casting crystal clear 200 woes

davidlgreen · Post by **davidlgreen** » Mon May 12, 2008 6:28 am

i recently purchased some crystal clear 200 casting resin and am casing it in
in aeromarine 25 rtv .the cc200 says 16 hour cure time, but it still comes out of the mold quite sticky and droopy. am i doing something wrong?
should i try a different clear resin? help me obi-wan konobi, you're my only hope.

modelnutz · Post by **modelnutz** » Mon May 12, 2008 7:03 am

Best advise I can give.....

Heat the molds in a low oven for half hour.....
Warm the seperate components of the resin as well....not super hot...just warm

Mix the resin compoments..and get it in to the mold and under pressure quickly.

One bonus to this technique is the thinning effect on the resin...

USS Atlantis · Post by **USS Atlantis** » Mon May 12, 2008 7:07 am

I also had issues with Crystal Clear and moved to Castin' Crafts Clear resin, this can be had from Dick Blick

http://www.dickblick.com/zz335/20/

Ed's suggestion of warming the mold and components is good for any clear resin

Also a post-cast bake of 150 degrees for 45-60 minutes can help the setup

Atlantis

Chacal · Post by **Chacal** » Mon May 12, 2008 5:54 pm

How thick is the casting?

What cures the resin is the heat produced by the catalyst. If you have a part which is too thin, the will not be enough heat buildup to cure the resin all the way through. Conversely, if you have a massive, solid part to cast, it may overheat and crack as the heat built up is excessive.

Your problem seems to be too little heat, hence the suggestions given by the fellas above.

I personally prefer resin with a separate catalyst, in ratios of 100:1 like I have down here in Rio. This way, I can vary the ratio to accommodate for the 'bulk' of the cast.

The crystal clear 200 series is a water clear, UV-protected, hard (80 D) low-viscosity casting urethane: CC200 (cast to 3" thick, cures in 16 hrs), CC202 (cast to 0.5" thick, cures in 90 min), CC204 (cast to 6" thick, cures in 48 hr) and CC206 (cast in excess of 6", cures in 48 hr). The mix ratio is a convenient 1:1 by volume and the mixed viscosity is very low.

The varying series and thicknesses and times are there because the product is a 1:1 ratio mix, so for different thicknesses, you have different 'heat' levels (lower for thicker casts), with a corresponding higher cure time, to allow for a gentler cure (without cracking). Thus, if your part is thinner than 3", it won't cure properly. If that's the case, go with CC202, which is 'hotter' and can cure in thicknesses as low as 1/2 inch (in just 90min!)

davidlgreen · Post by **davidlgreen** » Tue May 13, 2008 5:58 am

the casting is a as small cylindical object about 1/8th in dia. and about 3.5 in
long. will definitely try the mold heating but the other resin recommended is polyester,right? and i'll probably try that, but isn't that stuf really,really stinky?

USS Atlantis · Post by **USS Atlantis** » Tue May 13, 2008 6:39 am

davidlgreen wrote:the casting is a as small cylindical object about 1/8th in dia. and about 3.5 in
long. will definitely try the mold heating but the other resin recommended is polyester,right? and i'll probably try that, but isn't that stuf really,really stinky?

I haven't noticed anything more that you'd get from Mineral Spirits or Thinner - but yes, it is a little more 'smelly' than other resins

And with a piece this small, definitely pre-heat the mold, the resin components and do a post-cast bake - I do all that even with the Castin' Craft for smaller parts

Atlantis

DasPhule · Post by **DasPhule** » Tue May 13, 2008 7:47 am

As it says on the can, Smooth On Crystal Clear 200's mix is 100 side A to 90 side B by weight, not 1 to 1. ALL of the Crystal Clear series resins are 100 to 90 mix. Mix them 1 to 1 and you will always get sticky casts that will remain sticky for a very long time, sometimes forever.

It's VERY sensitive, the mix ratio has to be almost perfect, but if mixed correctly it always comes out nice. The flash will be gooey, the parts will be a little soft, but over a couple of days time they'll harden. Post baking speeds up this process considerably.

Erin
<*>

davidlgreen · Post by **davidlgreen** » Wed May 14, 2008 6:02 am

you mean i've got READ the instructions? well i'll weigh it out next time.
anyway also ordered some cc 202 got my pressure pot special from harbor freight, any particular brand of dye you guys like? i am making some engines for my leif ericson style cargo ship. thanks dave

Stu Pidasso · Post by **Stu Pidasso** » Wed May 14, 2008 9:19 pm

So should you post bake the cast right in the molds(pour, clamp, wait, throw the whole thing in the oven) or pull the parts, then put them on a cookie sheet or sumpin, and then bake them by themselves?

USS Atlantis · Post by **USS Atlantis** » Thu May 15, 2008 5:23 am

Stu Pidasso wrote:So should you post bake the cast right in the molds(pour, clamp, wait, throw the whole thing in the oven) or pull the parts, then put them on a cookie sheet or sumpin, and then bake them by themselves?

I've done both with the Castin' Craft product; it probably doesn't hurt the casting to do both with the Smooth-On either

Atlantis

davidlgreen · Post by **davidlgreen** » Thu May 15, 2008 5:28 am

my can of 200definitely says 1:1 by volume but the 202 says 100:90 by weight. im sooo confused.

USS Atlantis · Post by **USS Atlantis** » Thu May 15, 2008 6:31 am

davidlgreen wrote:my can of 200definitely says 1:1 by volume but the 202 says 100:90 by weight. im sooo confused.

All the Crystal Clears are 1:1 by volume; 100:90 by weight - the Part B is more dense than the Part A which is how that difference occurs

Best bet is to use a small scale to insure proper weight ratio mixing - a 1 pound scale you can get at Target/K-Mart/Wally World in the kitchen section is relatively inexpensive and good enough.

Atlantis

Stu Pidasso · Post by **Stu Pidasso** » Thu May 15, 2008 9:29 am

SCC-7107 USS Atlantis wrote: I've done both with the Castin' Craft product; it probably doesn't hurt the casting to do both with the Smooth-On either

I'm more worried about the molds...

macfrank · Post by **macfrank** » Thu May 15, 2008 12:29 pm

Stu Pidasso wrote:
I'm more worried about the molds... :D

Why? I've baked RTV molds up to 200F with no problems. The 120 - 150F shouldn't be an issue for most mold materials. When I've cast clear parts, I leave them in the mold when they bake - less chance of them sticking to a sheet or warping.

USS Atlantis · Post by **USS Atlantis** » Thu May 15, 2008 3:08 pm

macfrank wrote:
Stu Pidasso wrote:
I'm more worried about the molds...
Why? I've baked RTV molds up to 200F with no problems. The 120 - 150F shouldn't be an issue for most mold materials. When I've cast clear parts, I leave them in the mold when they bake - less chance of them sticking to a sheet or warping.

I've had no issues baking the cast in the mold - and that's true weither it's an Alumilite or Oomoo mold

The lower temps that we're advocating for baking the cast should have no effect on the mold material

Atlantis

davidlgreen · Post by **davidlgreen** » Mon Jun 02, 2008 6:34 am

thanks for all the help. i bought some 202 heated the molds, put it in my newly acquired harbor freight pressure pot and it came out perfectly!
got some pics of what i casteded, will post them later this week.

vaderman · Post by **vaderman** » Sun Jun 15, 2008 11:57 am

Heating the molds is a must with CC. One question is, do you need absoulute clear parts (for which you should be pressure casting) or do you need translucent? Are you pigmenting the parts (adding color). If so, you can use Smooth On color match 325. When pressure cast it is very translucent. Not crystal clear but great for translucent parts.

Scott

Starship Modeler Discussion Forums

casting crystal clear 200 woes

casting crystal clear 200 woes

thickness of casting

Re: thickness of casting

ah crap

crystal clear mix

Re: crystal clear mix

got me some cc 202