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Collecting => Customs => Customizing Tips and Tricks => Topic started by: Joe on October 22, 2005, 09:46 AM

Title: RTV rubber
Post by: Joe on October 22, 2005, 09:46 AM
o.k. I dont know if theres already a topic about this but can someone give me a tutorial on rtv rubber molding.Need to cast a atte gunner head (20 times) and a fox helmet .
Title: Re: RTV rubber
Post by: magillafett on October 22, 2005, 09:58 AM
FFURG has just about anything you need to know about customs and making them. In fact, here's the link to exactly what you're asking:


http://www.ffurg.com/casting_and_molding/rtv_molds.htm
Title: Re: RTV rubber
Post by: Joe on October 22, 2005, 10:02 AM
I know i'm a member to ffurg too but sadly i'm a idiot with out pics.(with the big words like the and do lol)
Title: Re: RTV rubber
Post by: CHEWIE on October 22, 2005, 11:28 AM
Have you done any sort of google search?  I have no idea how you would go about this either.

 :P
Title: Re: RTV rubber
Post by: Joe on October 22, 2005, 12:24 PM
not much (sueful) stuff comes up.I'll just go down to home deopt and ask someone.need to go there to get the rtv,resin,and a sharp blade for that dang foamcore.
Title: Re: RTV rubber
Post by: Delaton on October 22, 2005, 09:11 PM
NoMercyJoe, you can get RTV rubber at: POLYTEK (http://www.polytek.com/)

I use Platsil 71-20 1:1 ratio Silcone RTV rubber.  Home Depot won't know what the heck you're talking about.  The RTV rubber runs about $40 shipped for a trial size.  They usually give a 1/2 your first trial of any new product.
Title: Re: RTV rubber
Post by: Ryan on October 22, 2005, 10:05 PM
I get mine from http://www.hobbycast.net/ They were giving away a free DVD tutorial awhile back, I'm not sure if it is still going on.
Title: Re: RTV rubber
Post by: Joe on October 24, 2005, 05:14 PM
true,they said go to michaels.anyone know where to get on in a store.(would michaels work?)(anyone think michaels would have the supplies foe a simple latex cast)
Title: Re: RTV rubber
Post by: Smartypants1635 on October 24, 2005, 06:22 PM
i dont know but i got my latex rubber from hobbytown USA
Title: Re: RTV rubber
Post by: Ryan on October 24, 2005, 07:00 PM
Micheal's won't work. Speciallty stores like Hobbytown USA woulpd be better. But your best bet is to order online at either the site delaton or I suggested.
Title: Re: RTV rubber
Post by: Joe on October 24, 2005, 08:12 PM
on the site Ryan gave me,do i have to buy all that fancy smancy wax and mold realser to brush on hte wood before mold making?
Title: Re: RTV rubber
Post by: Ryan on October 24, 2005, 09:06 PM
Not if you don't need it, no. I buy the Hobby mold 160. And bought a pattern release spray for 2 part molds. Wax is for sculpting and recasting existing pieces to sculpt. the mold release is uneccessary, if you are just casting plastic figure parts you won't need it because plastic isn't porus enough. if you feel you need a release agent you can but that stuff, but a light dusting of talc powder will work just as well.
Title: Re: RTV rubber
Post by: Glassman6 on October 26, 2005, 03:12 PM
I use smooth-on's Smooth Sil 920 and i have yet to use an releaser or anything else.
Its very durable.
Title: Re: RTV rubber
Post by: Joe on October 27, 2005, 07:00 PM
for now I figured I will try something a guy at micheals said (surprisingly) sculpy mold and some plaster of paris.
Title: Re: RTV rubber
Post by: Ryan on October 27, 2005, 07:29 PM
Sculpey molds won't hold up for 20 castings. And it is much harder to do a 2 part mold with sculpey.
Title: Re: RTV rubber
Post by: Delaton on October 28, 2005, 07:38 PM
Brushable Latex Rubber is available at Michael's stores in the adhesive & glue aisle.  Latex usually has to be 3 or 4 layers thick to be an effective mold and hold its shape.  I have to stress that if you're casting any part that must be cast through a small hole, demolding will most likely crush the cast because the latex will be too strong.
Title: Re: RTV rubber
Post by: Joe on October 28, 2005, 08:53 PM
o.k. well I decided to go with the rtv.....now where is it I can find it in a store around here?I know im hasty.
Title: Re: RTV rubber
Post by: Ryan on October 28, 2005, 10:18 PM
Like I said earlier, online will probably be your best bet.
Title: Re: RTV rubber
Post by: Delaton on October 28, 2005, 11:16 PM
Unless you have access to a Pearl AND happen to catch them while they actually have it in stock, you need to go online.  Pearl carries Smooth-On in their stores but they only order it one case or so at a time.  When they run out, it could be weeks for a new shipment.  To add to it, Pearl doesn't list it online.

www.smoothon.com
www.polytek.com

Those are my suggestions.
Title: Re: RTV rubber
Post by: Joe on October 30, 2005, 11:53 AM
PEARL-its a store right?Is there one in MA (delaton im pointing your way){prefebly near saugus}
Title: Re: RTV rubber
Post by: Delaton on October 30, 2005, 06:59 PM
Yes, near Boston.  The Pearl stores I used to get my supplies at were in NJ.  A friend used to buy them out for both of us from time to time.
Title: Re: RTV rubber
Post by: RollaJedi on June 19, 2006, 02:42 PM
Ok, I'm gettin pretty frustrated.  For a 2 part mold, I put the master into the rtv mix trying to make it about half way in.  I do this after it has firmed up a little so it doesnt sink (about a couple minutes).  But, when I'm done with this step and come back to it for the top part of my mold, it has sunk down further into the stuff, sometimes burying parts!  SO, I usually have a really shallow indention in my top mold layer.  Any suggestions?
Title: Re: RTV rubber
Post by: Glassman6 on June 19, 2006, 04:17 PM
I wait 10 minutes before i place the pieces in.
When i pour, i take a spoon and rub it into the crevases of the side thats going face down.
SO when i stick it in 10 minutes later I dont have to worrry about RTV getting into the tiny places and
making airbubbles.
By this time you are pretty much pusing it in. SO you can stop when its as deep as you want it.

Another trick, is get a piece of scotch tape. long enough to run across your mold box.
and let the tape hold the piece from sinking all the way.

Title: Re: RTV rubber
Post by: RollaJedi on June 19, 2006, 04:30 PM
cool!  That should really help!  Your idea on the casting you commented on (not thick enough and dripping out before it was flipped) worked well too, just to let ya know.  :)  Thanks!
Title: Re: RTV rubber
Post by: Smartypants1635 on June 19, 2006, 05:43 PM
I got a perfect cast from a 2 part mold yesterday, sadly I went back and revised my sculpt. So I'm making a new mold as we speak.
Title: Re: RTV rubber
Post by: RollaJedi on June 20, 2006, 10:53 AM
ok, I waited 10 minutes last night and it still was goopy, so I waited some more.  I waited a total of about 30 minutes and it wasnt much better, so I stuck the stuff in there.  Naturally, it sank 3/4 of the way in some places.

Will the molds still work if they are like this?  If the top half is just a little indention of where the part jutted out some, can I still put casting stuff in there to make the cast?
Title: Re: RTV rubber
Post by: Smartypants1635 on June 20, 2006, 12:47 PM
yeah, that happens to me all the time. Still works.
Title: Re: RTV rubber
Post by: Glassman6 on June 20, 2006, 03:24 PM
Yes it will still work. If you get a line across the piece, it just wont be down the middle.
I have quite a few molds with pieces that went 3/4 of the way in.
Title: Re: RTV rubber
Post by: bikeridetony on August 13, 2007, 02:56 AM
Hi there,

I really need to make some molds for some Kubricks.  If you haven't heard of them, they're rare collectible Japanese figures.  I really only need the hair piece done which is one small piece.  Is there anyway I can pay you to do these?  I'll need about 40 in the end.  Let me know if you are interested or know anyone who's good and willing .  Thanks!

Tony
Title: Re: RTV rubber
Post by: Straxus on August 14, 2007, 07:37 AM
For those making two part molds for helmets this tutorial will help.
Now the tutorial is not on making molds for helmets specificly, but will help give ideas.
Dan Perez Studios molding and casting tutorials (http://www.danperezstudios.com/workshoppages/molding_casting.htm)

If you dont have a pressure pot, just use the air vents ideas mentioned in the tutorial using toothpics glued to small areas to allow air to squeeze out.

Depending on the RTV rubber used, sometimes before pouring the mold, use a old paint brush to make sure small crevaces are filled with mold material and air bubbles on the surface are removed before pouring. I found with my helmet casts this saves alot of hassles and makes sure molds work great first time arround. (This again is for those who dont have a pressure pot.)

Also a technique to use if making latex molds of head casts, make small cuts with an exacto knife in the location of the nose, chin, ears or any other part that might suffer air bubble problems. Make sure it is a small clean cut with a sharp exacto. When pouring casting resin it helps push the air bubbles out, and if its a small incision the casting resin should not leak out. I have been doing this for a while with alot of success.

As someone who has been using Rubber Urethane RTV for the last year, who has now started using silicone rubber, honestly, save the hassle and be patient and get the right stuff for the job. I am a horribly impatient person. I went the route of getting anything I could to start molding and casting right away and it was not only way more expensive in the long run but caused far far more frustration than it was worth. Check out Smooth-Ons distributer links. In many cases there is a company that can ship the stuff faster and cheaper than ordering it directly from the store. (Or the other mold making companies mentioned in this thread.)
Though if you MUST have something right away, another store you can check and see if its in your area is TAP plastics. Its not the greatest, but its out there. Their casting resin sucks for anything other than prototype work.

Well enough of my rambling on the subject...  :P
Title: Re: RTV rubber
Post by: Glassman6 on August 16, 2007, 01:10 PM
I dont think i've ever had a smooth on order take longer than a week. I've gotten stuf in 3 day before. You can pay for expidited shipping too, and get it next day. I've never had to do that and still gotten my orders very fast.
Title: Re: RTV rubber
Post by: BrentS on August 16, 2007, 04:11 PM
I dont think i've ever had a smooth on order take longer than a week. I've gotten stuf in 3 day before. You can pay for expidited shipping too, and get it next day. I've never had to do that and still gotten my orders very fast.

I'm with Glassman on this.  Smooth On always arrives very promptly and well packaged.
Title: Re: RTV rubber
Post by: Glassman6 on August 21, 2007, 07:23 PM
I needed some more supplies, I ordered Saturday evening and had my stuff sitting on my doorstep when i got home from work today (tuesday) .  Like i said, its not usually a long wait.
Title: Re: RTV rubber
Post by: Ruprecht on August 22, 2007, 12:57 AM
You guys must be east of the Mississippi, because it takes over a week for anybody (smooth-on, polytek, micro-mark) to get any supplies to me.  Sometimes 2.
Title: Re: RTV rubber
Post by: Straxus on August 22, 2007, 10:46 AM
I just got my order, but my smooth-on distributer is in Washington and I am in Oregon. I ordered on thursday and got the stuff on monday. When I origionaly was going to order from Smooth-On they suggested I go though the Washington distributer to get my stuff faster and cheaper shipping.
Ruprecht, where are you located? There might be a closer distributer to you.