Not in a Hurri......an experiment

[Rafael]

Not in a Hurri?. Well, maybe I am, after all.

What I'm certainly not is hurried.

I'm procastinating on my Orlyonok Ekranoplan scratchbuild.

I want to make so many whiffs that when I see my stash, I despair. I have one each of every subject I want to make. But each subject is good for two or three variations, or more.

Since materials and kits are no longer on sale in my country, and having severe restrictions to buy from the internet (almost impossible, thanks, govt!) I started thinking about casting parts from the kits I already have.

But, cast with what?, well the only things I could find available were silicone caulk, automotive body repair resin and putties.

So I go with what I can find. Let's see how it comes out.........

Yerterday, I started molding major parts from my only Hurricane. Note the caulking gun in the background. A few key pieces for this build were left out of the pic for suspense's sake


Covered the pieces and myself in acrlylic paint-tinted silicone+gliceryn. This mix is known for its faster setting. I intend to make open-faced molds, so no ducts for pouring were implemented.


Then, a couple (well, four) hours later, a skin and certain amount of the silicone were set, and I covered the whole gooey mess with plaster, to form a hard back or mother mold.


This morning, after letting it sit overnight, I turned my molds over and extracted my masters. Amazingly, they came out without trouble. The action of gliceryn as a catalyst has the added advantage of reducing the silicone's adherence to some materials silicone doesn't like already. So no release agent is needed, at least with styrene.


When it casts, it pours!!!. I poured my resin. Cut with a goodly amount (50%) of bondo filler (not glazing) putty, intended to give color and a more easily sandable texture. It sits on my bench as of this moment. In a couple hours, I probably be able to de-mold.


Well, that's it for now.

Ah! I forgot. If everything comes out well, as I hope, my build will be a...-you guessed it!- Hurri in an unusual configuration. And for the very first time in a good while, I'm going to decal it with israeli markings.

Cross your fingers, and enjoy!!!

Rafa

[PanzerWulff]

Thats AWESOME!!! Rafa it's cool how you make the most of whatever building materials you have.I can't wait to see more
"Panzer"

[Jeffry Fontaine]

This page over on the Modeling Madness Site might be of interest to you since it has several topics that are related to the fabrication of molds and resin.  Specifically the method that you are describing with the use of automotive related materials.  Go to http://www.modelingmadness.com/howdoi.htm and save the pages to your hard drive.  There are images provided that show a great amount of detail on how the process is done. 

[nev]

We have a saying in Britain Rafa - "necessity is the mother of invention" 

[B777LR]

We have a saying in Britain Rafa - "necessity is the mother of invention" 

We have a similar saying in Denmark. Translated it would be "Necessity learns nakid women how to sew"

[Shasper]

Rafa, keep us updated on how this goes, I'm curious to see how your new found method of casting will workout 'fore I try it m'self!

Shas

[Brian da Basher]

Seeing techniques like this makes me feel like I merely play with toys. I'm absolutely amazed Rafa! You somehow manage to do so much with so little. I'd be hard pressed to keep going under such circumstances but you not only persevere but do so masterfully!

My hat is off to you muchacho!

Brian da Basher

[John Howling Mouse]

Brings back memories.  Say, I realize you work in a fairly cramped space (with a balcony) so please confirm that you are always wearing a proper respirator mask c/w the right type of catridge filters (a dust mask will not protect you) and using latex gloves!   Everything you're working with there is either highly dangerous to your brain, lungs and/or carcinogenic.

Small tip: to reduce the amount of sanding you will need to do on the open face part of each casting, try covering the castings with an absolutely flat piece of rubber mold slab (use a release agent) as soon as you pour the resin in.  This works with the meniscus property of the cast resin to produce a nice, ultra-flat open surface on mating surfaces.  If you de-mold only to find air bubbles, try vibrating a board that the molds sit on right after you pour (I leave that to your imagination).

[Maverick]

Bueno, bueno, mi Pana!

As always, my hat's off to you big time Rafa.  Your ingenuity knows no bounds.

Tu Amigo,

Mav

[SinUnNombre]

Great work, Rafa. I'm interested in exactly how you did it, because I would love to get into the casting business. Could we have some more details, please? I can't wait for the final result.

Luego vato.

Jon

[BlackOps]

Very creative thinking!  It's good to see you've found a way to make it work even though you have lots of obstacles. Hope everything comes out well

[B777LR]

How did it go?

[Rafael]

OK. An advance report:

Good and bad.

GOOD:

a) The molds kept their shape, didn't shrink,
b) They captured the master's detail exquisitely crisp. This is a Revell Hurri.
c) They're flexible, not crumby, and conform neatly to the master's surfaces.
d) The resin casts got the detail level transferred to their surface with extreme precision.
e) The resin casts release from their flexible mold with no problems, without release agents.

BAD:
a) I put the blame on my technique. The molds, on close inspection, are full of bubbles in the master/mold interface. UNACCEPTABLE!!!
b) The mother mold, or hard back has problems reattaching to the flexible molds. This is due to an error I made at the time of crafting the molds. I should have smoothed out the outer surface of the flexible mold, in order to obtain a smooth interface with the mother mold. This caused my left fuselage side to warp and distort. UNACCEPTABLE!!!

Solutions I plan to implement:
a.1) Apply the silicone paste with a fingertip, in a very thin layer, let dry, and build up silicone on top of that
a.2) Brush the stuff on, let dry and build up
a.3) thin my silicone, cutting it with lighter fuel (anyone that contains xylene), and apply it with finger or brush, let dry and build up
b) Smooth the outer silicone layer rubbing it with an ice cube (!). This will make an smoother, reattachable flex mold. It is important that your flex mold reattaches neatly into your mother mold, in order to prevent warping. Another useful tip is to build up the hard back with gauze, casting the entire flex mold, instead of using a solid layer of plaster.

---------------------------------------

I'm still amazed at the level of detail in the molds and cast. It is really high-quality. Suffice it to say that the only difference between my master and cast is the bumpy, bubbled surface.

I believe it is worth it to keep on with this experiment.

Keep your fingers crossed. Now comes part two of the experiment!!!

Rafa

[John Howling Mouse]

The good thing is that positive/raised bumps on your cast parts (as caused by your bubble voids in the negative molds) are easier to fix than filling in a zillion tiny air bubble voids on a cast part.

Try to do this work in a tray with sides and completely fill plaster over all the silicone glove molds.  This will provide stability and storability/longevity.  Another tip is to use some "mold lugs" (aka "mold keys") to help keep your plaster mother mold correctly in position with the silicone inner glove mold.  Anything that does not have any undercuts will do nicely: some short lengths of wood dowel, hemispherical humps from half a marble or small blisterpack domes, etc.  This will keep things from shifting around.

Good luck and do be careful with the flammables, eh!

[ysi_maniac]

Reading this I fell so weak