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Topic: Polyester Resin Issue - HELP!!  (Read 3665 times)
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sheena.lee
« on: August 24, 2009 07:49:20 PM »

This probably has been asked before but I can't find anything super specific to what I need.

Three days ago I tried my hand at polyester resin (castin craft).  I did some embedding with different objects and they turned out okay except for 1 detail... the exposed surface (the back) is STILL sticky.  It's been over 72hrs.  Also the front part (that was touching the mold) got some finger prints after I took a few out last night.
Now would be an appropriate time to mention that I used some soap molds and no mold conditioner/release, mainly because craft store sin Montreal pretty much SUCK.  (sorry omer deserres... i can't love you anymore.)  So basically I was unable to get most of the casts out of the molds, but that's not really the issue... they didn't turn out that well anyway and I don't foresee myself using them for other projects.

SO, I bought some siligum (fun!!) and made a couple flexible molds.  That's 1 issue solved.

How do I get rid of the stickiness issue?  The finger prints look terrible...  I really want to know if I did something wrong before I mix some more resin and run into the same problem...  Help!! Sad
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smittenheart
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« Reply #1 on: August 24, 2009 08:25:23 PM »

cant say there is..I know some have coated it with sealer but the prints may stay even after the sealer is cured..

as for the why?? it could be a slight mismeasurement with the the 2 liquids and maybe not enough stirring..

if its not cured after 3 days then something is a little off..

good luck..and silicone molds work perfectly..good luck Smiley cant wait to see what you come up with..
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its ME!!
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Diane B.
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« Reply #2 on: August 25, 2009 10:56:49 AM »

Quote
How do I get rid of the stickiness issue?  The finger prints look terrible...  I really want to know if I did something wrong before I mix some more resin and run into the same problem.

You probably didn't do anything "wrong" (though you might have--incomplete mixing, too much humidity, etc) but it's important to understand that polyester resins don't cure thoroughly in the presence of air (like epoxy resins will), so the side of the resin exposed to air while in the mold can have surface problems.  
Certain things can increase that problem, but also some things can be done before or after curing to fix or prevent the problem.  Rather than explaining them all here, check out the Polyester Resin category on this page of my site for loads of details:
http://www.glassattic.com/polymer/other_materials.htm

P.S.  You could instead use a type of epoxy resin that has been tweaked so it can be used in deep molds (which regular epoxies don't usually work well in), but that particular resin (Easy Cast) has its own problems after curing in that its surface can become softer, and it can even become flexible if thin, when exposed to heat--even body heat.


HTH,

Diane B.

« Last Edit: August 25, 2009 10:58:32 AM by Diane B. » THIS ROCKS   Logged

POLYMER CLAY "ENCYCLOPEDIA" 
http://glassattic.com/polymer/contents.htm
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sheena.lee
« Reply #3 on: August 25, 2009 06:01:45 PM »

Thanks for the info guys!  The epoxy resin sold in craft stores here are the store's own brand called Vitra-Laque.  I'm not sure if it's designed for deep molds, but "laque" to me sounds like "lacquer" which makes me think that it's supposed to be used as a coat and not in a mold.

I tried mixing some more polyester resin this evening.  I mixed it really well and made sure that the resin was completely uniform before pouring it.  It's also less humid so I hope that helps too.  So far they seem to have turned out much better already, I made a really deep one that became fairly solid very quickly, so I'm hoping at least that one turns out if none of the others do.

Thank you for the link Diane!  I had actually stumbled upon your website yesterday afternoon but I was at work and couldn't look at it for very long.  I'm going to read some more tonight.

My idea is, if its slightly sticky, I could use some sort of sealer on both sides of the cast handling it only with rubber gloves to minimize finger prints.  Would that work?

Is it recommended to use the same brand of sealer? Or would any kind of clear coat work?  I know that craft stores around here don't sell anything except the resin and the catalyst/hardener.
« Last Edit: August 25, 2009 06:02:38 PM by sheena.lee » THIS ROCKS   Logged
Diane B.
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« Reply #4 on: August 26, 2009 08:32:55 AM »

Quote
My idea is, if its slightly sticky, I could use some sort of sealer on both sides of the cast handling it only with rubber gloves to minimize finger prints.  Would that work? . . . Is it recommended to use the same brand of sealer? Or would any kind of clear coat work?  I know that craft stores around here don't sell anything except the resin and the catalyst/hardener.

If it's sticky, you can just wait longer to see if that fixes the problem, or you could sand and buff the sticky side, or you could apply a coat of epoxy resin (not polyester resin) which will not cure sticky and is commonly done or clear polyurethane (water-based, gloss) probably... or you could do one of the preventive things suggested on the page I linked to.  Your whole object shouldn't be sticky btw (unless there were temporary problems with mixing, humidity, etc)... the sticky parts should be only the side that cured next to the air which would usually be the "back" side.

And you definitely don't have to use the same brands (for almost anything).

P.S.  I assume, like you, that the Vitra-Laque is a craft epoxy resin since using epoxy resins to coat something is often described as the "equivalent of 50 layers of polyurethane" etc, and finishes are sometimes referred to as laquers (in English, they sometimes have a more specific meaning, but I know the German versions of clear water-based acrylic sealers for polymer clay had "lac" in their German names).

Diane B.
« Last Edit: August 28, 2009 08:27:39 AM by Diane B. » THIS ROCKS   Logged

POLYMER CLAY "ENCYCLOPEDIA" 
http://glassattic.com/polymer/contents.htm
few of my photos
http://s96.photobucket.com/albums/l163/DianeBB
(had to move them from YahooPhotos, so many now without captions)
sheena.lee
« Reply #5 on: August 26, 2009 06:01:13 PM »

Thanks for the info!  I started reading your page after I posted and realised most of my questions were answered there.  Thank you for taking the time to answer anyway Smiley

Only the exposed side is sticky, the rest is okay - I just figure that it would be nicer to spray the whole thing with glossy stuff.

The pieces I made yesterday turned out A LOT better than my first try so far, so I'm feeling a bit more confident!

Thanks again Smiley
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glitterkick
« Reply #6 on: August 27, 2009 11:32:38 AM »

Here's my experience working with Castin' Craft, just for your info. I used it many, many, MANY times and the backs were always tacky. The only thing that helped was using the Castin' Craft brand surface hardener and doing two pours. So the initial pour, wait for it to harden, then do a thin second pour mixed with the surface hardener. The only bad thing about the hardener is that it gives the resin a slightly cloudy appearance. If you are mixing colors with the resin, it's not noticeable, but definitely is if you want it clear.

Other than that, gluing a small piece of felt of the back of my pieces was my only other solution.

I use Easy Cast brand resin now and love it, I would never use the Castin Craft again. I can work with it much longer before it starts to get tacky and the surfaces and backs are always very smooth and non-tacky.

Best of luck!
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sheena.lee
« Reply #7 on: August 27, 2009 05:18:23 PM »

Here's my experience working with Castin' Craft, just for your info. I used it many, many, MANY times and the backs were always tacky. The only thing that helped was using the Castin' Craft brand surface hardener and doing two pours. So the initial pour, wait for it to harden, then do a thin second pour mixed with the surface hardener. The only bad thing about the hardener is that it gives the resin a slightly cloudy appearance. If you are mixing colors with the resin, it's not noticeable, but definitely is if you want it clear.

Other than that, gluing a small piece of felt of the back of my pieces was my only other solution.

I use Easy Cast brand resin now and love it, I would never use the Castin Craft again. I can work with it much longer before it starts to get tacky and the surfaces and backs are always very smooth and non-tacky.

Best of luck!

Oohh thanks for the insight!  I'm going to have to try to find a craft store in my area that has better selection so I can experiment more.

My most recent pieces actually turned out decent.  I left them 24hrs and then glossed them with some Eberhard Fabre clear coat (it was all I had...) and they look pretty nice.  I think it also helps that I didn't have to cut them out of the mold, but I'm pretty happy with the turnout overall.

Cheesy
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karen09
« Reply #8 on: September 13, 2009 09:20:37 PM »

i have never tried using resin before and i had finally gotten enough to courage and venture out and try it, but now im scared.

i bought this same kind after i bought the wrong kind to begin with. I exchanged it and got this kind. so, is this castin craft not good for small project like pendants? for example, i have this silicon ice cube tray that i got in the dollar spot at target a while back. the little heart shaped molds are about half an inch deep and no more than inche wide at the widest part. Should i get easy cast instead?

Also im not sure i understand the instruction on how to mix. theyre kind of unclear, can anyone please help me out. thanks!
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Diane B.
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« Reply #9 on: September 14, 2009 12:01:48 PM »

karen09, the bottom line is that Castin' Craft makes two clear craft resins... a polyester resin called Castin' Craft Clear Polyester Casting Resin, and a "tweaked" epoxy resin called Easy Craft.  
Both will work fine in molds (the right kinds of molds anyway**) and are the only types which will reliably work well in deep molds.  (And they both work fine in small molds for making pendants/etc.)
**silicone or other molds must be "shiny" to work best... otherwise the surface of the resin won't come out shiny

Castin' Craft's polyester resin will work the best of the two, but needs more ventilation than Easy Cast.  
Castin' Craft's Easy Cast works okay but may stay soft-ish and/or be slightly sticky especially when exposed to heat (even body heat) and also any thin areas will be flexible.
So basically, you just have to decide which you want to use.  If you're really scared, you might want to start off with Easy Cast, then switch to the better-performing polyester resin once you get your sea legs.

The molds you have are fairly shallow though, so you might even be able to use a regular epoxy resin (Envirotex Lite is probably the most common brand) or even a 2-part epoxy glue in them (the clearest, I hear, is the Devcon "2-Ton", 30-min set).  If you use a regular epoxy resin, you might (or might not) need to do the cast in several layers of 1/8" at a time, curing at least partly between each layer, since too much thickness can cause problems with clarity, etc.

As for mixing resins, check out the subcategory on Preparing, Sealing, Mixing resins (under the Epoxy Resins category) on this page at my site for info, tips, lessons, video lessons, etc:
http://www.glassattic.com/polymer/other_materials.htm

You'll also want to check out various subcategories,the Polyester Resins category for lessons and info, which include these links:

Tap Plastic's video lesson on using a polyester resin in a (large) mold to embed pennies in one of the layers
http://www.youtube.com/watch?v=Y0Wp9CmSKFY
(mixing of epoxies is similar but for best results pour "mixed" parts into a new container to avoid having any tiny bits of unmixed resin in the mold)
many other video lessons on using epoxy and polyester resins at YouTube:
http://www.youtube.com/results?search_query=resin+jewelry
(...be aware though that many videos and written lessons identify polyester resins as epoxy resins, and vice versa... you can tell which are really being used though because epoxies are mixed one-to-one, and polyesters are mixed a lot of resin to a few drops of catalyst)

P.S.  If you didn't notice, there is a looong "sticky" thread relating only to discussion re resin at the top of the Jewelry & Trinkets Completed Projects board (called the Random Resin Questions Thread or something like that) which has lots of info from the past and new questions/posts all the time... here's a direct link:
https://www.craftster.org/forum/index.php?topic=10667.0

And here are some posts I've written before here about using resin in general too:
https://www.craftster.org/forum/index.php?topic=275238.msg3112408#msg3112408
https://www.craftster.org/forum/index.php?topic=293667.msg3341730#msg3341730
https://www.craftster.org/forum/index.php?topic=254029.msg3522191#msg3522191


HTH,

Diane B.

« Last Edit: September 14, 2009 01:04:10 PM by Diane B. » THIS ROCKS   Logged

POLYMER CLAY "ENCYCLOPEDIA" 
http://glassattic.com/polymer/contents.htm
few of my photos
http://s96.photobucket.com/albums/l163/DianeBB
(had to move them from YahooPhotos, so many now without captions)
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