with both chopped strand mat and woven cloth.

    3. Today I mixed it with sand. Weight is not an issue with what I want to do here, but the volume is so I wanted a filler so I can get more out of the resin kit. It seems that I can mix this at about 20:1 sand to resin and it came out like a dry concrete mix that seems to cling to vertical surfaces without slumping. I was able to press it into a silicone mold and it took the shape well. And because it is clear it could be pigmented as well as I actually want my parts black.

    When I made my Fifth Element stones, I added texture, but how cool would packed sand look? I don't see why a surface can't be coated in epoxy and the sand applied and then let the epoxy cure. The sand would be glued to the surface and retain the natural look with out the wet look epoxy gives it.

    Image 1 sand mix in a silicone mold
    Image 2 demolded sand mix
    Image 3 fibre glass over EVA Foam
    Image 4 both cast and cold formed parts
    Image 5 epoxy over foam as a sealer



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  2. xenobiologist RPF Premium Member Leigh's Avatar
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    Dec 24, 2017, 10:16 AM - Re: Epoxy and Different Ways To Use It. #2

    I've been using polyester due to familiarity... I've got to try this stuff!

    Thanks for sharing
  3. RPF Premium Member Mr Mold Maker's Avatar
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    Dec 24, 2017, 1:15 PM - Re: Epoxy and Different Ways To Use It. #3

    While epoxy has less noticible fumes it is still very toxic. Use in a well ventilated area with a proper respirator. Myself, and many other folks I know that have used epoxy for a while? A sensitivity can be developed.

    A tip, cut your glass cloth on the bias of you want it to conform to curves more easily.

    If at some point, weight does become an issue for you, a trick I learned from Ironhead is to add microballoons to your epoxy facecoat, and back with model airplane fiberglass. It will make a strong, but feather lite part. Great for helmets or long parts. You can also squish mold (lay up two or more halves of a mold, and then put a "butter" layer of epoxy on the seam, and squish it together) to make epoxy parts in molds you wouldn't be able to get a hand or brush in.
  4. RPF Premium Member cavx's Avatar
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    Dec 24, 2017, 7:56 PM - Re: Epoxy and Different Ways To Use It. #4

    Mr Mold Maker said: View Post
    While epoxy has less noticible fumes it is still very toxic. Use in a well ventilated area with a proper respirator. Myself, and many other folks I know that have used epoxy for a while? A sensitivity can be developed.

    A tip, cut your glass cloth on the bias of you want it to conform to curves more easily.

    If at some point, weight does become an issue for you, a trick I learned from Ironhead is to add microballoons to your epoxy facecoat, and back with model airplane fiberglass. It will make a strong, but feather lite part. Great for helmets or long parts. You can also squish mold (lay up two or more halves of a mold, and then put a "butter" layer of epoxy on the seam, and squish it together) to make epoxy parts in molds you wouldn't be able to get a hand or brush in.
    Thanks guys for responding. I used to only use polyurethane and decided to test epoxy because of the price being good. And wow what great results.

    Yes I am always in a well ventilated area and I always use gloves.

    Merry Christmas guys.

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  5. RPF Premium Member cavx's Avatar
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    Dec 27, 2017, 8:48 PM - Re: Epoxy and Different Ways To Use It. #5

    Round 2 with the sand mix and I think I this batch will fail due to not enough resin. If it results in a throw away, it was the last bit in the bottle, so not enough for any main project anyway.

    I measured the amount of sand by filling the silicone mold, then dumping that into a bucket. The amount of sand to resin should have been about 10:1, but it was really dry today, so will be interesting to see what I get when I demold.

    The little test biscuit was a winner. Hard, and it just bounced when I dropped on the concrete from a 1m off the floor. The difference there was I also added the sand to the resin, not the other way around as I did today.

    What I did like and might come in handy for weathering of my BB-8 is the residue left in the last mix tub.
  6. RPF Premium Member cavx's Avatar
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    Dec 28, 2017, 1:02 AM - Re: Epoxy and Different Ways To Use It. #6

    Considering I ran out of resin, I am not unhappy with the result. Edge detail is good.

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  7. ZeroSum's Avatar
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    Dec 28, 2017, 9:04 PM - Re: Epoxy and Different Ways To Use It. #7

    Pretty cool. How strong is it? What does it take to break it? If you were to drop that casting on the concrete path, will it crack? Also, does it have a sandy texture on the outside or is it more of a resin feel?
    Cheers
  8. RPF Premium Member cavx's Avatar
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    Dec 29, 2017, 4:06 PM - Re: Epoxy and Different Ways To Use It. #8

    ZeroSum said: View Post
    Pretty cool. How strong is it? What does it take to break it? If you were to drop that casting on the concrete path, will it crack? Also, does it have a sandy texture on the outside or is it more of a resin feel?
    Cheers
    Not sure about the big part as I didn't have that much resin in the mix, but initial test piece is as solid as a rock. It just bounced off the concrete. I might do a stress test on the bigger part today now that it has had time to post cure.
  9. RPF Premium Member cavx's Avatar
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    Dec 30, 2017, 5:08 AM - Re: Epoxy and Different Ways To Use It. #9

    ZeroSum said: View Post
    Pretty cool. How strong is it? What does it take to break it? If you were to drop that casting on the concrete path, will it crack? Also, does it have a sandy texture on the outside or is it more of a resin feel?
    Cheers
    OK. This part was hard but it did crack once subjected to stress. It seemed to handle impact OK.

    As for the surface, it would depend on the mold. Mine is smooth inside so I got a smooth surface on the front. However the back has a sandy texture.

    Definitely needed to add more resin to the mix. As I mentioned, I ran out so the mix was a bit too dry.


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  10. ZeroSum's Avatar
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    Dec 30, 2017, 5:17 AM - Re: Epoxy and Different Ways To Use It. #10

    Interesting stuff! I always like hearing about things like this
  11. RPF Premium Member cavx's Avatar
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    Dec 30, 2017, 5:21 PM - Re: Epoxy and Different Ways To Use It. #11

    ZeroSum said: View Post
    Interesting stuff! I always like hearing about things like this
    I started testing this as I was curious about how it would set up. I was going to make a sand stand for a 1/2 scale BB-8.

    There is 2 sides to this, either you mix it dry where it will bond, but not be really strong, or mix it wet and let the epoxy do what it does best. For a dio where you want the wet look or even water, this works. For a dry look like BB-8's stand, I'd be best coating the surface in a wet mix, then sprinkle dry sand on that and let the epoxy glue it down. The dry excess would fall away after curing.

    For the alien tile, these are actually going to be sound diffusers for my home cinema that give the walls a future or sci-fi look. They need to be dense, but due to the volume, I don't want to be spending $1000s of dollars to make the 20 or so tiles. I wanted a dense filler, so I decided to test sand as that can be bought very cheap in bags. It is now just a case of getting the mix ratio right.

    The fiberglass tests I have done are amazing. Epoxy is both light and strong, so when reinforced with fibre glass, is really tough. There was a guy that actually made body armour from this and it stopped all types 12 gauge shot gun rounds except the "solid" rounds.

    I will buy more of this in the coming days and continue my R&D.
  12. joberg's Avatar
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    Jan 3, 2018, 8:15 AM - Re: Epoxy and Different Ways To Use It. #12

    TFS those tricks and experiments you did with Epoxy...
  13. RPF Premium Member cavx's Avatar
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    Jan 3, 2018, 4:51 PM - Re: Epoxy and Different Ways To Use It. #13

    joberg said: View Post
    TFS those tricks and experiments you did with Epoxy...
    You're welcome. Hope others can do some cool things with this stuff.
  14. RPF Premium Member cavx's Avatar
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    Jan 14, 2018, 5:42 AM - Re: Epoxy and Different Ways To Use It. #14

    So I have been thinking about how to make female tools for my Vacform using this stuff and I read that it does not eat closed cell foam. So the idea is to carve the foam into a male master part, coat with epoxy and maybe even some fibre glass, and then dissolve the foam using acetone. What I should be left with is a perfect (hollow) female version of the master part. Given the sand idea works, the bulk of the tool could be made using that to avoid excess resin.

    Obviously, the tools will need to be planned to avoid any undercuts on complex parts.

    Anyone see a reason why this won't work?
  15. RPF Premium Member cavx's Avatar
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    Jan 20, 2018, 5:04 PM - Re: Epoxy and Different Ways To Use It. #15

    So I got more epoxy and sand.
    It came out quite good. It is heavy but strong.
    I used the initial test part but should have placed a thin layer in the mold first.

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