Epoxy resin question

[VotTak]

Does anyone uses epoxy resin? Which brand? If you use it to cast worthless wood - is it better or worse than alumilite? I was searching forum but did not find anything.

 

[Indiana_Parrothead]

I us the West Systems epoxy. The 105 resin and the 207 hardener. I have not cast any worthless wood, but have cast gumballs, flower petals, ferns, etc. I think one advantage is that alumilite does not play well with any kind of moisture where epoxy is a lot more forgiving in that area. Also you do have a lot longer open pot time once mixed to work with it.

Mike

Correction, it is the 105 resin I use, too early in the morning yet.

 

[ladycop322]

What Indiana Parrothead said except I use West Epoxy 105 and 207. Not sure what the difference is but that is what I use. I cast watch parts, labels and decals. Not familiar with worthless wood though.

 

[ladycop322]

Here is a link to a comparison chart using West products

WEST SYSTEM | Products | Product Selection Chart

 

[VotTak]

Can I use Alumilite dyes with epoxy? Mica powder? How about bubbles? Do you use pressure or vacuum to remove them?

 

[ladycop322]

Difference between 205 and 207 is 205 is a fast hardener and 207 is a special clear hardener. Personally, I like the slower hardener as it gives me more time to dye resin for special custom blanks. Good luck.

 

[VotTak]

Michelle, thanks for your input.
As I mentioned before, how do you remove bubbles?

 

[Charlie69]

how do you remove bubbles?

I have no experience casting pen blanks with epoxy but I use epoxy with frp or composites and degas (remove bubbles) epoxy using vacuum. Degassing the resin is critical with high performance composites because a void free laminate or layup is much stronger than a laminate with bubbles in it. That being said I don't see why pressure wouldn't work also.

Honestly the best way to remove bubbles ime is not to introduce them in the 1st place. Lots of ways to reduce bubbles with epoxy... some of which are common in the casting world.... like warming the resin before mixing, preheating the mold, pour the epoxy into the mold at an angle (think beer). You can even buy specialized epoxy resin mixers that will combine the resin and hardener without introducing bubbles.

I was wondering how much the West System 105/207 yellows after 6 or so months? Are you guys and gals seeing significant yellowing on the cast blanks? Or are you only casting with epoxy over darker backgrounds like carbon fiber? I realize the 207 has UV inhibitors but those blockers have limited effectiveness and most people in the composites world use a clear coat like a 2k urethane that has serious uv blockers over the epoxy laminated part to minimize the chalking and yellowing. I realize we're talking about pens here and not car hoods and panels but I can't help but wonder what an epoxy cast blank looks like after a few months.

Anyways... I'm a huge fan of epoxy. If I ever get into casting blanks it will be with epoxy. It's relatively harmless especially compared to polyester and styrene and easy to use once you know a little bit about it. Moisture isn't a big deal with it and it takes most pigments and dyes. I've even colored it with powdered kool aid mixed with xylene. Given the right formulations time isn't an issue with the stuff so 7,8,9,10 -100 color pours wouldn't be a problem,,,,the skies the limit.

hope this helps

 

[SteveG]

Michelle, I am also wondering what is your response to VotTak, post #7. I live on a small island where it is difficult to get PR (no local hobby supply, and regular "hazardous shipping" is prohibitive due to location, etc.). The moderate to high humidity makes Alumilite a challenge, since the stuff goes bad just sitting in the bottle in the humid environment.)

All that said, I am thinking that your epoxy approach might be my answer. Thanks if you have any suggestions.

 

[Skie_M]

Removing bubbles ......


Use heat to make the epoxy mix much more liquid, allowing the bubbles to rise out of the mold ... preheating the mold helps as does pouring the epoxy in a manner that reduces the air trapped in the mold.

Use vibration to help make the bubbles rise ... set your filled mold on a vibrating tumbler or some other vibrating tool to help clear the bubbles out of your mix before it sets.

Use negative air pressure to make the bubbles bigger, which will help them rise out of the mix ... This is a vacuum setup. You can combine this with other efforts to help move those bubbles out of your mix before it sets.

Use a push stick ... visible bubbles can be removed manually by taking a thin stirrer or other item to reach into the poured mix before it sets and pushing bubbles away from the items cast within. Generally a last resort, as it can leave "tracks" through the clear resins or introduce other contaminants.

Use overpressure ... By using a pressure pot and higher atmospheric pressure, you DO NOT REMOVE any bubbles from the mix, but since air pressurizes and shrinks more than liquids, the bubbles trapped in the mix can get very small and pretty much unnoticeable. As I said, it won't remove any bubbles, it just makes them smaller. If there are a lot of them, they can appear as a haze floating in the finished casting... This method is much more prevalent in castings that have a more opaque look to them.

 

[BRobbins629]

Removing bubbles ......

Use overpressure ... By using a pressure pot and higher atmospheric pressure, you DO NOT REMOVE any bubbles from the mix, but since air pressurizes and shrinks more than liquids, the bubbles trapped in the mix can get very small and pretty much unnoticeable. As I said, it won't remove any bubbles, it just makes them smaller. If there are a lot of them, they can appear as a haze floating in the finished casting... This method is much more prevalent in castings that have a more opaque look to them.

Pressure does not shrink the bubbles, none the less it does reduce them. Rather it makes the air that causes bubbles go into solution similar to a soda bottle. On the shelf, there are no bubbles in soda due to the pressure in the bottle. Remove the cap, release the pressure and bubbles appear. A simple calculation using the gas pressure law where pressure and volume are inversely proportional will tell you that at the pressure we use to cast, the volume of a bubble couldn't really change that much. A 2x increase in pressure only decreases volume by 1/2. Since the volume of a shere is proportional to the cube of the radius, you wouldn't see much of a change. Still works, just wrong theory.

 

[Indiana_Parrothead]

Michelle, I am also wondering what is your response to VotTak, post #7. I live on a small island where it is difficult to get PR (no local hobby supply, and regular "hazardous shipping" is prohibitive due to location, etc.). The moderate to high humidity makes Alumilite a challenge, since the stuff goes bad just sitting in the bottle in the humid environment.)

All that said, I am thinking that your epoxy approach might be my answer. Thanks if you have any suggestions.

Steve, I have used epoxy for about two years now and not have any problems with epoxy setting up in high humidity. Actually it setup better in summer because of the heat. In July/August we have anywhere from 80-90%. And I have had some cans up to 6 months without them going bad. The last cans I bought were shipped through USPS and the take nothing hazardous so you should be good.

Mike

 

[Indiana_Parrothead]

Removing bubbles ......


Use heat to make the epoxy mix much more liquid, allowing the bubbles to rise out of the mold ... preheating the mold helps as does pouring the epoxy in a manner that reduces the air trapped in the mold.

Use vibration to help make the bubbles rise ... set your filled mold on a vibrating tumbler or some other vibrating tool to help clear the bubbles out of your mix before it sets.

Use negative air pressure to make the bubbles bigger, which will help them rise out of the mix ... This is a vacuum setup. You can combine this with other efforts to help move those bubbles out of your mix before it sets.

Use a push stick ... visible bubbles can be removed manually by taking a thin stirrer or other item to reach into the poured mix before it sets and pushing bubbles away from the items cast within. Generally a last resort, as it can leave "tracks" through the clear resins or introduce other contaminants.

Use overpressure ... By using a pressure pot and higher atmospheric pressure, you DO NOT REMOVE any bubbles from the mix, but since air pressurizes and shrinks more than liquids, the bubbles trapped in the mix can get very small and pretty much unnoticeable. As I said, it won't remove any bubbles, it just makes them smaller. If there are a lot of them, they can appear as a haze floating in the finished casting... This method is much more prevalent in castings that have a more opaque look to them.

I have used epoxy for two years new and you really don't have to do all that to get bubble free castings. I do have a pressure pot now but even before I did about the only thing I did was to slightly warm the resin and hardener. Because of the time it takes to setup the bubbles work out on their own. The vibration and vacuum is just overkill.

Mike

 

[Skie_M]

Whoa there, I never said you HAVE to do all of that to remove the bubbles .... just do whatever works for you!

 

[ladycop322]

It seems that everyone likes to make extra work for themselves. I have never used heat I've never had to worry about the temperature in my workshop when I cast with epoxy resin. I simply gently mix the two together Epoxy and Hardner. pour it into the mold and place in the pressure pot at 50 PSI for about 8 to 9 hours. When I remove it from the molds I do not have any air bubbles. No need for heating or vibration whatsoever. West marine epoxy and hardener products.

 

[jttheclockman]

It seems that everyone likes to make extra work for themselves. I have never used heat I've never had to worry about the temperature in my workshop when I cast with epoxy resin. I simply gently mix the two together Epoxy and Hardner. pour it into the mold and place in the pressure pot at 50 PSI for about 8 to 9 hours. When I remove it from the molds I do not have any air bubbles. No need for heating or vibration whatsoever. West marine epoxy and hardener products.

Just to follow up on a question that got asked about yellowing. I use epoxy resin when I am adding color or inlace so yellowing has no effect. But have you followed any of your clear casting blanks to see if this is a case. You may have not been doing it long enough, I do not know. But it maybe a good idea to have a test blank and put it through some UV light and other riggors. Maybe as the OP mentioned the use of dark background may not show any difference either. But interesting.

 

[MesquiteMan]

West System epoxy, as with most other epoxies will yellow over time. I know this first hand. I have done a lot of work with West System as well as System 3 epoxies filling voids in Mesquite for flat work and have also cast it for pen blanks. My front doors on my house are all mesquite and they both have a large crack that runs all the way through that was filled with clear West System epoxy and it has yellowed a bunch. I have a solid, clear epoxy test blank in my shop and it has yellowed quite a bit as well.

That said, once the pen is turned, the thickness of the epoxy is thin enough that you will not see the yellowing in most cases.

 

[jttheclockman]

West System epoxy, as with most other epoxies will yellow over time. I know this first hand. I have done a lot of work with West System as well as System 3 epoxies filling voids in Mesquite for flat work and have also cast it for pen blanks. My front doors on my house are all mesquite and they both have a large crack that runs all the way through that was filled with clear West System epoxy and it has yellowed a bunch. I have a solid, clear epoxy test blank in my shop and it has yellowed quite a bit as well.

That said, once the pen is turned, the thickness of the epoxy is thin enough that you will not see the yellowing in most cases.

Thanks Curtis. I kinda of thought so but have not used it as a clear resin. As I said i have always mixed with something and it will never show. Not sure what the effects would be on a watch part pen as being used. The dark background may mute the yellowing color but then the parts may take on a different hue. That is why I asked Michelle if she has knowledge on this or at least set up a test blank. Good info. I definitely know System 3 yellows because that is my go to epoxy and use it all the time but never for casting.

 

[MesquiteMan]

Here is an interesting short article from the "Epoxy Guru" about yellowing in epoxy. Problems with any Clear Epoxy Resin yellowing and more 603.435.7199

 

[spitfire]

So does adding pigments or pearlex powders cover up the yellowing? In other words if I'm coloring the epoxy resin is there any need to worry about yellowing?

 

[jttheclockman]

So does adding pigments or pearlex powders cover up the yellowing? In other words if I'm coloring the epoxy resin is there any need to worry about yellowing?

If you are coloring it no matter then.

 

[KenV]

John, it takes a lot of UV to develop yellow in epoxy. If you leave a pen sitting on the dash in the sun for an extended period of time, it will slowly develop a yellow tint. Clear PR left in the sun for an extended period of time develops discoloration.

I have some West systems cast spruce cone pens from several years ago that look the same now as then. One has spent a lot of time in pockets.

Ultra Violet also causes colors to fade, especially those colored with food colors or rit dye.

UV also does bad things to most of the things we use as finishes.


The good news is that most pens are not in a UV rich environment most of the time.

 

[Charlie69]

Ken I respectfully disagree with your assertion that "it takes a lot of UV to develop yellow in epoxy. All amine cured bisphenol A diglycidyl ether (epoxy) will yellow by itself... no exposure to UV needed. Uv exposure accelerates and exaggerates the yellowing but the epoxy will yellow without exposure to UV. Amine cured epoxy constitutes the overwhelming majority of epoxies that are available to the general public but there are other epoxies like Bisphenol f cured with cycloaliphatic amines that are less prone to yellowing. Anyhydride cured Bis A is pretty good too but the Anhydride curative requires 2 hrs@ 300F to cure the Bis A...the high temp ultimately gives the Bis A a nice amber tint so....it doesn't yellow in the typical sense of epoxy yellowing but it still appears yellow/amber.

As Curtis mentioned earlier, the walls are so thin on a cast pen blank that the yellowing may have an unnoticeable effect on the pen. An epoxy with a low color hardener and a mcu clear coat to block UV might make a nice blank.

 

[MesquiteMan]

The clear epoxy pen blank size test piece that I have has never been out of my shop and my shop has no windows, yet it still yellowed pretty badly.

 

[its_virgil]

Thanks Bruce. I've posted this same information before and well, let's just say it wasn't well received by some. But you are correct, a volume decrease by 1/2 only changes the radius, or the size, of the bubble by about 81% or so if I remember the calculations I did. Pressure keeps air i in solution and bubbles that are there are driven back into solution.
Do a good turn daily!
Don

Pressure does not shrink the bubbles, none the less it does reduce them. Rather it makes the air that causes bubbles go into solution similar to a soda bottle. On the shelf, there are no bubbles in soda due to the pressure in the bottle. Remove the cap, release the pressure and bubbles appear. A simple calculation using the gas pressure law where pressure and volume are inversely proportional will tell you that at the pressure we use to cast, the volume of a bubble couldn't really change that much. A 2x increase in pressure only decreases volume by 1/2. Since the volume of a shere is proportional to the cube of the radius, you wouldn't see much of a change. Still works, just wrong theory.