Resin Encapsulation

Sharpie

Well-Known Member
I too have memories of Plasticraft from the 1970's. I have a couple of items I made for relatives who have long passed away and I was given them back as momentoes. They are still clear which is quite a surprise.

You're right, the resin was really smelly.
It started with a Christmas present, the Plasticraft kit with the ceramic multi-cavity mould, which was easy to use. But I soon got frustrated with making tiny things, and so moved up to bigger, i.e. paperweight sized stuff using glass tumblers as moulds, which used a whole bottle of the resin, which is when I ran into the problems of trying to cast larger pieces, and some disappointment, but figured out a way around that eventually myself. No internet to learn from then.

I think that with modern resins the process could be much more straightforward, and could scale relatively easily, and am thinking about having another go, but still on a small scale. Seeing how well those bird feathers look, maybe try it on some of them ( I like to pick interesting ones up), fishing flies, small animal skeletons, little fossils, recovered bullets, small things like these. As well as the bugs, beetles and flora, and other natural bits and pieces collected on holidays.

Even then, just a drinking glass sized mould is going to require maybe 1/3 litre of resin, which is over £15 for the specialist stuff in modest quantities, so it could become an expensive hobby, particularly when learning again.

Most of my old Plasticraft pieces, which were all gifted to others, but mostly still in the family, have yellowed, but by that I just mean turned a light honey colour. The biggest paperweight, that sits on my Father's desk, is exposed to sunlight most of the day, and has "honeyed" the most, but if anything that adds to it's charm. The little pieces that sit in drawers etc. are still water-clear, so I can't complain, after over 40 years. Who knows how the modern materials will compare, on similar timescale. ?

I wouldn't be afraid of using the cheaper polyester clear-cast resins nowadays, even though the modern epoxy stuff, and low-odour things are probably more easy.
 

John_R

Well-Known Member
The good resins are not cheap. I have more recently built fishing rods, lures and boats. The resin is a significant part of the budget.
 

Peter Eaton

Well-Known Member
Ahh the very thing I am doing tomorrow is making HDPE plastic moulds for resin as I wish to expand my stabilization of materials in my vacuum chamber to stabilised materials incapsulated / moulded with two pack epoxy resin which I have just purchased, not cheap, that's for sure. This will enable me to make some stunning knife handles with wood and other materials.
 

Sharpie

Well-Known Member
Been doing more research. Found a recent video from elichem explaining how to use their deep casting resin making tables, looks like some of the techniques could be quite applicable to casting a skull:


Klenchblaize, looking again at your bird, could it be that it was cast inside a perspex/acrylic fabricated box, which is now a permanent part of it, I think I see the lines ? Perhaps you are right, getting bubbles out of the feathers might be helped by pulling a modest vacuum too, just speculating.

Making such boxes is DIY able. That way you could make them just the right size to fit a particular skull, and save on a lot of finishing, other than the final surface of the resin. Also providing the "floating" effect, I.e. the object rests on the bottom of the box without needing a first layer of resin to suspend it. Or just get someone like Clear Plastic Sheets | Clear Acrylic Sheet | Sheet Plastics to supply the pieces already cut to size, no waste, all you need to do is weld them together, which doesn't seem too daunting, with the correct cement.

Possibly if you applied release wax inside you could even get them off afterwards, if you somehow machined and put them together with a slight taper, used a thin sheet, and did some thumping to spring the block out once it was thoroughly cured. Even if they came apart, you could cement them back together again easily enough I think.


The wood stabilisation processes seem fascinating, I've now even learned a little about "Cactus Juice", which seems like clever stuff. Perhaps you could even do a gunstock and combine synthetic durability and weatherproofness with wood beauty ...

Maybe for a skull, get creative and start with a background made from a beautiful piece of wood sitting on a natural coloured layer, even artistically coloured, swished about, foreground, background, sky, appropriate to the habitat, cut to include bark and ragged edges (no, not a mass produced shield, or simple slice of log), surrounded by other natural objects appropriate to the habitat, acorns, flowers, heather, some browse, etc. Even a "last bite," the case and recovered bullet if you have it, and medal, but that might be a bit kitsch. Who wants to look at the back of the skull anyway ? But I'm getting carried away ...
 

Sharpie

Well-Known Member
TBH, whilst it is certainly possible to make great looking display pieces from resin casts, I am not convinced that they will stand the test of time, if that matters to you. One of the site owners is an absolute expert in the traditional methods, and how to maintain them, and they have stood the test of time, with some maintenance. Once you have embedded something into a chunk of resin, whatever is flavour of the month, or cheapest, well do it right, with materials that are stable, and it might just work, but I doubt that anyone really knows how it's going to pan out. Maybe an enduring heirloom to pass on, possibly not, just a deteriorating chunk of unstable badly mixed resin. There's no going back.That may not matter to most of us, in our lifetime, and I like to be optimistic about modern materials.
 
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Peter Eaton

Well-Known Member
Been doing more research. Found a recent video from elichem explaining how to use their deep casting resin making tables, looks like some of the techniques could be quite applicable to casting a skull:


Klenchblaize, looking again at your bird, could it be that it was cast inside a perspex/acrylic fabricated box, which is now a permanent part of it, I think I see the lines ? Perhaps you are right, getting bubbles out of the feathers might be helped by pulling a modest vacuum too, just speculating.

Making such boxes is DIY able. That way you could make them just the right size to fit a particular skull, and save on a lot of finishing, other than the final surface of the resin. Also providing the "floating" effect, I.e. the object rests on the bottom of the box without needing a first layer of resin to suspend it. Or just get someone like Clear Plastic Sheets | Clear Acrylic Sheet | Sheet Plastics to supply the pieces already cut to size, no waste, all you need to do is weld them together, which doesn't seem too daunting, with the correct cement.

Possibly if you applied release wax inside you could even get them off afterwards, if you somehow machined and put them together with a slight taper, used a thin sheet, and did some thumping to spring the block out once it was thoroughly cured. Even if they came apart, you could cement them back together again easily enough I think.


The wood stabilisation processes seem fascinating, I've now even learned a little about "Cactus Juice", which seems like clever stuff. Perhaps you could even do a gunstock and combine synthetic durability and weatherproofness with wood beauty ...

Maybe for a skull, get creative and start with a background made from a beautiful piece of wood sitting on a natural coloured layer, even artistically coloured, swished about, foreground, background, sky, appropriate to the habitat, cut to include bark and ragged edges (no, not a mass produced shield, or simple slice of log), surrounded by other natural objects appropriate to the habitat, acorns, flowers, heather, some browse, etc. Even a "last bite," the case and recovered bullet if you have it, and medal, but that might be a bit kitsch. Who wants to look at the back of the skull anyway ? But I'm getting carried away ...
I doubt you would be able to do something like a stock as once cured in the oven the wood will have lots of rock hard excess resin on it along with tin foil stuck to it. I cured some blocks last week and spent 30 minutes removing the junk from them today with a wire brush before taking them to the sanding disc, this stuff really does set like rock and requires 36 or 40 grit initially. Someone asked me if an airgun stock could be done and I said it would most likely 'drink' lots of resin, need a huge vacuum chamber and would he really want to be using 40 grit on his stock? If it is possible somehow it would only really work on the worst wood, ie 'punky' wood , very porous and light in weight as the better and denser the wood the less resin enters the wood. The wood I just stabilised had good figuring but very light in weight, and full of voids, perfect for stabilising and then casting in resin to fill the voids.....oh and wood has to be cooked in the oven for 24hr to be zero percent moisture for the process to work correctly, likely to crack a stock
 

Klenchblaize

Well-Known Member
I doubt you would be able to do something like a stock as once cured in the oven the wood will have lots of rock hard excess resin on it along with tin foil stuck to it. I cured some blocks last week and spent 30 minutes removing the junk from them today with a wire brush before taking them to the sanding disc, this stuff really does set like rock and requires 36 or 40 grit initially. Someone asked me if an airgun stock could be done and I said it would most likely 'drink' lots of resin, need a huge vacuum chamber and would he really want to be using 40 grit on his stock? If it is possible somehow it would only really work on the worst wood, ie 'punky' wood , very porous and light in weight as the better and denser the wood the less resin enters the wood. The wood I just stabilised had good figuring but very light in weight, and full of voids, perfect for stabilising and then casting in resin to fill the voids.....oh and wood has to be cooked in the oven for 24hr to be zero percent moisture for the process to work correctly, likely to crack a stock
Sounds like someone who enjoys the additional wight of a moderator!

A stabilised rifle stock would be very heavy. Do you not agree?

K
 

Sharpie

Well-Known Member
Sounds like someone who enjoys the additional wight of a moderator!

A stabilised rifle stock would be very heavy. Do you not agree?

K
The amount of weight increase depends on the percentage of resin to wood after impregnation. Also how deeply the resin actually penetrates.

Stocks are usually dense hardwood, even walnut, which I think is the least dense commonly used (though poplar is now being used for air rifles to further reduce weight, maybe not adequate for recoiling things).

Beech, for example is about the densest wood used for stocks. 700-900 g /litre. Walnut 650-750. Poplar 350-550. Epoxy is 1200-1400. If somehow even fully impregnating it all the way through, which I presume would not be possible with self-curing epoxy on a thick piece, unless it had an extremely long working time, might introduce what, 5 or 10%, I dunno.

Here's an estimate:

1 litre = 700 g walnut, totally impregnate with 0.1 litre of resin (10%) = 130 g. Final weight 830 g i.e. 19% increase. NB, this doesn't mean the rifle overall got 19% heavier, and it's not much different from e.g. beech vs. walnut. But this is based on a 10% impregnation assumption that I just guessed at.

Maybe Peter Eaton could advise, cut identical sized samples from a test piece, before and after, weigh, compare.

Worth doing it for the improved properties, not just to make a knife handle or pen ? Well it was just a thought, but having a totally waterproof, environmentally stable, stronger stock that is immune from the usual dents and scratches, takes a beautiful finish, and requires no maintenance might attract some, if it could be done during manufacture to the blank. I can see that trying to do it to one afterwards would be more of a challenge, and working on such a stock blank might need some upgrades to the cutters on the automatic machines used to mass-produce them, and maybe re-programming of the lasers nowadays used for chequering. Hardly worth it for mundane wood, but for premium stocks perhaps.


By the way "Cactus Juice" is not epoxy. It's an acrylic resin, solvent-free, formulated to penetrate for as long as it takes, then be cured by heating to 100 C, not by mixing with a catalysing hardener. Even the re-usable excess cleans up with just water, and lasts for months, with the secret activator, or years before it has been mixed. So it's said. A clever product:

Mixed Methacrylate Esters Proprietary Mixture 90-95
Surfactant Proprietary Mixture 5-10

According to the MSDS at https://www.conestogaworks.com/articles/Cactus Juice MSDS.pdf

"Stick Fast" stabiliser seems like much the same thing, at similar price.
 

Klenchblaize

Well-Known Member
The amount of weight increase depends on the percentage of resin to wood after impregnation. Also how deeply the resin actually penetrates.

Stocks are usually dense hardwood, even walnut, which I think is the least dense commonly used (though poplar is now being used for air rifles to further reduce weight, maybe not adequate for recoiling things).

Beech, for example is about the densest wood used for stocks. 700-900 g /litre. Walnut 650-750. Poplar 350-550. Epoxy is 1200-1400. If somehow even fully impregnating it all the way through, which I presume would not be possible with self-curing epoxy on a thick piece, unless it had an extremely long working time, might introduce what, 5 or 10%, I dunno.

Here's an estimate:

1 litre = 700 g walnut, totally impregnate with 0.1 litre of resin (10%) = 130 g. Final weight 830 g i.e. 19% increase. NB, this doesn't mean the rifle overall got 19% heavier, and it's not much different from e.g. beech vs. walnut. But this is based on a 10% impregnation assumption that I just guessed at.

Maybe Peter Eaton could advise, cut identical sized samples from a test piece, before and after, weigh, compare.

Worth doing it for the improved properties, not just to make a knife handle or pen ? Well it was just a thought, but having a totally waterproof, environmentally stable, stronger stock that is immune from the usual dents and scratches, takes a beautiful finish, and requires no maintenance might attract some, if it could be done during manufacture to the blank. I can see that trying to do it to one afterwards would be more of a challenge, and working on such a stock blank might need some upgrades to the cutters on the automatic machines used to mass-produce them, and maybe re-programming of the lasers nowadays used for chequering. Hardly worth it for mundane wood, but for premium stocks perhaps.


By the way "Cactus Juice" is not epoxy. It's an acrylic resin, solvent-free, formulated to penetrate for as long as it takes, then be cured by heating to 100 C, not by mixing with a catalysing hardener. Even the re-usable excess cleans up with just water, and lasts for months, with the secret activator, or years before it has been mixed. So it's said. A clever product:

Mixed Methacrylate Esters Proprietary Mixture 90-95
Surfactant Proprietary Mixture 5-10

According to the MSDS at https://www.conestogaworks.com/articles/Cactus Juice MSDS.pdf

"Stick Fast" stabiliser seems like much the same thing, at similar price.
I'm basing my assertion on the weight of stabalised knife scales albeit burr is naturally porous (full of inclusions) so how deep the resin penetrates is unclear to me.

Done correctly they are subject to both vacuum and baking. The size of a stock would make this a challenge in terms of equipment but I'd like to see an example.

K
 

Sharpie

Well-Known Member
More obsessive research (I also have a chemical engineering background):

Properties of various esters https://www.conestogaworks.com/articles/Methacrylate-Esters-Safe-Handling-Manual-2008.pdf

Choose the ones that are safe, easily cleaned with water, and allowed to be flushed down the drain (actually not), if you can get your hands on some, rather than buy it it industrial quantities. You might be able to guess what might be in "Cactus Juice".

This is what from which big sheets of clear acrylic are cast, or otherwise made from. Glass transition temperature 105 C, so you could even bend a shotgun stock to fit after impregnation. No chance with epoxy resin.

I'm guessing that the "secret-sauce" activator is Ammonium Persulphate.

.

BTW, this is much less dense than epoxy, maybe 800 g / litre.
 
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Rasputin

Well-Known Member
Thinking about having a go at something like this

I have a table top already which has a chunk of glass in it and would be perfect for it so long as I sealed it up.
 

Peter Eaton

Well-Known Member
More obsessive research (I also have a chemical engineering background):

Properties of various esters https://www.conestogaworks.com/articles/Methacrylate-Esters-Safe-Handling-Manual-2008.pdf

Choose the ones that are safe, easily cleaned with water, and allowed to be flushed down the drain (actually not), if you can get your hands on some, rather than buy it it industrial quantities. You might be able to guess what might be in "Cactus Juice".

This is what from which big sheets of clear acrylic are cast, or otherwise made from. Glass transition temperature 105 C, so you could even bend a shotgun stock to fit after impregnation. No chance with epoxy resin.

I'm guessing that the "secret-sauce" activator is Ammonium Persulphate.

.

BTW, this is much less dense than epoxy, maybe 800 g / litre.

I can see you are tempted by the dark art of resin....:)….Be warned , its a never ending path, a bit like shooting as very addictive and you wonder where all your money went :eek:....I just bought more dyes and effects powders for my casting today. With regards to the juice, its a pain to source unless you want 200 gallons from China, other wise its Cactus Juice, afraid I lost my contact for the stuff I had. I did see a guy using stuff used for coating the industrial windings on motors but dread to think what it was.
 
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