Friday, October 21, 2011

Resin Head B

My first few casts of Arisu's head from the silicone mold I made had more bubbles than I liked.  So I had to figure out what was wrong and fix it.  I enlarged vents and removed the part that imbedded the magnet in the resin.  One of the molds benefited from having the resin poured into one of the vents instead of the pour spout.


The resin casts on the left are one of the first few ones made.  The casts in the middle are some of the newer casts done with minimal bubbles.  You can also see how the head looks with both parts together on the right.

The two parts don't fit perfectly as of yet.  The resin casts in the above picture have not had all their flashing removed nor been sanded.  They are still in a rough state.  Once I do some sanding both halves should fit well.

I do plan to make a few changes to the pieces because of how the molds worked.


For one, I plan to make the split line as straight as possible so that the line is just about up to the base of the ears.


I am also rethinking the way the heads fit together.  The tab I made may not be the best of ideas since that is one spot that tends to SNAP off when I unmold it.  The one in the picture above is actually super glued back on.  Maybe a magnet there instead?  So instead of just needing 2 magnets I will need 4 per completed head.

I am busy this weekend so I will try to do the sanding next week and post pictures.  I need enough daylight and good weather for the sanding since I have to do it outside with a face mask.  You don't want to breath in resin dust.  Noooooo...

Thursday, October 20, 2011

Resin Casting Mistakes and Tips

I have been casting Smooth-Cast 300 resin into my OOMOO 30 silicone mold for my BJD's head and have learned a lot from the mistakes I have made.  So let me just list them.

1.  Be patient.  Prepare, cast, and carefully remove your resin from the mold.  These things don't go well when you rush.  If you don't have the time or patience, don't bother because you will just waste your time and materials.  Worst yet your impatience can cause you to tear or damage your silicone mold.

Ex.  I did not thoroughly mix components A and B for the resin well enough.  I rushed because I thought I didn't have enough time to pour into 2 molds before the resin would start curing.  The end result was a casting I could not use.  Because I rushed the mixing, the resin did not cure properly in various areas.  Some spots were mushy and sticky.  The cast was a waste.  Not only of material, but the time.  I should have mixed well and settled for pouring into just one mold.  I may have wasted some resin because I mixed enough for 2 molds, but that would have been better than wasting all the resin and time.

2.  Measure out components A and B in 2 separate cups instead of using just 1 cup.  You might be thinking you are wasting less or will be cleaning less since you are only using 1 cup, but the reality is that it can be a huge waste.  When you mix them in the same cup, you waste valuable pot life time pouring and closing the containers.  Time that could have been better spent mixing well.  You are also likely to feel a little more rushed.  The resin I am using has a pot life of 3 minutes.  The instructions say to mix for 90 seconds then pour.  So when you pour each component into separate cups you buy yourself time to prepare yourself for the process.  The other benefit is that you can pour the mixture into the other cup, stir, and pour it back to the other cup.  This seems to ensure a better mixing for me.  If the resin is not mixed together well you will have resin that does not cure properly.

Ex.  I thought I would cut down on my cleaning if I used 1 cup to measure out both components.  (Cured resin comes out easily from the plastic cups I use.  Then I soak in soapy water and wash it later.)  It took an extra 5-10 seconds just to get from pouring to finally being able to mix.  I watched my timer and poured into my molds.  I thought I had done a good job mixing and saving some clean up.  I was wrong on many accounts.  The resin did not cure properly and created a cast that had some gooey spots.  Even when I tried to wash the resin with soapy water it continued to ooze.  The cast was a waste.  And to top it all off, the cup I used to do the mixing was also a mess.  Because the resin was not mixed well enough the resin did not cure in the cup well.  So now I had a gooey mess to clean up as well.  This took more time to clean then if I had mixed the resin well and had cured properly.

Of course your mileage may vary.  Maybe you have better luck then I do.  But I am learning quickly that when I pour in one cup, the mixing is not as good as when I measure them out in separate cups and then pour back and forth a few times while mixing.  Plus, with the resin curing properly in both cups it is much easier to clean.

3.  You need to have a good mold to get a good cast.  So this has more to do with the silicone mold than resin casting, but it is important still.  Because of how I planned the silicone mold, I had difficulty removing the resin casting.  I had to be even more patient when removing the cured resin casting or I would break parts or worse yet break the mold.  My biggest problem is from my pour holes.  They created such an odd angle that I had to try to clip the vents off first before attempting to pull the cast out with the pour hole.  But my vents were not without some issues either.  It is really hard to explain it in words what is wrong.  In a nutshell, vents placed on the top part of the sculpt would have made removal easier than vents placed on the sides of the sculpt.  I hope the next silicone mold I make does much better than this one.  Also, the locations of your vents is important.  Trapped air on your resin cast might mean that the air inside is not escaping properly.

4.  Make sure a 2 part (or more) mold is held together.  It doesn't have to be very tight, but this helps keep resin from seeping through where you don't want it to go.  I used rubber bands.  I would have used board, but I had the pour hole and vents at such an odd location that using boards didn't make much sense.

Ex.  One time I thought it wasn't a big deal to use rubber bands and forgone the use.  When I separated the molds I realized my mistake.  The pressure the resin creates inside the mold can cause it to seep where you don't want it.  So even if you think it isn't much of a big deal, it still might be.

5.  Have a face mask.  OMG, this stuff smells awful.  I don't care if your room is ventilated well enough with a fan pulling it out the window.  My mask of choice is a 3M 7502 Half Face-piece Silicone (Medium) with 3M 2097 P100 filters.  You need to make sure you properly fit it every time you use it.  Basically, if you can smell this stuff through your face mask something isn't right.  Protect your lungs.  It only took me one time to realize to USE A MASK.  Wearing gloves is a must too.  Eye protection is another one.  Do read the Material Safety Data Sheet (MSDS).

Disclaimer:  Research before you pick a product to protect your health.  I do not offer medical advice.  I am just mentioning what I am using at this moment, which may change in the future.

6.  Protect your work space.  I placed a trash bag on my work space then put newspaper on top.  The newspaper helps soak up any spills, but it will soak through to whatever is beneath it.  The plastic trash bag underneath stops the soaking right there so that it doesn't reach the table surface or any other surface.  I reuse the trash bag but replace the newspaper at the end of the day.

7.  Shake the bottles (A and B) well 10 minutes before you measure out what you need.  Why?  I notice B tends to get a lot of micro bubbles when you shake it.  The containers tell you to shake both bottles before using.  If you allow the bottles to sit a few minutes it reduces the bubbles when you measure out the components.  If you must use immediately, you can tap the cup you poured B into to help get rid of a few bubbles prior to mixing with A.  But I find it better to plan in advance and shake both bottles real well.  Then I go prepare and double check everything prior to measuring out and mixing the resin.  It doesn't have to be 10 minutes.  To be honest I am not sure how much time I do wait.  But I do know using mixing them right out of the bottle seconds after you shake them is not going to be pretty.  There will be lots of tiny bubbles.  Figure out how much time you need to wait and use that for preparation and double checking your process.

Well, that is all for now.  My resin casts from my silicone molds are getting better with the more practice I get.  Once I am happy with a few good casts I will start working on finishing one sculpt to become my prototype.  That would involve sanding, filling holes, refining detail, etc.

Tuesday, October 18, 2011

Arisu's Head Cast in Resin

From a previous post I determined how much resin to mix.

I ended up mixing a bit more.  Since A was close to the 1 Tablespoon mark, I decided to make mix 1 Tablespoon of A and B.
1 Tablespoon A = 14.7g
1 Tablespoon B = 13.3g
Total A+B = 28g

If 1 Tablespoon = 0.5 fl.oz, then I mixed a total of 1 fl.oz of resin (A+B).  That means 1 fl.oz of resin weighs 28g.


This is the first urethane resin cast I pulled from the silicone mold.  The resin used was Smooth-Cast 300.  I used a syringe (without needles) to put resin into the molds until I see resin coming out of the vents.  I should try without the syringe to see if it reduces or increased bubbles.


Although the face itself is bubble free, it seems bubbles did get trapped in certain areas.  I also screwed up the magnet polarity.  That means the 2 parts don't want to stay closed.  I removed the gates and vents and did a little cleaning before the picture you see above.

I cast one more time with the correct magnet polarity, but I was impatient in trying to remove the face plate from the silicone mold so the ear part of the silicone mold ripped.  It was very tricky so it won't be a big deal that I will have to correct future casts in that area.  I also snapped the tab on the head cast.  You can see below that piece is on the bottom right.


The casts look good on the outside.  But require some cleaning and work to make them match up properly.  At least my second cast has a proper magnet polarity.


Its when you look on the edges do you see where the rather large bubbles are.  I can hardly find tiny bubbles.  If you will notice that the bubbles are located in nearly the same places for both casts.  So some changes will need to be made to the mold to ensure the bubbles are escaping properly.


Otherwise these casts came out rather well considering.  I plan to see if I can get a better cast without the bubbles another day.  I plan to clean up and make the cast ready for use in making a production mold.  I don't have to worry about making this mold until after I get a pressure pot and air compressor.

The first cast weighed 18.8g (both head and face plates).  The second cast weighed 18.5g.  It will probably be a little more when the bubbles are all gone.

I previously estimated I needed 19g of resin to cast both parts, but it seems that is just about enough for the heads themselves and doesn't leave enough for gates and vents.  So it is a good thing I mixed more than I needed, but it is a good idea to still lessen the amount of waste produced.

If I mix 3/4 fl.oz of resin (A+B) and 1 fl.oz of resin is 28g, then I need 21g of resin.
Weight of 3/4 fl.oz of resin = (28 / 4) * 3 = 21g

So in the future I will mix 11g of A and 10g of B by weight.  Or 3/8 fl.oz (3 drams) of each A and B by volume.
A = 21 / 190 * 100 = 11.05g
B = 21 / 190 * 90 = 9.95g

How much resin? (Math Heavy)

Smooth-Cast 300
Mix Ratio by Volume = 1A:1B
Mix Ratio by Weight =  100A:90B
Specific Volume = 26.4 cu.in per pound

Goal
Find out how much resin I need either by volume or weight that can be easily mixed.

Volume to Weight Conversion of Materials
1 cu.in. of Van Aken Modeling Clay (which is the oil clay I use) weighs 30.9 grams.
1 cu.in. of my Carving Wax weighs 25.3 grams.

To get these numbers, I just made a cube that was 1" all around and weighed it.  Of course these numbers are just rough estimates.

The head used to make the 4-part mold weighs 23.6 grams.  The head is mostly Carving Wax, but also has some oil clay.



If the head was pure oil clay, I would need 0.76 cu.in. of resin.
Volume of resin = Weight of sculpt in grams / Weight of 1 cu.in. of oil clay
Volume of resin = 23.6/30.9 = 0.76

If the head was pure carving wax, I would need 0.93 cu.in. of resin.
Volume of resin = Weight of sculpt in grams / Weight of 1 cu.in. of carving wax
Volume of resin = 23.6/25.3 = 0.93

If you notice I would need less resin if the head was made of oil clay than if it was made of carving wax.  The head is mostly carving wax, so I have decided to just go with assuming it is pure carving wax.  I will also round up and say the head was 1 cu.in.

Amount of resin needed is:  1 cu.in. (which is volume)

Is that easily measured out?  No.  So I will convert to measuring by weight.

If a pound of resin is 26.4 cu.in.  So 1 cu.in. of resin would weigh 0.61 oz.
1 cu.in. of resin = 1 (lb) / 26.4 = 16 (oz) / 26.4 = 0.61 oz.

So if the head is 1 cu.in. and 1 cu.in. of resin weighs 0.61 oz.  Then it is safe to say I need 0.61 oz of resin for the head cast.

So now I need to figure out how much of A and B I need.  The ratio is 100A:90B.
Part A = (1.65 / (A+B)) * A = 0.61 / 190 * 100 = 0.32 oz.
Part B = (1.65 / (A+B)) * B = 0.61 / 190 * 90 = 0.29 oz

So, how much resin do I need by weight?
0.32 oz A : 0.29 oz B
-or-
9.07 g A : 8.22 g B

But because there are vents and the pour gate to consider, I will increase the amount by 10%.

So using grams, I would need 9.98g A and 9.04g B.  Lets just round it up to 10g A and 9g B for a total of 19g of resin.

Monday, October 17, 2011

Arisu's Head Silicone Rubber Mold: Part 3 & 4

This is the last of the 4 part mold for Arisu's head and the most difficult.  It took over a week to finish.  (I did a little here and there with a few days off of course.)  I planned to make a build up of non-sulfur oil clay inside the head to the thickness of what I want the resin to cast.  The difficult part was to have both halves line up when you sculpt them separately.  This includes placement of magnets, guides (rails or tabs), and thickness.

As luck would have it, my first set of silicone molds is perfect for another idea.  I cut out a chunk of silicone from the junk molds to create a pour spout and cast hot wax in it.  I poured out the wax after a few moments to create a hollow cast of the head.  Keep in mind the mold I altered for this idea is a JUNK mold.  A MISTAKE mold.  It is NOT the mold I am trying to make to cast a prototype of Arisu's head.  I would never cut or alter an already made mold I planned to use for production.



My carving wax has a shrinkage of about 2-2.5% so it does not fit snug in the mold, but that is not a problem for what I am planning to do.  The small gap can easily filled in later with wax or sulfur-free clay.


I cut the head apart using the true head mold as a guide as to where the line should be.  This gives me 2 head parts with even thickness.  After the edges and parting lines are fixed, I removed where the eye would go.

The next part would be to figure out the mechanics of the magnets, pour hole, and vents.  I also increased the thickness by adding some sulfur-free oil clay inside the head.


The foam board is cut to create a wall around the silicone and is sealed with a low temperature glue fun to ensure the rubber doesn't leak out.  After mold release is applied, the molds are now ready for silicone rubber to be poured.


Part 3

The volume to be filled with silicone rubber is 2.5"x2.5"x1.25", which is 7.8125 cu.in.

The volume of half the head is 0.89 cu.in (with radius of 0.75").  If the clay wall in the head is 1/8" thick, the volume of the remaining half of the head is 0.52 cu.in (with radius of 0.5").

The volume for the neck is 0.1 cu.in.

The total volume of silicone rubber needed for this part of the mold is 7.81 + 0.52 - 0.1 = 8.23 cu.in.

The weight of the silicon rubber (A+B) is 6.4 oz.  This is 2.78 oz A and 3.62 oz B.

For more information about my math doing these calculations, see Part 1.


Part 4

The volume to be filled with silicone rubber is 2.5"x2.5"x0.5, which is 3.125 cu.in.

The volume of half the head is 0.89 cu.in (with radius of 0.75").  If the clay wall in the head is 1/8" thick, the volume of the remaining half of the head is 0.52 cu.in (with radius of 0.5").

The volume for the neck is 0.1 cu.in.

The total volume of silicone rubber needed for this part of the mold is 3.125 + 0.52 + 0.1 = 3.745 cu.in.

The weight of the silicone rubber (A+B) is 2.91 oz.  This is 1.27 oz A and 1.64 oz B.

For more information about my math doing these calculations, see Part 1.


Part 3 & 4

The total weight of silicone rubber (A+B) needed for Part 3 & 4 is 9.31 oz.

For measuring by volume, 7/8 cup of A+B is 9.66 oz, which is a 3.8% increase.  If I used 1 cup of A+B, that is 11.04 oz and a 18.6% increase.  Since it won't be easy measuring by volume I will be measuring by weight this time.

For a 10% increase I would need 10.24 oz of A+B.  That would be 4.45 oz of A and 5.79 oz of B.



I actually poured less than I estimated in 2 separate parts.  The first pour was to ensure a good bubble-free coating as possible on the sculpt.  I then added some scrap silicone rubber to decrease the amount of fresh silicone I would need.  The second pour was to finish filling the mold box.


The 4 part mold for the head is now done.  Next step is to cast the head in resin.  Can't wait to see how the head will look in resin.


It looks just awesome... and kinda freaky.

Part 1
Part 2
Part 1 & 2 REDO

NOTES:  I am using the Mold Making & Casting Pourable Starter Kit that I had purchased from DickBlick.com.  This kit is made by Smooth-On.  The silicone rubber that comes with the kit is OOMOO 30.  The kit comes with an instructional booklet and a DVD with video on how-to make molds and to cast.

OOMOO 30 Conversion Table Volume and Weight

So far for my silicone rubber molds using Smooth-On OOMOO 30 I have been determing how much I need by weight.

My post Arisu's Head Silicone Mold: Part 1 goes indepth about how I determined the amount of OOMOO 30 I needed in ounces by first determining cubic inches of space to fill.  Even with a scale I sometimes prefer to measure by volume instead of by weight.  After I made a few molds I was able to make myself a conversion table.  It is not 100% accurate, but it gives a rough idea.


Part A, Part B, and Total are all measured in ounces.  I added horizontal highlights to help me reference numbers better.  I can clearly see that if I want to make 11 oz of silicone rubber, that I should mixing 1 cup of rubber.  That means 1/2 cup of A and 1/2 cup of B.  That 1/2 cup of A should weight close to 4.8 oz and 1/2 cup of B should weigh close to 6.24 oz.

Ratio by Weight:  100A:130B
Ratio by Volume:  1A:1B

NOTE:  Your results may vary, but this table is working out well for me.

Friday, October 14, 2011

Arisu's Acrylic Eyes

I bought some 10mm half round acrylic eyes off ebay to see how they would look in Arisu's carving wax head.  These eyes do have a raised lens, which I am not to fond of. Looking forward the eyes are fine, but if you decide have the eyes look in another direction you now have that raised lens getting in the way.


The iris is 5.5-5.8 mm in diameter, which suits Arisu well.  The iris is more pixelated than I like though.

By early next week the silicone molds for her head should be done and the first prototype of her head cast.

Monday, October 10, 2011

10mm Eyes Project: Part 5

The clear resin I will be using is Castin' Craft Easy Cast (Clear Casting Epoxy).


Since it is likely I will be using Easy Cast in small amounts I decided to test having them in a more easily dispensable container.  I have empty bottles like the Vallejo paints which I labeled Hardener and Resin.  If my paints are still good in their bottle after 5+ years, then maybe this will work... right?  Now I can dispense a drop at a time.  For this particular project I used 5 drops of each onto a tin muffin cup.  (And that was still too much resin mixed.  I can't imagine trying to pour that amount from the original bottles.)


The first application of clear epoxy resin was to coat the entire eye and fill the dip of the pupil.  According to the instructions it came with, 'thin castings will take longer than thick castings'.  So how long?  Not sure exactly, but less than 24 hours the resin was hard to the touch.

Since the eye would wiggle around its holder (an upside down lego piece), I put some clay in the holes to help secure the eye.



The second application was to round the top of the eye by slowly applying resin with my wooden stick to the top of the eye one drop at a time.

In less than 12 hours it is soft cured.  I waited longer than 24 hours to ensure it is hard cured before I wet sanded the eye with a 1000 grit sandpaper.


Her first pair of doll eyes are now ready.  Not a bad first attempt, but you should be able to clearly see that one eye has a smaller pupil and iris than the other.  Also, I think the iris itself needs to be bigger, so I will be making another mold.  These eyes make her look surprised.

Note:  This part of the project took several days to document before it was posted.

Saturday, October 8, 2011

Arisu's Head Silicone Rubber Mold: Part 1 & 2 REDO

Although the molds for Part 1 and 2 were acceptable, I was still not happy.  Why?  Because I realized I didn't like how far forward her neck joint was on her head.  Since I was going to fix her head and redo both molds, I figured I might as well do the faceplate line better.  If I wanted, I could just use the first pair of silicone molds made, but I am just going to say they were a good test run.

This time Part 1 was the mold for the back of the head.  This allowed me to make the proper lines around the ears.  Below you can see the first part is done and the second part is ready to be poured.


Then it was time for Part 2 which would be her faceplate.

This is when another problem came up.  Before I was mixing and pouring my silicone at 75F.  Then I mixed and poured at 80F, which was the problem.  The silicone mixture was not as viscous as I remembered it being previously.  I could no longer do a steady thin stream of the silicone mixture.  It was starting to pour lumpy with thin stream to fat stream to thin stream again.  This resulted in the face having many bubbles since it couldn't flow over the head details smoothly.

So I chopped up the failed mold and this time had the room temperature at 75F.  (Live and learn.)  I used the chopped up silicone to fill in voids so I would not have to mix as much fresh silicone.  I made sure the chopped silicone was not near the face details to ensure the head part gets coated well with fresh silicone.  This should help me cut down some of my losses.  (This stuff isn't cheap.)


So now her she has new Part 1 and Part 2 head molds.



Part 3 & 4

NOTES:  I am using the Mold Making & Casting Pourable Starter Kit that I had purchased from DickBlick.com.  This kit is made by Smooth-On.  The silicone rubber that comes with the kit is OOMOO 30.  The kit comes with an instructional booklet and a DVD with video on how-to make molds and to cast.

Blog Disclaimer

Content
This blog is a personal journal about my journey in the world of ball jointed dolls.  As such, this blog is for my benefit first and foremost.

It is not my intent to offend others while expressing my own thoughts, ideas, and experiences in any way and it is hard to say what exactly offends others.  If who I am offends you, please feel free to exit this blog at anytime.  I will not be offended if you didn't say good bye first.

I try to convey my thoughts as clearly as possible but there may be grammatical errors, misspelled words, incorrect sentence structure, or other reasons to suspect I did not get good grades in English.  (I got okay grades but I really did hate English class.  Sorry, if I offended any English teachers out there.)  It can also be easy to misunderstand written words.  Remember that this blog is written for my benefit so I at least need to understand myself... and I sometimes fail at that too.  I am human, so please remember that errors do happen and forgive me for my mistakes.

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With time contents of older posts may become outdated.  I may change my mind about what products I use, thoughts, ideas, processes, or my favorite color.  (In case you wanted to know I like black and silver.)  I have an open mind and am willing to make changes if it works for me.

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I am not responsible for YOUR health and safety when it comes to the use of products mentioned or process.  What does that mean?  It means read the instructions on products you buy before you use them.  Companies write and include them for a reason.  If my information conflicts with the company information, follow what the company says and not what I write or did.  You are responsible for your own health and safety.  How often do we buy products that we never read the instructions for?  This is your life.  Protect it.  Many of the products used in doll making can be toxic to you in some way and require safety measures.

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This blog is for me but is made publicly available for others to read.  Use the information contained in this blog at your own risk.

Disclaimer for my Disclaimer

It was not my intent to offend anyone with my off humor or style of writing.

Really though...  You can go insane trying to protect yourself with a disclaimer when all you are trying to do is document your journey and make it publicly available so that others may benefit as well.  I am a bjd hobbyist.  I am no expert or professional.  I am not a surgeon when I use sharp objects.  I am not a chemist because I mix part A and part B.  I am not a mathematician because I can add.  Please, just enjoy my blogged journey.  Thanks for reading.

Um, do I need a disclaimer for this too?

Friday, October 7, 2011

10mm Eyes Project: Part 4

Time to paint the pair of eyes I made in urethane resin.

First I wet sanded down the eyes with 1000 grit sandpaper.  After drying it was time to paint.

I decided to use what I already had.  Vallejo Game Color paints.  (They are over 5 years old but are still good after an intense shaking.)


I decided to make a pair of blue eyes for my doll.


Do you know how hard it is to paint an area less than 4mm with as much detail as you can?  Try it.  O.o

I first painted the blue which was mixed with some metallic silver.  What is the point of the metallic?  Regular grey could have worked to help dull the blue a tad, but I am hoping the use of metallic paint may give some reflective properties to the eyes.  After the base blue is painted, I dab a little black for the pupil.  I then lined the outside of the blue iris with a darker gray metallic.  I used a wash made from the blue/purple and gray to help add some depth.  Really though...  Can you even see detail at this level?  At the end I again added some black into the pupil.


Wow, it looks worse close up then it did when I was working on it.  The paint looks so lumpy.  Will it matter?  It doesn't look lumpy when I am looking closely at them.  Sometimes I don't like the macro settings.  We will see how it looks when the clear resin coats it.

NOTE:  This part of the post was actually done yesterday.  I was planning on also including information about coating the eyes with clear resin in this post, but it seems to be taking a while to cure.  So I will just post the painting part of the progress and post about the clear resin part when that is done.  And that can take days if this thing takes over 24 hours to cure each layer.  I am also planning on casting at least another pair of eyes to get more practice making better eyes.

Wednesday, October 5, 2011

10mm Eyes Project: Part 3

I first made my carving wax eye, then made a 2 part silicone mold for it.  Today I cast in urethane resin for the first time... small scale.

I mixed 5 cc of Smooth-Cast 300.  That is less than 1/4 an oz.  Do you know how hard is it to pour that much liquid?  Well, the pouring I suppose isn't a problem as long as you stop quick enough, but the mess that follows is something else.  But practice makes perfect... or makes thing a tad better and the mess less.




Nice time progression.  I used a stop watch to help me know when 90 seconds of stirring was up and to pour quickly.

Since it is a 2 part mold with no extra vents, I poured into the first half then put the mold together before pouring the rest.  This ensured the bottom portion casts properly.


Above you can see how it looks like when I remove the top mold after the resin has cured.  Even after curing for 20-30 minutes the rod part is a bit flexible.


Here you can see how the original eye looks compared to the new resin eye.  The resin eye looks rather white but it is actually a little off white when compared to the plastrut rod used on the carving wax original.


Above you can see the 2 resin eyes I made.  Not the best picture though.  I hope to paint them soon and then seal with a clear epoxy resin (which I still need to get).

The great thing so far with making the silicone molds and casting in urethane resin is that the cups and stir sticks can be reusable.  Some cleaning is required.


You can see above that I ended up mixing tooooooo much resin.  It is just hard dealing in small quantities.  You can also see a tiny resin rod from my first attempt at pouring a put together mold.  The air in the eye part could not escape.  That is why for the other 2 casts I poured into the bottom mold first before putting both mold parts together to finish pouring the rod part.  It worked out great.

In the future I plan to make a mold that will allow me to cast multiple eyes at the same time.  I am not sure whether it would be 2 eyes or more pairs at the same time.  That would reduce the amount of resin wasted.  But do I really need that many eyes?

Tuesday, October 4, 2011

10mm Eyes Project: Part 2

I am going to make a 2 part silicone mold of the eye I made earlier.


So how much silicone rubber will I need?

Mold box is 1.25" x 1.25" x .75 = 1.17 cu.in., which is .91 oz.  That is 0.4 oz of A and .51 oz of B.  Since the eye and mold key (the ring with a triangle and circular marks) are rather small, I didn't subtract them from the total silicone rubber needed.


The silicone rubber for this mold was poured the same time the second mold for Arisu's head was poured.


If you click on the image above you can see that I didn't mix the A and B very well.  You can see some streaking of pink, but the mold still came out fine.  There also appears to be a very tiny bubble where the pupil is, but this should not be a problem since the pupil dip is just to contain a dot of black paint.

After cleaning and preparing the mold, it is ready for the second pour.  (Of course not forgetting to use the parting agent as directed.)


The volume of the second pour is 0.78 cu.in (1.25*1.25*0.5).  That is 0.34 oz A and 0.44 oz B.  Since this is such a small amount, I decided to use my gram scale.  So I will need be 9.64g of A and 12.47g of B.



The next step would be to see how it turns out when I cast using urethane resin.

Arisu's Head Silicone Rubber Mold: Part 2

 Now it is time to make the second part of the mold.



The volume of the space to be filled by silicone rubber is 2.5"x2.5"x1.25", which is 7.8 cu.in.

The head is approximately 1.25" in diameter.  The volume of a circle with 0.75" radius (which is half a diameter) is 1.767 cu.in.  Half the head is in the space so I would need to remove 0.89 cu.in.

The neck area is approximately 0.5" long with a 0.25" radius.  The volume of the neck is .1 cu.in.

The volume of silicone rubber needed = volume of box + volume of neck - volume half head = 7.8 cu.in. + 0.1 cu.in. - 0.89 cu.in = 7.01 cu.in.

This part will need 0.34 pounds or 5.44 oz of silicone rubber.

So I would need 2.365 oz of A and 3.075 oz of B.

I will also be making the silicone mold for a 10mm eye at the same time.  The eye mold will need .91 oz of silicone rubber.  That is a total of 6.35 oz.

So I will actually need 2.76 oz of A and 3.59 oz of B.  

For the first mold I poured 7.36 oz of A+B = 2/3 cups.  So if you do the math 1/3 cup = 3.68 oz.  That makes 1 cup = 11.04 oz.  Then 1/2 cup = 5.52 oz.  These of course are rough estimates but should give me a good ball park number.

For the first mold I estimated needing 6.56 oz of silicone rubber but ended up pouring 7.36 oz, which is a 12% increase.  Some of the silicone remains in the cup, on the stirring tool, missing the mark, etc.  So it is good to take into account needing a little more, but you also want to minimize waste.  If I did a 10% increase of 6.35 oz, I would need to pour 7 oz.  That would be 3.04 oz of A and 3.96 oz of B.  Or I could do by volume which would be 5/8 cup (A + B).


One thing I did notice is that the area around the ears will not cast the way I want them to.  Instead of pouring the facial features first I should have poured the back of the head.  This would have allowed me to separate the face plate better where the ears are.  Sometimes you don't see an issue until you try.  At least I know how to fix it for next time.


The two halves came apart rather easily, which means I used enough release agent.

There is a tiny air bubble on the bottom of one of the ears but the rest looks good.  Not bad so far.  You can even see where the nostril holes are.  (I am actually very pleased with the molds so far, but I won't know how good the molds are until I get a chance to cast with urethane resin.)

The next part is going to be the most difficult since I need to add clay inside the head where I want resin to be.  I would be also adding the pour holes and vents.  To get a better idea of what I am doing, check out my post about my BJD Head Mold.

When mixing A and B for the silicone rubber, you can reuse your cup and stir rod if they are non-porous.  The cured silicone rubber comes off easily enough with the thicker parts pealing like a sheet.


For this mold I weighed the waste silicone rubber and came out to 0.5 oz.  The waste from the first mold came closer to 2 oz.  I have almost used 1 pound of silicone rubber thus far and the kit I am using is 2.9 pounds of OOMOO 30.

Part 1
Part 1 & 2 REDO 
Part 3 & 4

NOTES:  I am using the Mold Making & Casting Pourable Starter Kit that I had purchased from DickBlick.com.  This kit is made by Smooth-On.  The silicone rubber that comes with the kit is OOMOO 30.  The kit comes with an instructional booklet and a DVD with video on how-to make molds and to cast.

Arisu's Head Silicone Rubber Mold: Part 1

Arisu's head will have a 4-part mold.  This is the first mold being made.  To be precise, it is the first silicone mold I have ever made.


Clay is built up around the sculpt and mold keys are made.


I created a mold box using foam boards which were sealed using a low temperature glue gun.



Now that the mold box is ready, I have to figure out how much silicone rubber I need to pour for the first part.


The volume of the space to be filled by silicone rubber is 2.5"x2.5"x1.5", which is 9.4 cu.in.
Volume of a rectangle = l w h

The head is approximately 1.25" in diameter.  The volume of a circle with 0.75" radius (which is half a diameter) is 1.767 cu.in.  Half the head is in the space so I would need to remove 0.89 cu.in.
Volume of a circle =  (4/3) π r 3

The neck area is approximately 0.5" long with a 0.25" radius.  The volume of the neck is .1 cu.in.
Volume of a cylinder = π r 2 h

The volume of silicone rubber needed = volume of box - (volume half head + volume neck) = 9.4 cu.in - (0.89 cu.in +.1 cu.in.) = 8.41 cu.in.

According to the Technical Bulletin for OOMOO 30 the Specific Volume is 20.6 cu.in per pound.  So 8.41 cu.in / 20.6 cu.in will tell me I need .41 pounds of silicone rubber.
Weight of silicone rubber needed = Volume of silicone rubber needed for the mold / Specific Volume of the silicone rubber

The Technical Bulletin also states that the ratio by weight is 100A:130B.  So I would need 0.1783 pounds of A and 0.2317 pounds of B.
A needed = (Weight of silicone rubber needed for mold / (A+B)) * A
A = (0.41 pounds / (100+130))*100 = (0.41 pounds / 230)*100 = 0.1783 pounds
B needed = (Weight of silicone rubber needed for mold / (A+B)) * B
B = (0.41 pounds / (100+130))*130 = (0.41 pounds / 230)*130 = 0.2317 pounds

Converted to ounces it is 2.85 oz of A and 3.71 oz of B.
Convert pounds to ounces:  ounces = pounds*16

So using my ounce scale I will be measuring out 2.85A:3.71B.  When they are poured, they should be 1A:1B by volume.

After applying sealing agent and releasing agent, it is finally time to measure and mix the silicone rubber.


I ended up pouring 3.2 oz of A and 4.16 oz of B, which is 1/3 cup of each.  (I tried to stop at 2.85A but it flowed a little to quickly and I figured I was close to the 1/3 cup mark anyways, so I continued to pour until the 1/3 cup line.)  This created just the right about of silicone rubber to fill the mold box. This minimizes waste but also ensured I had enough silicone rubber for the mold.

After 6 hours of curing, my mold is finally cured and it is time to remove the mold box.  The clay build up is removed but the head is left in the silicone mold.


I am rather happy with the results.  There were some tiny bubbles in the tiny key dots, but this shouldn't be a problem.

Part 2
Part 1 & 2 REDO
Part 3 & 4 

NOTES:  I am using the Mold Making & Casting Pourable Starter Kit that I had purchased from DickBlick.com.  This kit is made by Smooth-On.  The silicone rubber that comes with the kit is OOMOO 30.  The kit comes with an instructional booklet and a DVD with video on how-to make molds and to cast.