I've added an new bracelet video to my YouTube channel. Check it out.
Using a horizontal mold, you can create single pen blanks or a block of resin that can be cut to size.
There are a few vendors that make horizontal molds for both block and single blanks. Fred Wissen
(http://www.ptownsubbie.com/) has very nice molds that are made of a flexible rubber. I think it is a silicone based compound.
Then you have the plastic type molds made by Castin’ Craft. They are block molds that are: MC7: 8
ounce RECTANGLE - 3" x 5" x 1-1/16" and, MC8: 9 ounce - RECTANGLE - 3" x 6" x 1-1/16". These are two that I have used in the past. They work better if you use a release agent.
Making your own mold is very easy. There are several methods that give you good results. I’ll start first with the cutting board mold. Using a plastic cutting board from one of the big box stores, you can cut
it into strips. By screwing the different parts together to form a rectangle mold, you can pull apart the mold
when the resin is cured by remove the screws and dissembling the mold. You can find good examples and even a cut list with a Google search of cutting board molds.
Next methods would be making a mold from 100% acid cured silicone sealant. You can buy the silicone
at your home improvements store. You can tell if it is the right material if it smells like vinegar. When I made a mold, I created a “positive mold’ form, cover it with saran wrap, squirt the silicone into a soapy
bucket of water to make it easy to handle, and formed the silicone into the positive mold. Sorry, I’m not
trying to provide building instructions, just give you the basics of the process.
I’m sure there are others but the last horizontal mold idea I have would be to create your own mold with silicone rubber. The link to my video is in the previous post.
I’ll split the molds into categories: Horizontal and Vertical.
You have many options for Vertical molds. I’ll start by discussing Schedule 40 PVC. It is what I use to casting in. The inside diameter of the 1/2”, 3/4” and 1” pipe work well for pen sized blanks. The Poly Resin is a heat cured process so as the blank sets, it will shrink. That shrinkage will all you to remove the blank from the PVC. I normally use a wood dowel and a rubber mallet. I’ve had some people complain that they haven’t been able to remove the blank from the PVC. I think this is because the blank hasn’t full cured.
(Caution: the next step should be used at your own risk)
I fully cure my blanks in a low heat oven. I caution you not to put the blanks in liquid form in the oven. By low oven I mean the lowest setting. Ours is 170 degrees. I wouldn’t exceed 200 degrees. You can use a toaster oven but I haven’t had much success using one. I always get the blanks too hot and melt the PVC, and it is flammable. I wait until the resin is solid to the touch at the top of the PVC pipe. If you don’t want to use the oven method, you can sit the blanks in the hot sun and this should cure them. I don’t use any type of mold release.
There are several different methods to plugging the end of the PVC. I use #10 corks that I buy from WidgetCo. (http://www.widgetco.com/) I’ll use some type of plastic food wrap to cover the cork before I insert it in the tube. I try to keep the resin from soaking into the cork. I can get 15-25 uses out of the cork stoppers. Some people have had luck using rubber stoppers. The advantage of rubber is that the resin won’t ruin the stopper.
Some casters use different type of tape to seal the end of the PVC pipe. Again, I have tried it but was more successful with cork stoppers.
Note: PVC should not be used for Alumilite unless you plan to use the lathe to turn off the PVC from the pen blank.
There are several vendors that make vertical molds using urethane or silicone rubber. One
that comes to mind is Fred Wissen at http://www.ptownsubbie.com. He has 3/4” x 6” blank rubber mold.
If you feel advantageous and want to make your own molds, I have a video on Youtube on using Smooth-On’s (http://www.smooth-on.com) OOMOO 30 silicone rubber. It is an easy to use compound that doesn’t
require vacuum degassing and is easy to mix and pour. Check out the video here (http://youtu.be/E7LgSzuzXt0)
I’ve seen others use baby soda bottles. I haven’t tried it. Just seems that the blanks would be hard to get out. One advantage, you wouldn’t have to cork the mold. One last item before I close this blog
post. I have used aluminum wrap or foil to make a one-time use mold. I took some foil and wrapped it tightly around wood dowel of the size I wanted for my finished blank. I guess you could use another pen blank. Most likely the foil will stick to the resin and have to be turned off.
I took the photo to the left from US Composites website. I primarily use the pigments they sell made to color polyester resin. (http://www.uscomposites.com/pigments.html) You can mix these pigment to make other colors. Just get out your old color mixing wheel. I started purchasing 1 ounce bottles then moved up to the 4 ounce size. Like mica, a little goes a long way. These are opaque pigments so there would be no need to paint the tubes with these blanks. US Composites also sells 4 transparent pigments that are fluorescent.
I have tried many other things that I didn't think worked at well. Things like Testor model car paint, finger nail polish, acrylic paint and properly others. I even tried powder coating products that do not mix well. My advice is to stick with the colorate designed for resin. Feel free to comment below on other things you have used to color your resin. Below are blanks that I made with solid pigment.
Mica Powder is a finely ground powder that has various uses. It is used to in makeup, polymer clay and coloring resin. I buy mica from Coastal Scents (CS) or The Conservatorie. A few times a year CS will run a 30-50% discount sell on all of their mica. I normally stock up because a little goes a long way. You can purchase samples (tablespoon) of any color for $1-$2 each. They come in little zip lock bags and are shipped cheaply by UPS. I can make several casts out of a little bag. Normally, I purchase 4 ounce jars of mica.
Mica blanks most likely will need the tube painted. If you don't, the brass tube will show through the blank.
In some cases, you can mix the mica to make different color variations. Below are some blanks that were made with mica powder.
Another type of powdered pigment that give similar effects to mica is Jacquard Products Pearl Ex. (http://www.jacquardproducts.com/pearl-ex-pigments.html)
For this blog, I will only discuss Polyester Resin that I use to create turning blanks. To the left, you see a screen shot of U.S. Composites’ website. This is the primary vendor I use for my polyester resin. I use the Silmar 41 Clear Polyester Casting Resin. The resin can be purchased in quarts, gallons and 5 gallon buckets. I started with gallons and now I purchase 5 gallons at a time.
My calculations say that I have between 1.5 and 2 ounces of resin in a 3/4" x 6" pen blank. Using a gallon of resin as an example and 2 ounces as a blank size, I can get 60-64 blanks out of a gallon of resin. (Assuming I have very little or no waste) Currently, US Composites (USC) (http://www.uscomposites.com) has gallons for $37 each and to Kentucky the shipping is about $20. Total is $57.
My goal here is to show you the cost per blank of the resin. $57 divided by 128 (@ two ounces per blank times 64 blanks to get the 128 number) equals $.45 per ounce; multiply that by 2 ounces equaling $.90 per blank for a gallon of resin. I took all the numbers on the high side so $.90 is high.
Like many people, I started with casting resin I purchased from a craft store. Most of them have 40-50% off coupons for a single item. Last time I looked at Hobby Lobby, Casting Craft (CC) quarts of resin were $29.99. Using the same formula, 50% discount on the resin and not adding tax, Casting Craft resin cost around $.94 per blank. I'm not putting Casting Craft resin down. I'm just showing the cost is really higher than ordering a gallon online. I made acceptable blanks with CC resin. I feel the Silmar 41 resin makes a much better blank.
Be aware when you purchase 5 gallon buckets, USC has to add a hazardous material fee from UPS. I break the resin into gallons. I purchased some empty gallon containers from USC. Generally speaking, I can get the per blank cost of resin under $.75 per blank with 5 gallon purchases.
iLLSTREET Composites is another vendor that sells Silmar 41. The polyester resin is shipped with methyl ethyl ketone peroxide hardener. If you aren't sure how to use the resin, check out my video channel on YouTube. (http://www.youtube.com/user/fool4peppers)
In the blog, I have only discussed polyester resin. Another casting resin that can be used is Alumilite. I have used this resin before but have more experience with Silmar 41. I will not attempt to debate the pros and cons of the two resins. With Alumilite, you must use a pressure pot to remove air bubbles. In a later blog, I'll discuss pressure pots and air bubbles. Stay tuned.
Next blog, I'll discuss coloring.
I'm a beginning woodworker playing with simple projects I can complete quickly.