Micro Mark resin casting kit?

I have used Micromark's casting kit and it works well as long as you get the mold construction right and please shake the RTV material and resin well before you use them. The resin may look clear but they do separate.

KnightTemplar5150

 

Mold making is where the true art and science of casting lies. Take the time to read up on it and learn how to cut and place vents and gates, because how well a piece comes out depends on how well you remove air from the mold. Trapped air causes flaws - pits, bubbles, and short shots that ruin castings.

 

Amen to that!  One technique I use is the J-shaped pouring sprue, with vent tubes rising from the mold cavity. If you pour resin directly down into the mold cavity, the air bubbles trying to get out fight a battle with the incoming resin.  A J-shaped pour tube brings a tube down near the side of the cavity and allows the incoming resin to enter the cavity from the bottom.  You then have one or more vertical vent tubes coming up from the mold cavity to the top of the mold.  The incoming resin then forces the air out the vent tube(s), with no struggle for the air to get out.  A bit more complicated than a mold with a cavity and single hole to the top, but I guarantee you will get better castings.

bstarr3

I recently bought a Verlinden WW2 Navy deck crew figure set from eBay for $25. Since it and all Verlinden products are oop, I was wondering about buying some of their excellent figure sets while they last and making resin copies. I've never done any casting before. Has anyone used the micro Mark beginning resin casting kit? How hard is it to do casti

I believe that I heard that one time MicroMark was repackaging and selling Smooth-On's RTV and resin products.

I use Smooth-On's products,  and I am going to recommend that you go to Smooth-On's website for a couple of resons.  First of all they have all sorts of good documents & tutorials on how to do exactly what you are seeking to do.  Secondly they have a pretty extensive distributor network where you can: A) buy their stuff over the counter and B) get personal help from their experienced counter staff.  

They offer a pourable rubber starter set which has almost everything you will need

https://www.smooth-on.com/product-line/starter-kits/

You will need some Kleen Klay to half imbed the master part to make a 2-part mold.  Caution on the kind of clay you use,  Plasticine clay and some high sulfur clays will cause the RTV to not cure.  (The counter guy can help here.)   You will also need some measureing & mixing tubs.   I work in smaller volumes so 3 oz bathroom cups work.  Also some popsicle sticks to stir the stuff.  Do not cross-contaminate or you have just wasted your purchase.

Use Lego bricks to build a box.  Half imbed the master part in the clay.   Take care here,  the more careful you are the better the results.   Spray the mold with release.  Mix & pour the RTV,  it is 1:1 mix with an error window of 10% -- so you don't need to be super accurate.   Pour the RTV into a corner of the mold and let it flow up and over the mold. Tap it on a desk top to help bubbles float to the surface.   Four hours later (+/-) the RTV has hardened.   Break apart the Lego box and remove the half finished mold.   Gently peel the clay away making sure that the master remains firmly in the rubber.   You may want to cut a few alignment keyways at this time.   Reassemble the box -- now taller.   Flip the RTV half mold over and put it in the box.  Spray with mold release.   Mix and pour a second batch of rubber.   Wait for it to harden - then break apart the mold and remove the RTV.   Separate the mold halves and remove the master (If you can.  If you can't re-enginner the clay mold level and try again).  

Make or refine the pour spout into which the plastic will be poured.   You also need a vent to allow air and excess plastic to escape.

Spray the mold with release and rubberband the mold halves together,  perhaps with a couple of pieces of cardboard as backers.   Mix the plastic -- again it is 1:1 and working quickly pour the plastic into the spout until excess flows from the vent.  Demold in 5 to 10 minutes -- it is handleable but soft.   It should be hard in 30 minutes.

How did you do?  Does the part actusally release without tear out?  If not reengineer with better clay levels.    Incomplete parts cast?  Refine the mold engineering giving more thought to plastic flow,  larger spout,  more air vents.   

Repeat until satisfied.  Here is where it can get expensive.    I see where the MM set is over a hundred bucks plus shipping.  The Smooth-On set is less than half and my shipping cost is gas and travel time.   

Two part resin casting is not a quick and dirty process.  It takes time and practice to learn how to do it efficiently and more inexpensively.

I do not work for Smooth-On.  I am a satisfied user of their products.   There are other RTV and resin distributors who others have used and like.   Check your local business directory

bstarr3

How hard is it to do casting well? Any other advice?

 

If you have never done it before, there is a bit of a learning curve to things, but once you do it, casting resin is pretty simple.

Advice? Watch your measurements carefully when you mix RTV for molds or resin for casting. Some manufacturers specify mixing ratios in terms of weight and others in volume, so follow their directions carefully. Any deviations from the given ratios of components can result in messy disasters - RTV that never sets, resins that never cure and wind up like rubber, or stuff that flashes so quickly that you just can't work with it. "Eyeballing it" or playing around with another person's "secret formula" ratio doesn't work that well. Follow the instructions as if it were gospel.

Mold making is where the true art and science of casting lies. Take the time to read up on it and learn how to cut and place vents and gates, because how well a piece comes out depends on how well you remove air from the mold. Trapped air causes flaws - pits, bubbles, and short shots that ruin castings.

Take the time to make certain your master pattern is perfect before it goes into a mold. Correct flaws, remove artifacts, and prime to both ensure quality and to make the piece as smooth as possible. Smoother pieces with a uniform surface make for cleaner castings that are easier to pull from the mold.

Make a mold of stuff you normally reach for on your bench. Many times, you may wind up with a little extra resin to use up and it sucks to waste it by letting in set up and throwing it out. I keep small molds of things like bolt heads, figure hands, and heads for just such moments. This way, the expensive resin gets used up and the spares box always has the bits that I seem to use up often.

Number one piece of advice is to get some crap figures like Tamiya Panzergrenadiers or such that are cheap and practice a lot.

That MM set works fine. 

It will involve cutting the figures up in a manner similar to the way that your donor figures are- arms, head, torso with legs.

Start with the Tamiya arm and get good at making more of them. it'll take a few tries.

Good luck