Hi
I’ve been making a load of things (mostly rings) with either epoxy and/or PU resin. Some clear with inclusions and some opaque and some a mixture of the two. My questions concern the finishing of them. I understand epoxy resin isn’t UV resistant so clear would yellow over a period of time. Also, I find that I don’t always get the best finish when using silicone moulds. Therefore I need to coat each piece with a clear coat or a lacquer. I’ve had a look on EC website and forum and have found several possibilities. But which one would be best for my purpose?

1. A resin clear coat. Would I sand the piece then apply this to one side, let this dry then apply to the other side? Can it be painted on without brush marks? Can I then buff it on a buffing wheel?

2. GC50. Does this work on the same principle as a resin clear coat as above? Again would I apply it in sections, can it be painted on without brush marks and can it be buffed on a wheel?

3. I’ve also read on here about a 2 part clear lacquer used on cars. Is this just a general acrylic or is there a specific one that I should be looking for? What does the ‘2 part’ refer to? Would it bond ok with PU and epoxy?

Basically, im looking for the best method for UV protecting as well as achieving a high gloss finish on small jewellery pieces? I know some puritans out there may well suggest going through the sandpaper grits but I’ve tried this and it takes far too long with only barely adequate results?!

Hoping someone can point me in the right direction. Much appreciated. X

1. Ec got a coating epoxy, wich should suit you needs. Best way to get it really even would be to spray paint it. But wiping it on with micro fibre cloth can give good results, too. This resin should be uv resistant.

2. This isn't made for coating applications. I don't know if it will do well in this case. Usually polyester doesn't stick well to epoxy. at least, gc 50 should cure tack free, unlike usual polyester.

3. 2 part means, that you have to mix two components together before you apply the laquer. 2 component lacquer is far more durable and chemically  resistant than any 1 component (rattle can) laquer. The uv resistance and gloss propertys should be at least as good as the epoxy coating resin, if not better.

You could buy uv blocker additive for epoxy resins. If you could get a good finish from the mould, you would not need any surface treatment.

+x

 

oekmont - 12/27/2017 11:01:17 AM

1. Ec got a coating epoxy, wich should suit you needs. Best way to get it really even would be to spray paint it. But wiping it on with micro fibre cloth can give good results, too. This resin should be uv resistant.

2. This isn't made for coating applications. I don't know if it will do well in this case. Usually polyester doesn't stick well to epoxy. at least, gc 50 should cure tack free, unlike usual polyester.

3. 2 part means, that you have to mix two components together before you apply the laquer. 2 component lacquer is far more durable and chemically  resistant than any 1 component (rattle can) laquer. The uv resistance and gloss propertys should be at least as good as the epoxy coating resin, if not better.

You could buy uv blocker additive for epoxy resins. If you could get a good finish from the mould, you would not need any surface treatment.

Thanks so much for the response Oekmont. I will try the coating epoxy with a microfiber cloth as you suggest. I'm assuming it will be a bit thicker than normal resin so it will not 'pool' on the surface. Do I need to sand the piece first in order for it to grip?
I also read on here about a new casting epoxy that EC have been working on and are planning on releasing in January. Does anyone have an approximate due date?
I wish I could just buy a UV additive for my existing resin but alas some of my moulds have got several tiny scratches on them - is there a way to get rid of them and re-gloss the surface of silicone does anyone know?

Hi Wends,

Sorry for the late reply, we're officially closed over the Christmas break but I'm just checking in on the forum so see if I can help out at all over the break. I can see that Oakmont has provided you with some helpful advice.

UV stability of epoxy resins is a *big* subject with no 100% definitive answers. What I can do though is explain honestly exactly where the chemistry of our products is up to and what my own recommendations would be.

First off, no epoxy resin is 100% UV stable. Some (especially a select number of modern resins) have excellent resistance to UV light. Others, which have not been designed for the purpose or which use outdated chemistry, have very poor resistance to UV light and within a month or less of direct exposure. The best of the modern UV resistant epoxies that we sell (such as ArtResin, XCR and GlassCast) have excellent resistance to UV and show very little yellowing after accelerated UV exposure equivalent to thousands of hours of direct sunlight. These special UV resistant resins do already have the 'blockers' in that oakmont was talking about and so you would not need to (and we wouldn't not recommend that you do) add any further additives to the resin (it is likely to affect their clarity). I would say that for the indoor/occasional outdoor environment of jewellery, you would be extremely unlikely to see any noticeable yellowing of any of these resin systems within a several-year timeframe. Therefore, if you're working with any of these resins then we would not suggest that you would need to coat them in order to provide further UV resistance when you're making jewelry items.

Oakmont mentioned our new casting resin which would certainly be a very good suggestion for you. We actually have two new UV stabilised epoxy casting resins launching in January 2018 (they are running very late and we due to launch months ago but they are now in stock and will be available to buy in January). The product for you would be our "GlassCast 10" which we've developed specifically for smaller creative applications like jewelry. The resin is water clear, highly UV stable (see notes above), self-degassing and cures with a super glossy finish. Pricing will be very similar to our current GlassCast product. We have had samples of this resin in our UV exposure unit since the summer where they have been clocking up thousands of hours in intense UV light and show very little discolouration even in this extreme UV environment.

Another point you mentioned were that you were using some polyurethane casting resin. It's worth pointing out that our Water Clear Polyurethane Casting Resin is 100% UV stable and will not discolour under any circumstances, exposure or timeframe. Clear polyurethanes are more complicated to work with than epoxies and so generally we regard it as a 'professional' material only. Reasons for this include the fact that ideally it needs degassing in order to be bubble-free, there are many more materials that the resin is incompatible with (both moulds and inclusions) and you need to be more careful with your PPE when handling the uncured product. However, if you master working with it then the results can be incredible.

The last thing you mentioned was improving the glossiness of your finished pieces. For this, if you're working with either epoxy of polyurethane casting resins then I would suggest getting a polishing wheel (should be able to pick something up either quite cheaply or more likely a good second hand one) and then using a polishing compound like the Pai Cristal NW1 which is designed for composite materials, especially hard resins like epoxy.

I hope this helps but I would be very happy to answer any other questions you may have.

Have a great New Year.

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Hi Matt

Thanks so much for that! I love that you’re on holiday and away from work but you can’t keep away totally. That to me is true success as it means you love your job. Awesome!

Thanks interesting reading about your resins and the modern ones being sufficient for my needs. I get most from either EC or east coast fibreglass so I’m sure they will already be adequate. Sometimes the surface of my mould has been compromised though and I need to sand it down and refinish it which is mostly whim after a surface treatment.

I do have a hobby polishing machine which is a bit like a bench grinder set up. There are so many types of polishing wheel and pastes/creams/compounds etc available for different purposes (much like resin itself I suppose) that again, I’m struggling to know which is best for my needs. Especially when some forums suggest using a metal polish on resin etc. I shall put in an order for the compound you mention above as soon as your new resin is available so I can get them together.

I’ve read the how to use part where it links to the polishing pads you recommend using with it. Do you have any recommendations for similar pads that will fit on a bench grinder type set up. I.e. with the hole in the middle f the pad? There are so many to choose from ( felt, wool, foam, cotton, calico, stitched, unstitched....) I would rather get advice first. I could get the ones you recommend which will fit to my Dremel but I’d much rather have both hands free.

I would love to attend some sort of overview workshop where I could learn the do’s and dont’s in theory and in practice.

Thanks also for th3 heads up re clear PU resin. I did have some but stopped using it when I read on someone’s blog that hobbyists should avoid it all costs due to the PPE requirements. Should I wish to dispose of the unused bottles I am assuming I can take them to the council tip and tell them what 5hey are so they can dispose of them properly?

Thanks again for your advice, I really appreciate it. Happy New Year too!

The way to dispose of unmixed resins is to mix them and allow them to cure.  Cured resin is in most areas not classed as hazardous waste and as such can be disposed of in general waste disposal.  It is best to check locally to be sure though in case your local rules are different.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Any advice re the polishing mops part of my question? I’m just looking at the choices available on the Cookson gold website and there are loads! I really don’t know where to begin!

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Many thanks Matt. I appreciate your reply. Looks like a bit of experimentation is in order like you suggest. I think I’ll order the recommended foam pads for my Dremel so I can see how they perform with the NW1 and what ‘action’ I’m looking for. Then I can compare it to some wheel mops.