what am i doing wrong with this resin?

[raser13]

i just bought the castin' crafts' easy cast clear casting epoxy from hobby lobby and i measure it out 50%-50% like the box says and no matter what i do the stuff stays sticky. i'm measuring it out by using those little graduated measuring cups that come with cough medicine bottles(btw where do you get those things in mass quantities? i can only find ones without lines.)and kinda eyeballing it at the lines. does it have to be that precise on the measurement and if so how do i get that close? if it does why on earth would they call this stuff "easy cast" i figured with a name like that there would be a little lee way. pleeeeeeeaaaaaase help i have lots of molds waiting to make clear parts once i figure this out.

[Kylwell]

IIRC, depending on temp & humidity that stuff can take up to a week to fully cure.

In other words, it's crap.

[raser13]

IIRC, depending on temp & humidity that stuff can take up to a week to fully cure.

In other words, it's crap.

darn it(boy that just don't convey the frustration) my first venture into clear parts and i get the bad stuff. i live in missouri lots of heat and a butload of humidity. all right what's the right stuff and how many arms and leg will it cost me?

[Kylwell]

You can try defaulting to more hardener but which that is I canna remember.

Casting pros? What do ya'll suggest?

[macfrank]

darn it(boy that just don't convey the frustration) my first venture into clear parts and i get the bad stuff. i live in missouri lots of heat and a butload of humidity. all right what's the right stuff and how many arms and leg will it cost me?

Clear resins are a PITA to cast properly. The heat may not be an issue, since it should help the resin set. The humidity may be an issue, but that usually just means bubbles in the resin.

What type of mold did you use? Some clear resins (like Envirotex) will not set properly in an RTV mold - at least not without some work - but will work in an OOmoo mold.

Alumilite makes a clear resin, but you need a warm (hot, actually) mold and this just makes the resin set faster, so not only will you need a place to keep the mold warm, you'll need some way of degassing the resin before and after the pour.

Frank

going up the clear resin food chain, you start getting into pretty nasty (health-wise) resins.

[raser13]

i'm looking for some thing that is glass clear. i'm planning to see rooms that
i'm building on the other side. for example i want to cast the bridge section clear so that you can see the bridge i'm building through the dome.plus many other ideas.

[Kolschey]

In my experience, humidity and temperature make a substantial difference in the curing of epoxy. If conditions are cooler than ideal, I will often use more catalyst in order to "goose" the reaction.

The brand of the epoxy, and the age of the actual chemistry are also significant factors to consider.

[Joseph Osborn]

I had nearly the same experience when I bought a small container of this particular brand of clear epoxy. My problem was not with stickiness, but instead the castings never cured hard and stayed the consistency of a pencil eraser. I have one piece here on my desk that is at least seven or eight months old and it's still as soft as it was the day after I made it. I prefer to use the 20-minute "finish" epoxy from the R/C side of the hobby shop. That stuff is rock-hard after a couple of days at room temp or a few hours at 150 in my curing oven. Only problem is that it cures with a slight yellowish tint. Since I usually tint my castings red, it's not a problem for me.

BTW, you can get the little 1-oz measuring cups at the hobby shop too-- usually stocked along side the various fiberglass resins and cloth. The last pack of 100 cups cost me $5.95. I'm sure they are available elsewhere for a better price but I haven't shopped around.

[Chacal]

i'm looking for some thing that is glass clear. i'm planning to see rooms that i'm building on the other side. for example i want to cast the bridge section clear so that you can see the bridge i'm building through the dome.plus many other ideas.

Maybe for that specific purpose it would be best to vac-form the hull. The plastic will be thinner and will give you less optical distortion (so you can actually see what's inside). It is very difficult to cast an optically flat part. With vac-forming the plastic's natural thickness (and a good, smooth master) will be almost perfect, especially if you use more 'noble' plastics such as polycarbonate.

[modelnutz]

First question... what are the molds made of ? If you used a tin cure silicone....you're fighting an alcohol that leaches out of most tin cures..( alcohol is a solvent for Epoxy ) ..solution..... use platinum cure rubber
( smooth-on's Sorta-Clear is very good )
Quick fix....( works sometimes)....heat your molds in an oven set to 180 degrees....bake for half an hour.....do a test pour of your Epoxy.
You should get a fairly decent set...faster set as well..may be slightly cloudy though.


Epoxy really likes heat...when doing composite panels, heat and pressure assure high physical properties ( it makes it stronger )

If you want to get "big boy" results....check out Poly-Tech....they have some great clear urethanes.

[Umi_Ryuzuki]

...

If you want to get "big boy" results....check out Poly-Tech....they have some great clear urethanes.

I still let my molds cure for seven days before using polyurethane
clear cast or soft polyurthane rubbers in the molds.

[USS Atlantis]

With the Castin Craft - get yourself a small toaster oven

Set the oven to 150 degrees

Put your mold with the resin pour into the oven

Walk away for 2 hours

D-mold

put the resin in the oven

Walk away for 2 hours

Take the resin out, put it on a shelf

Walk away for 24 hours


I've actually had some good luck with that resin - re-made a set of mirror clips for a friend using it

[Stu Pidasso]

i'm measuring it out by using those little graduated measuring cups that come with cough medicine bottles(btw where do you get those things in mass quantities? i can only find ones without lines.)

I get mine off ebay. I just bought 200 last week, cost me $20.00 shipped.

[raser13]

the mold material that i'm using is the cheaper stuff you get at hobby lobby. i'm not at home right now or i'd put up the name of it. it's the one that is a two part system that both parts are kind of like the concistency of silly putty to start with, one part is white and the other is yellow. youu knead the two parts together until it all turns yellow. once hardened the mold has the consistancy of a pencil eraser. hope that helps till i get home and find the name for you guys. btw i just did another set with the same resin two days ago,heating it in the oven. that set isn't stidky but it is still soft and can be bent without much effort just like joe osborn said. any sugestions? chacal , the parts that i'm casting are from a vau form kit, or were you meaning to revacuform them in clear plastic?

[raser13]

the mold material that i'm using is the cheaper stuff you get at hobby lobby. i'm not at home right now or i'd put up the name of it. it's the one that is a two part system that both parts are kind of like the concistency of silly putty to start with, one part is white and the other is yellow. youu knead the two parts together until it all turns yellow. once hardened the mold has the consistancy of a pencil eraser. hope that helps till i get home and find the name for you guys. btw i just did another set with the same resin two days ago,heating it in the oven. that set isn't stidky but it is still soft and can be bent without much effort just like joe osborn said. any sugestions? chacal , the parts that i'm casting are from a vau form kit, or were you meaning to revacuform them in clear plastic?

[raser13]

the mold making material is called "Amazing mold putty"

[Stu Pidasso]

the mold making material is called "Amazing mold putty"

I have some of that. It sucks.