Epoxy verses Polyester

[bruce119]

Epoxy verses Polyester

I have been struggling for the last month or so doing castings. I read so much my eyes hurt and my head burns (that mite be the fumes).

I have casted a variety of things from clear to pine cones. Some success a lot of failures. I have discovered it's not as easy as it sounds. It doesn't work the same every time.

I started with epoxy resin MAX CLR-HP from Polymer products. It performs well, the customer service isn't all that great, epoxy is expensive. He said I could thin it out with acetone but that was a failure it never harden and stayed flexible. I added about 25% acetone.

I tried polyester I got from a craft store casten'craft casting resin. It worked OK though it was a little hard to work with like turning glass. Very brittle that brings us to the next part.

Currently I just got a gal. of silmar 41 from US Composites. The price is rite I can buy 3 of these for the price of 1 epoxy.

First the specs. I am casting in a mold I made from a cutting board inside diameter is 1x1x6. I have 2 molds I am using a pressure pot. I use about 50lbs pressure. I am trying a variety of things impregnating porous palm wood, pine cones, loofha and what ever else I can put in the mold. My shop is A.C. about 78 -80 deg.

My likes and dislikes. I like epoxy it seems to be more reliable. It turns easier. It doesn't eat rite though a plastic cup. It's expensive a BIG factor.

Polyester I like the price. I am trying to get the hang of it but struggling. I used 3-4 drops per once as others say. I mix about 6 oz. each mold takes about 3-4 oz. It sat all night in the pot still not cured. Put it out side to air (I'm in Florida) for a few hours still a little runny. We're about 16-18 hrs now so I put it in the toaster oven about 150 for 1 hour just getting dry.

I know I heard a little sticky is normal but I must be doing something wrong. I read too much catalyst will make it brittle. But It would be nice if it were to cure in say about 6 hrs or so.

Any more suggestions I will keep experimenting but that get expensive. I like the epoxy but I want to try to make the polyester work. And what do you guys mix the poly in plastic cups don't work. I found that out the hard way. What a mess resin all over me the floor a disaster.

Well enough said for now if any body can think of any thing that mite help me PLEASE.

Thanks
Bruce, Florida

 

[gketell]

What did you have in the resin? Straight clear resin with 3-4 drops will harden in a few hours. Same resin but add a dozen drops of black liquid TransTint dye to the resin and with 10 drops it takes a day or so to harden. I've read for someone making a "gold" resin that takes weeks to cure.

GK

 

[Glass Scratcher]

How fresh is your MEK hardener for the PR or Silmar?

 

[neon007]

OK. First let me clear up a few things. If you are going to use PR then I suggest getting it from Mr fiberglass or US Composites. PR does have a shelf life. either 30 or 90 days. Cant remember witch one. I think 90 days. Sometimes old resin works and sometimes it doesn't. I have had exp. with both. Next as far as catalyst goes, the amount you use doesn't make it any harder to turn or shatter. It just effects the chemical reaction. I don't know what 3-4 drops per ounce comes out to, but the proper amount of catalyst is 1-2%. For me I go real hot. In 8oz. of PR I use 7.5cc of catalyst. Any more and you risk it cracking. Any less and you never know when it will harden. For me anyway. I know that alot of guys have great success with 3-4-drops per ounce, but I don't seem to. Give my way a try once. It may work for you. Takes me about 30min. and I'm cutting and turning. Hope this helps. Good luck and keep us posted.

 

[bruce119]

Thanks for some of the tips. ALL the stuff I have is brand new. Nothing added I'm still going to try and get the silmar 41 from US Composites to work for me. But I do like the epoxy I think it is more reliable and easyer to turn but 3 xs the price. I will spend a few more days researching and keep chugging away.

bruce

 

[gketell]

Alumilite is much less than 3x the cost and works well using a 1:1 mixing ratio. It is a Urethane Resin.

GK

 

[Tubby]

Bruce,

Some other things to think about before you give up on the Poly Resin. Humidity DOES play a factor in the curing or hardening of the resin. I live in Wichita Falls, TX and when it was raining every day for 2 months I had to adjust my hardener to account for that. Usually it is hot and dry here and 3-4 drops per oz was fine. Try 6-8 drops on the next pour and see what happens. I have gone as high as 14 drops per ounce, but did not like the way it turned.

Are you casting under pressure? If not you may want to look into it. Not going into it here, too much has been researched and posted to cover.

Keep us posted on your efforts, and more importantly your results []


Ed Jordan
Wichita Falls, TX

 

[bruce119]

Thanks Ed Here in FL this time of year it's like a rain forest. But I do have the air on in the shop as mentioned in original post. But may be it's affecting it some how. And I do cast using pressure as mentioned and the compressor draws it's air from the shop not out side or I would think once you pressurize the tank what goes in is what you got and air would not be a factor only temperature and the tank sits on the bench in the shop.

Greg I heard a lot about Alumilte I mite try it next time. How does it turn is it easy/softer like epoxy or hard like poly. How is the penetrating properties. Could you use it to impregnate say a soft spongy wood or a pine cone something like that. How long does it take to cure. What is the viscosity like and pot life. How hot is it (chemically) does it eat through plastic cups.

Thanks for the input. I like the epoxy it turns real nice. I will keep trying to get the poly to work. I will try the alumilte next time out of bucks rite now. so I'm stuck With what I got.

Thanks
Bruce

 

[gketell]

Bruce,

Caveat reader: I have yet to use alumilite but I've read a bunch from people who do and I've seen their results as pens.

It turns great. I don't know about hardness, no one ever mentioned it.

It penetrates beautifully. Take a look at http://www.penturners.org/forum/photo_album.asp?mode=search&AlbumUsers=0&Photo_Search=cactus&submit1=search and know that Mesquiteman uses alumilite exclusively to make his cactus blanks.

Cure time: That is one of Alumilites main draws if you are making a bunch of blanks. It sets in 3-5 minutes and is unmoldable in 10. Look at http://www.alumilite.com/checkout/movie.php to see the entire process. The other of Alumilites main draws is that it doesn't smell!

No, it doesn't eat through plastic.

It pours like water.

Not sure about the pot life.

GK

 

[bruce119]

I will try some alumilte when I get paid. Sounds like you got to work fast. Sets in 3-5 minutes doesn't sound like much time to soak in for deep penetration. But if it's like water I guess it soak in fast. I will read up on it.

Thanks Greg for being there and willing to answer questions. I do a lot of research and try to work things out myself before I ask.

Thanks again Greg a lot of others benefit from your answers also.

Oh bye the way I'm just about to make another cast. I'm going to use the silmer and pump up the catalyst it says 1% that's about 3ml so that is what I'll do. We'll see. I'll let you know and I'm casting a pinecone & loofah

Thanks
Bruce

 

[gketell]

3-5 minutes does *sound* fast. Here's the deal. When you do your cast today start a stop watch just as you add the catalyst and stop it once your blanks are setting. Based on other's work and what they have said, it doesn't require you to rush at all.

GK
ps Let us know your timing results.

 

[MesquiteMan]

As Greg said, I use Alumilite exclusively and have used over 35 gallons of it so far. Needless to say, I have quite a bit of experience with it!

Alumilite is a 1:1 urethane resin made specifically for casting. It is truly water clear and has virtually no odor. It is not considered hazardous like PR. Here are some of the technical properties of Alumilite Clear:

Cured Properties:
Hardness, (ASTM D-2240) Shore D 80
Specific Gravity (gm/cc) Density 1.04
Cu. in. per pound 26.7
Color Colorless/Clear
Tensile Strength (psi) 4,700
Elongation (%) at yield 7-10
Flexural Strength (psi) 7,500
Flex Modulus, x 10/5, (psi) 2.0-2.5 (200,000-250,000)
Izod Impact, (ft.-lb./in.) 1.0
Compressive Strength (psi) 8,350
Compressive Modulus, x 10/5, psi 3.5
Shrinkage (in/in) Maximum .005

The most important parts above to us penturners is the hardness and the Elongation at yield. Hardness is just that, how hard it is. Elongation at yield is how much the material will stretch before it breaks. The way I understand it, it can also be an indicator as to how brittle a material is.

Alumilite is actually harder than PR at a Shore D of 80 (pr is usually around 75-78)but its elongation is better at 7-10% (vs. 3-4% for PR).

As far as turning it, I think it is wonderful. It has no smell when drilling or turning, and you DO NOT have to worry about sanding or rounding the edges before turning like some do with PR blanks. I have tried to make an Alumilite blank blow up and have not been able to so far. I have started with a square blank and jabbed a dull gouge in very aggressively and have not had one explode. If you drop a blank on the concrete floor, it will not crack or break.

I will have to respectfully disagree with Greg on the set time issue. It is not a problem at all in my experience. I mix and pour 19 ounces at a time and have never had an issue with the resin going off before I get it pressurized in the pot. The 4.5 minutes really does not start until you have it mixed. If you are adding color, you always add the color to part A and completely mix before adding part B so that is not an issue either.

As for penetration, like Greg said, it penetrates very nicely. I use it for my Worthless Woodâ"¢ blanks (http://builtbydoc.com/penturning_resources.htm)and get penetration into most of the smallest cracks. It does a fair job at penetrating punky wood but I would not expect too much from it in that department.

The drawbacks to Alumilite are few but as with anything superior, there are some! For one, the cost of Alumilite is more than PR. A 1 gallon set of Alumilite is $160 plus shipping. Their 1 gallon set is 1 gallon of each part. This makes 2 gallons of mixed resin so the price is $80 per gallon. If you buy in 5 gallon sets (10 gallons mixed resin) then the price drops to around $55 per gallon. IMO, the lack of wasted resin due to issues like you are having now more than makes up for the cost difference.

The other complaint with Alumilite is that some can not get as high of a gloss with the blanks as they can with PR. I get a nice shine with mine but it is not quite as glossy as a CA finish on wood but is still very nice. If I need a super shine for some reason, I simply do a CA finish over the blanks.

Sorry this has been so long but I hope it helped some! If you seriously want to try Alumilite, shoot me a PM and I will let you know who to contact to possibly get a free sample.

And just for the record, I have no ties whatsoever to Alumilite. I do not get any commissions and I do not work for the company in any way. I am just a very happy customer!

 

[gketell]

Curtis, you misread my post. I wasn't saying it was too long. I was actually saying it ISN'T too fast, it just sounds that way. "it does *sound* fast .... you don't have to rush at all". Again, having never done it, my comments were all from reading about Alumilite (mostly from you).

You were just used to me being spooked by the speed. But you've convinced me. []

GK

 

[bruce119]

Success.....2hrs later we have a cast!

They popped rite out just a little sticky on the sides like others said. But they look OK like there going to work. I'll know later on tonight or tomorrow when I turn them.
just wanted to let you guys know.

Thanks for the help.
Bruce

I wrote this before I saw the other posts. Curtis thank you for responding. I will shot you a PM a little later. I'm a little busy rite now. And it took me about 2-3 minutes form start to finish. The first drop of catalyst, mix, pore, in the pot & add pressure.

Thanks again
Bruce

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<br />

 

[MesquiteMan]

Originally posted by gketell
<br />Cure time: That is one of Alumilites main draws if you are making a bunch of blanks. It sets in 3-5 minutes and is unmoldable in 10. Look at http://www.alumilite.com/checkout/movie.php to see the entire process. The other of Alumilites main draws is that it doesn't smell!

Greg,

I actually was responding to the message above! I had typed my reply before your posted the follow up!

 

[gketell]

Ahhh, OK. But I still meant that as a positive. "main draws". Oh well, I guess we're just talking past each other today.

I'm going to order some Alumilite soon. My wife can't stand the smell of the PR, either casting or turning.

GK

 

[elody21]

If I am not mistaken all epoxy will eventually yellow. Any I have tried has yellowed in about 9 months to a year. I even used white marine epoxy one time and it yellowed. Alice

 

[its_virgil]

Polyester resin has a shelf life of 90 days from the date of manufacture, not from the date of sale or the first opening of the can. The only PR I've had any problem with was purchased from Michaels and Hobby Lobby. They just don't sell if fast enough....these are my thoughts. I purchase only from resin dealers, either mrfiberglass or composites one. I use 3 drops per ounce for clear casting snake skins..coloring can alter the cure time. I think I sould get this reponse boilerplated, as should Curtis with his Alumilite comments. [][]
Do a good turn daily!
Don

 

[Fritz]

I also use Alumillite with great success. I can get a lot more done with the time I save.

John Fritz

 

[stevers]

Very good point Virgil. I bought some Castin Craft resin from my local hobby shop and it turned out to be bad. No idea how long it had been on the shelf, but it was like like heavy syrup. Real thick and sort of sticky.

 

[dbriski]

Is there a shelf life on Alumilite?

 

[MesquiteMan]

Alumilite says 6 omnths on the shelf life. I use it up too fast to know if that is accurate or not!

 

[bruce119]

Well it's the next day and good news / bad news.

Good news I got a pretty good loofah pen.

Bad news the pine cone exploded.

My feelings the poly is a little hard to turn. It seems to be a little fragile. I did the pine cone first and I find that the ploy is very hard and hard on the tools. I had a very sharp chisel and sharpen it a few times during turning. I find I have to go real slow (cutting that is the lathe is spinnig fast) or the poly will chip. Well as I was turning the pine cone it exploded. You can see the chips in other places. I am trying to be careful and cut very light.

The loofah turned pretty much the same but I got it done. Again I find the poly very hard and easy to chip in fact there is a crack or two in the pen. It did polish up very nice.

The very short experience I have with poly & epoxy is that poly seems to be harder & less forgiving. But polishes up very nice when you get it. The epoxy is easier to turn, doesn't chip & is more forgiving.

This is just my experiences I am sure they will change as I continue to work with resin.

How does alumilte compare to poly & epoxy.

Thanks for everyone's input.

<br />

<br />

 

[ElMostro]

Bruce,
Allumilite is much, much easier on your tools. It is hard but not glass hard like poly. It is easier to drill too and pretty much eliminates the possibility of the blank blowing up on you during drilling or turning. The other thing I like about Allumilite is that since it is a 1:1 mix you don't have to be checking on the alignment of the stars to decide how many drops of catalyst you need.
ahh...and it does not stink!

 

[its_virgil]

Is poly in reference to polyester resin or some other poly-something else resin? On some fancy name scientific hardness test the report is that polyester resin is not as hard as Alumilite. I've cast and turned (more than) a few polyester resin blanks and I must say that I've had no problem with them while drilling or turning. Polyester resin does not take well to a gouge but it loves the touch of a nice sharp skew[]. Ane, I never look at the stars to cast. I use three drops per ounce and it works every time, at least with my snake skins. Can't make any claims with colors or cactus or lufa or pinecones or feathers, but all of those things do sound intriguing. Now, where is that sextant...
Do a good turn daily!
Don

Originally posted by ElMostro
<br />Bruce,
Allumilite is much, much easier on your tools. It is hard but not glass hard like poly. It is easier to drill too and pretty much eliminates the possibility of the blank blowing up on you during drilling or turning. The other thing I like about Allumilite is that since it is a 1:1 mix you don't have to be checking on the alignment of the stars to decide how many drops of catalyst you need.
ahh...and it does not stink!

 

[MesquiteMan]

Don, what is that huge telescope you bought for then???[][]