Adventures with Polyester Resin (PR)

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Here's a quick pic of one of your camouflage blanks Ken:biggrin::biggrin:
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Thanks for that! I like the fat lower part you put on the slimlines. It sort of shouldn't work, but it does!! I wish you could put a fat top half, too, but I know from experience that if you do, the clip doesn't fit.

I must try making custom clips next...
 
Two more stunning pens tunred by a customer of my blanks.
Now, I hasten to add, that the same (very experienced) turner smashed two identical blanks while drilling, so there are mixed results with these crush-type PRs.
 
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Hi Ken,
Thank you so much for this post on how you made your negatives and positives for your pen blanks.

I have made two negatives out of MDF (3/4" or 19.049999999979427mm:wink:).

They are ready for me to put either silicon in or I'm thinking about getting some Mold Max 40 (http://www.theengineerguy.com/cgi/commerce.cgi?search=action&category=BDF0).

Will I need to spray the MDF with mold release or put any type of finish on it? Or can I just put the silicon/Mold Max in on top of the raw MDF?

Thanks so much.

Chip
 
Yeah. The old metric/imperial measurements thing. It's interesting to think that the ex-pats took imperial with them and held on to it while Europe moved forward. I learned metres and grams when I was in school and only started to learn the imperial system (feet and hands and gallons) when I started to work in the (massively American dominated) aviation industry!

I've never used Mold Max 40. (Can anyone else help out here?) I may have used the exact same stuff under a different name for all I know! One thing I'm certain of: bathroom sealer is a whole lot cheaper!! (About 1/5th the price!!)

So, I'm not sure of he properties of the Mold Max, but a tip I learned after I did my step-by-step guide was that if you cover the MDF in cling film (that might be a trade name - you kow the plastic you wrap up your sandwiches in?) then the silicon doesn't stick to it and your mould is much more smooth.

I've never used mould relase agent, but MDF is certainly quite absorbent.

Hope this helps.
 
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Padre

I've been down to The Engineer Guy's store. Nice folks.
Told me that silicone won't stick to stuff so you don't need a mold release.
I gave a demo at our group meeting on Saturday on how to make molds using Mold Max 40 (green). Or you can use Mold Max 30 (pink). The 30 is a little more supple when cured. Both mix and work the same.
TEG was right, you don't NEED a mold release but it sure makes things a lot easier.
I used liquid Crisco vegetable oil. Silicone separated really easy.
However, once you have the mold made you don't need a release to get the blanks out.

Lee
 
I made the mold with your design, but made it out of 3/4" poplar, and the silicon stuck and would not release. Is there a reason you used MDR? I used GE II and I had to dig the stuff out. FRANK
 
When I worked for a company that made fiberglass boats, we just used regular paste wax like simonize or turtle. The mold was completely waxed and then painted with gelcoat. Once the gelcoat was cured we applied the chopped glass and woven matt and wood fillers and pr resin. After about 8 hours of build up we let it set overnight. We came in the next morning and popped the hull out of the mold and it was as shiny as a new car when it came out.
 
MrWright said:
I made the mold with your design, but made it out of 3/4" poplar, and the silicon stuck and would not release. Is there a reason you used MDR? I used GE II and I had to dig the stuff out. FRANK
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Oh, dear. Sorry to hear that.

Ummm... The only reason I used MDF is because that's what I had lying around. I daresay if I'd used white pine, it would probably have stuck, too. Some folk cover the mould positive with plastic sandwich wrap film.

Looks like I just got lucky with my choice of scrap wood.

If I was doing it again, I probably wouldn't bother with the wooden mold at all. A trick mentioned here is to massage a blob of silicone in a basin of soapy water unti it starts to go firm, then press a pen blank into it. The soapy water stops you sticking to the silicone and once it's cured you have a blank which is nearly the right shape.
 
MrWright said:
I made the mold with your design, but made it out of 3/4" poplar, and the silicon stuck and would not release. Is there a reason you used MDR? I used GE II and I had to dig the stuff out. FRANK
Click to expand...

I have found that a light coating of normal cooking oil (vegetable oil/canola oil/whatever you use in the kitchen) on the surface before you make a mold works great as a release agent for most mold material. If that doesn't work, you can always wrap your mold negative components in Saran Wrap and your silicone should not stick to that either.
 
quote=MrWright;1090893]you can always wrap your mold negative components in Saran Wrap and your silicone should not stick to that either.[/quote]

Brands may vary, but silicone will stick to the plastic wrap. I have a mold that I actually have used several times and teh plastic wrap is still stuck to it - yes, inside the cavity. Still works though.

In my second mold I used a couple good heavy coats of furniture paste wax (minwax brand). Worked great.
 
I covered my mold positive with clear packing tape. Works just like plastic wrap but easier to use and I can reuse it.
 
KDM said:
...and, I thought I should post a YouTube video of the blanks as I rotate them so you can see all round.
Click to expand...

...and I just found BBcode! So here's the video embedded.

[yt]IFAiv0gUBIA[/yt]

KDM said:
The first is the peachy skintone pieces remoulded in black resin.
The second is a red and blue swooshy thing of various shades. Looks like marble. Probably because I coloured it with enamel paint and it mixed in a strange way.
The third is the rainbow slivers moulded diagonally in black PR.
The fourth is the grey and mint green PR blanks I smashed up with a hammer. The pieces have been set in black PR.

I'm looking for names for each of these blanks. Does anyone have any suggestions?
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I love it.. I used the same materials as you... one question for you..

did you notice when you polished the pen you had tiny white spots.. ie very very tiny bubbles.

I had a couple .. they sparkled but I thought it was just due to trying to cure the resin when it was -11 degrees here... but your black and red looks just like mine!!! well done.

I cant wait to try out various other pigments.. there are also some translucent ones which i am eager to get..
 
Didn't notice any white spots and didn't notice any bubbles.

I've found the best way to get rid of bubbles is to let the resin sit inteh mixing cup for a few minutes before you rpour it into the mould. When you pour it, pour slowly.

Now that you mention the temperature, I have noticed that my clear resin has started to set quite cloudy. At first I assumed my supplier had changed source, but he assures me he's always sold me a product called "PolyLite" and it's the same stuff I've been buying since the summer. So, yeah, your white spots could well be temperature related. could set perfectly clear during our 18 degree summer, but now that it's -4 at night, my blanks are setting cloudy and they come out really sticky.

One good thing - they appear to be less brittle. Maybe it's my imagination. Maybe a slow cure isn't so bad!

If you source those translucent pigments in the UK, give me a shout. I'd like some of that action!

I have anther couple of threads on PR. Here (mica pigments and PR segments) and here (casting coffee beans). One of the black and reds you mentioned got made into a pen here.
 
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I tried doing some casting with the resin that Michaels sells. It has been 2 days in the garage (unheated) you guys in Virginia know how cold it has been out and it is still like jello. I have it in a 8 oz tupperware container. Maybe I should bring it in the house?
 
Ooooh. Did you catalyse it? The mixing in of teh MEKP catalyst should have caused it to warm up sufficiently to start the curing reaction.

Not sure if I would bring it in the house - just because of the smell (and the vapour probably isn't good for you anyway!!) But I would definitely try and warm it up a bit. Some folk say 5 minutes in a 120 degree C oven....
 
navycop said:
I tried doing some casting with the resin that Michaels sells. It has been 2 days in the garage (unheated) you guys in Virginia know how cold it has been out and it is still like jello. I have it in a 8 oz tupperware container. Maybe I should bring it in the house?
Click to expand...

You need to get it in an environment that the ambient temp is about 80 for about 4 hours that will get your resin to set. If you heat it too much over 150 it will go more brittle. Even at 80 for 4 hrs it still may be tacky on the surface that is OK. The resin will never set with ambient temp below 65 deg. You would have to load it up with MEKP to get it to set then it will be brittle as glass. 3-4 drops per once ambient temp no less than 72 and patience I give it 12 hrs then put them in the warm sun to finish that usually takes care of the tackiness. Though here in Florida the sun has not been warm and I had to use an oven set at about 80-90.

Bruce
 
You have risen as of lately to be the guru of the castings. I have a question though, are you using vacuum or pressure to make your castings? I may be missing it in all the posts or it is assumed that one is already using omitting the detail. I am considering the pr bug as I have a few college color pens I have been requested to make. I also intend on casting some fly patterns in clear for some fly fisher buddies. What are your thoughts on this?
 
Heh heh! Very kind of you to say so. Not entirely true, though. I'm re-learnig what a good few folk on here alredy know. Re-inventing the wheel in many cases. Ah, what the heck. I've always thought the circle was a stupid shape for a wheel, anyway.

I hope I am able to pass on SOMETHING - it's purely self-taught and from tips I've picked up around here!!

I've never used vacuum/pressure. But, to be honest, there's a vagueness surrounding the word "casting." Yes, I suppose, if one starts with a liquid material, sticks it in a mould and ends up with a solid, it would, strictly speaking, be "casting." I think most folk would call casting the process of embedding some foreign object in their PR. To be honest, if I were casting objects into PR regularly, I would probably use a pressure pot.

No, my process for casting objects involes a thin coat of un-catalysed PR. Let this soak in for a day or so before dropping the object into the catalysed PR. That allows most of the bubbles to escape.

For me, the hardest part is "swirl." Getting the timing right just before it goes to gel is really trial and error and luck and flaw!!

Definitely try it. It's spectacularly rewarding.
 
Make yourself a hotbox

navycop said:
I tried doing some casting with the resin that Michaels sells. It has been 2 days in the garage (unheated) you guys in Virginia know how cold it has been out and it is still like jello. I have it in a 8 oz tupperware container. Maybe I should bring it in the house?
Click to expand...

A few months back I made a hotbox from scrap materials and I use if for a lot of things

drying painted tubes
heating PR
drying wood blanks
post-cure of PR
etc.

here is my OP on making it
http://www.penturners.org/forum/showthread.php?t=58870
I have five molds in it right now. 150 deg with 1 60 watt and 1 75 watt light bulb.
 
ribanett said:
navycop said:
I tried doing some casting with the resin that Michaels sells. It has been 2 days in the garage (unheated) you guys in Virginia know how cold it has been out and it is still like jello. I have it in a 8 oz tupperware container. Maybe I should bring it in the house?
Click to expand...

A few months back I made a hotbox from scrap materials and I use if for a lot of things

drying painted tubes
heating PR
drying wood blanks
post-cure of PR
etc.

here is my OP on making it
http://www.penturners.org/forum/showthread.php?t=58870
I have five molds in it right now. 150 deg with 1 60 watt and 1 75 watt light bulb.
Click to expand...

Three two part questions:
1. How long do you leave the lights on (overnight, couple hrs)?
2. What kind of vent is on the top? Just a hole with a loose piece of cardboard.
3. Will any cardboad do (display boards, dishwasher box, etc)?
 
navycop said:
ribanett said:
navycop said:
I tried doing some casting with the resin that Michaels sells. It has been 2 days in the garage (unheated) you guys in Virginia know how cold it has been out and it is still like jello. I have it in a 8 oz tupperware container. Maybe I should bring it in the house?
Click to expand...

A few months back I made a hotbox from scrap materials and I use if for a lot of things

drying painted tubes
heating PR
drying wood blanks
post-cure of PR
etc.

here is my OP on making it
http://www.penturners.org/forum/showthread.php?t=58870
I have five molds in it right now. 150 deg with 1 60 watt and 1 75 watt light bulb.
Click to expand...

Three two part questions:
1. How long do you leave the lights on (overnight, couple hrs)?
2. What kind of vent is on the top? Just a hole with a loose piece of cardboard.
3. Will any cardboad do (display boards, dishwasher box, etc)?
Click to expand...


Mike,
1. I use a 1hr timer for most work. If I am drying wood blanks, I just plug it into the wall. Most of the time I just use one light bulb, at 60 deg roomtemp this gives me a range of about 105 to 125 depending on the wattage of the bulb.

2. I punched 3 5/8 holes on each side at the bottom and 6 5/8 holes at the top of the back. I plug the top holes with corks to vary the temp.

3. I made the box in my OP from a double-thick box we were going to throw out. A single thickness box should work but more heat will be lost thru the walls.

HD had a sale on 5/8 pink wall foam last week. I picked up a sheet and am going to make a new and bigger box when I get around to it. Will post how I made it when finished.
 
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