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Topic: The random RESIN question thread!  (Read 373095 times)
Tags for this thread: resin , mold , catalyst , resin_problems  Add new tag
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amaliadc
« Reply #1630 on: December 25, 2010 09:51:26 AM »

I left them for 24 hours. Thinking perhaps I should have left them longer. I assumed they were about ready, because it looked like they were separating from the mold.

I bought Castin Craft poly resin. I used an ounce per layer, 5 drops of catalyst for the first and 4 drops for the second layer.

I attached a photo. You can see were they cracked, and on the first coaster you can see a weird residue and such on the top.

http://i7.photobucket.com/albums/y282/ImAmaliaBedelia/photo6.jpg

They're also a bit sticky on both sides.

« Last Edit: December 25, 2010 09:54:28 AM by amaliadc » THIS ROCKS   Logged
Diane B.
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« Reply #1631 on: December 25, 2010 10:29:12 AM »

Okay, so what you used was the "polyester" type of clear arts & crafts resin...the main brand of that is still Castin Craft Clear Polyester Casting Resin (a mouthful).  On the other hand there are many brands, and even some types, of epoxy resin.

Polyester resins have some advantages and some disadvantages compared to epoxy resins though...for example, they:
...are less safe for lungs/breathing, and stinky
...are less strong after curing (more brittle)
...will not thoroughly cure in the presence of air (so the side curing next to air may be or stay sticky, or be ripply, etc)
...will become rubbery if ever subjected to temperatures over 200F later
...are very fiddly for getting the right proportion of catalyst to resin to each project (see below)
The advantages are that it can be poured deeper than 1/4-1/2" and so make "taller" casts than regular epoxy resins, are a bit cheaper, and often will be less subject to later yellowing from UV light (if not sealed with UV-resistant polyurethane, etc).  Regular epoxy resins should only be used at those thinner pour depths or shallower** (they're also used as "coatings," applied with brushes or dipped, etc).  

**There are tweaked epoxy resins though at least that can be cast deeply, like Easy Cast.  Easy Cast will get a softer surface though if exposed to (even body) heat, and if thin can be flexible.

Here are a couple of things from the page at my site I gave you before about cracking in polyester resins:
.....Too much catalyst makes resin set faster, but also creates too much heat; this can lead to fracturing of resin, or fading of embedments or distortion of vinyl-based or styrene-based plastic molds.
...and similarly, with some overlap:...because heat accelerates chemical reactions, all resins cure from the INSIDE out...using too much catalyst will overheat the casting (excessive exotherm), causing resin shrinkage and cracking, and discoloration ...but exotherm can be controlled by adjusting the amount of catalyst used, the volume or thickness of resin poured (at one time), and ambient temperature (the higher the temperature, the faster the gel ...too fast a cure will cause fractures.)
...thicker (taller) pours require less catalyst because a thick casting retains heat... whereas a thin section dissipates the heat requiring more catalyst.
...If the room your'e working in is below 65 degrees F, it will slow down the curing.  If the room is over 75 degrees F, it will accelerate the curing and may cause yellowing and/or cracking.


Sometimes resins will take longer than 24 hrs before easy removal too (even in the "right" molds or with the right releases), especially due to temp and humidity, etc, sometimes even age of resin (they definitely have a shelf life).  That might be up to 48 hrs or even longer, but in general when done right polyester resins should be able to be popped out of their molds in 4- 24 hrs though probably still not thoroughly cured yet.

Keep in mind that coasters can be hard to do with resin because of the facts that hot and or wet liquids may be sitting on them for long periods of time, so that alone can cause problems if there's direct contact.

P.S.  Here's just one video showing how to use polyester resin in a mold with embedments... it's using the Tap Plastics brand of polyester resin:
http://www.youtube.com/watch?v=Y0Wp9CmSKFY
There are many more videos at YouTube showing the use of clear "resins" that can be helpful too, but be aware that sometimes the makers will say they're using epoxy resin when they're using polyester resin (or vice versa) or not realize that Easy Cast is an epoxy resin but different than the other epoxy resins, or something similar.  There will also be a load of videos at YouTube where clear polyester resin is used between layers of fiberglass cloth and that's not what you want to do (and often won't be using an art/craft quality polyester resin).

And here are a bunch of lessons on making coasters with "resin" (both kinds, several ways) though I haven't checked them all out:
http://www.google.com/search?q=how+to+make+coasters+with+resin+mold
http://www.google.com/search?q=how+to+make+coasters+with+resin

.

 
« Last Edit: December 25, 2010 10:42:55 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)
amaliadc
« Reply #1632 on: December 25, 2010 04:12:17 PM »

Thanks for the info!

Sounds like either I switch to epoxy or abandon the project, given my current environment. I'll try one more time when I get the new mold and let it cure longer, otherwise I guess I don't have the knack for resin Wink

I am considering just using mod podge to apply the photos to these coasters....does anyone know if that's possible, given it has a round insert (I assume on the back too)?

http://www.elegantquilling.com/product/EQ20042/Hexagon-Coaster.html
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Diane B.
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« Reply #1633 on: December 25, 2010 05:29:51 PM »

ModPodge (or thinned down permanent white glue) is the usual thing used to seal porous materials before putting in resin and also the adhesive often used to "glue down" a photo or other paper image to the back of a "cell" when doing that, and it's perfectly fine to use it just to glue down a photo/etc to a permanent back.  You can then also use something like epoxy resin or gloss polyurethane/Varathane/etc or vinyl floor polish** or other things as a thick coating on top, particularly if you leave the whole thing inside a cell (frame, etc) so it will be protected to some degree. 

Quote
I'll try one more time when I get the new mold and let it cure longer, otherwise I guess I don't have the knack for resin

Actually, most resins do have a learning curve for everyone, though there are some (which often have disadvantages for some situations) that work pretty well from the beginning or the maker just gets lucky.  Grin
There are people (and posts) here that have liked other kinds of resin too, so maybe they'll chime in as well.

** see the category on the page I linked to before called "Simulations of Resin"...and also see this page for more details on some of those other clear finishes like Varathane and Future, etc:
http://glassattic.com/polymer/finishes.htm
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)
motoredxheart
« Reply #1634 on: January 07, 2011 10:43:53 PM »

I tried searching so I'm sorry if this has already been answered...

I made some pendants with resin and when I stuck a small polymer clay charm in the charm sank straight to the bottom.
Is there a way to make sure it doesn't sink? I don't want it to go all the way down, I would like it to go right in the middle of the pendant.

Thanks!
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Diane B.
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Posts: 5074
Joined: 01-May-2004

GlassAttic --polymer clay "encyclopedia"


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« Reply #1635 on: January 08, 2011 09:14:45 AM »

The general way to add inclusions you want to stay where you put them (and not all over like glitter, etc) is to pour in a layer of resin then wait awhile for it to gel up.  Then put the item on that layer and pour more resin around it to fill up the mold. 
It's sometimes good to pre-dip the item into resin to be sure you won't trap air bubbles around the item while pouring the second layer too.

Sometimes lightweight things will rise too so may have to keep pushing them down for awhile (or if on the bottom, glue them down).
« Last Edit: January 08, 2011 09:17:07 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)
hello color!
« Reply #1636 on: January 10, 2011 09:24:29 AM »

Robin,

30-50 casts is about normal for most molds. (Obviously, molds with more detail and texture will not last as long.) Does that book talk about jewelry scale stuff at all? IMO it's so different from casting larger objects and I could use some tips, like things to use as tiny mold straps, etc...

ChantaL,

I don't think you can get a mirror finish on resin by buffing. Your best bet is either keeping the interface that resin forms with air when it's still liquid or using a very smooth mold. People have gotten good results by using plastic packaging, but the down side is that it can only be used once and most of it is too big for jewelry. I can't speak to it myself, though, since I'm quite a fan of the matte finish.

Amalia,

You can get hexagonal coaster molds that are made especially for resin here. I don't remember if they're polyethylene or polypropylene, but they'll definitely release. You should still use mold release with them, though, since all molds stick to some degree.
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amaliadc
« Reply #1637 on: January 16, 2011 08:39:47 AM »

So I finally had the chance to start over with my coasters - the mold was definitely the issue! Even just in the mold I could tell the difference - no bubbles, or any other issues. Granted they're still in the mold, I'm letting them cure a lot longer than I did last time - however, you can already tell it's going to come out great.

I used hexagon coaster molds (they come 4 coasters in a mold) with glass inserts - I covered the inserts in resin so you won't really see them.

So, just an fyi to everyone, don't use black molds that are made for cement or mosaics, they were awful Smiley

I'll post pics of the finished product if anyone is interested....
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amaliadc
« Reply #1638 on: January 18, 2011 09:24:05 AM »

I have a random follow up question....I went to Michael's and bought Castin Craft polyester resin with catalyst - having no idea there was an epoxy type. I know polyester is fairly toxic, I kept the windows open with a fan with an OSHA mask on while working with it, but I'm sure I inhaled a ton of fumes. I only worked with it on two separate days - that was it and now that I know about epoxy I threw out the polyester and bought epoxy to work with.

I only got a slight headache from it, but I'm kind of concerned about the long term effects. Should I be worried about my exposure, even though it was short-term?


Also, here's a pic of the coasters I made! Smiley

http://i7.photobucket.com/albums/y282/ImAmaliaBedelia/photo-1.jpg
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illuminatingone
« Reply #1639 on: February 19, 2011 04:17:12 AM »

Hobby Lobby has a lot of candy molds that you might could use!
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