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Sculptamold

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Sculptamold
Posted by BigDaddy on Tuesday, July 03, 2018 7:28 PM

I had an older thread on molds 

http://cs.trains.com/mrr/f/88/t/270383.aspx

But it might be time to start a new thread as I ran into a unexpected glitch.  I am creating scenery under a bridge and adding moldings of scuptamold.  The right bridge pier will go on the far right.

Sculptamold contracts a little as it hardens.   What I thought was going to be a rough, level surface; ideal for a little pond or creek, ended up being a surface with depressions, not ripples. So it needed sanding, not a big deal.

I used less water in this mix than my test casting and thought it would dry quickly.

When I tried sanding it today, 3 days after applying, it was not full cured and some of it rolled up into little cylinders, like sanding wet paper and it felt cold a bit like soft sticky fudge.  It is in the basement, which is humid and cool. 

A heat gun gets too hot for the foam, so I tried a hair dryer, and it stayed cool and damp for longer than I would have thought.  I will try turning up the room dehumidifier. 

The tan color is where I plan to add water

Henry

COB Potomac & Northern

By the Chesapeake Bay

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Posted by Track fiddler on Tuesday, July 03, 2018 7:52 PM

Looking good Henry.... do you like working with sculptamold better than plaster?

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Posted by BigDaddy on Tuesday, July 03, 2018 8:43 PM

Plaster:

  • More dust when you mix it.
  • Drips of liquid plaster get on the floor and the scenery
  • Dries predictably and strong.  So far, in my experience, it dries quicker.
  • Heavy

Sculptamold

  • Much lighter.
  • It looks like a clump of attic insullation, and is a little bit fiberous when you mix it, as opposed to powdery plaster.
  • I'm using in in a fairly soft state and taking the mold off earlier than I would with plaster.  At that point, you need to coax it to lie on foam and come out of the mold.  I don't know if letting it dry longer before applying it would change that. It is easily manuevered to fill in gaps and lie flat.
  • Prone to forming holes in the casting.  Not sure why I am having that problem.  When wet, you can push it around and fill the holes or gaps between the castings, but clearly I missed some of the holes. 
  • With both plaster and sculptamold, you can rub it in gaps or holes in the underlying scenery.
  • Even though I am using wet water, it can form strands as I pull off the mold. A pallette knife can fix those.
  • The slow drying I am experiencing is a negative.

I think it will be less messy to sand than plaster, but that remains to be seen.

Both can be carved before they set up.  The latest Rons' Trains and Things youtube video shows him making a plaster cast.  He lets it get pretty hard then glues it on, I never did that.  My technique for the sculptamold comes from MRVP's Canadian Canyon.

Stay tuned and I'm sure I'll have more opinions as I work with it.  What you see has been colored by craft paints, brown and gray.

 

Henry

COB Potomac & Northern

By the Chesapeake Bay

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Posted by j. c. on Tuesday, July 03, 2018 9:06 PM

never having used or for that matter seen it , is this sculpamold like the paper mache of 50 years ago ? 

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Posted by bogp40 on Wednesday, July 04, 2018 7:40 AM

Sculpamold does has it's use and advantages, however, for that flat base Hydrocal would have been a better choice.

Modeling B&O- Chessie  Bob K.  www.ssmrc.org

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Posted by dknelson on Wednesday, July 04, 2018 10:24 AM

BigDaddy
What I thought was going to be a rough, level surface; ideal for a little pond or creek, ended up being a surface with depressions, not ripples.

Yes I notice the difference in working with Sculptamold in winter when the furnace is on versus summer when my basement is cool and humid even with a dehumidifier going.  It takes a while to really dry and cure.  It even smells a little.

A few things.  First that irregular surface is not entirely unlike what the bed of a body of water looks like, so maybe sanding it smooth is not called for. 

Second, I "scenic" my creek, river, pond and lake beds with Woodland Scenics green ground foam to similate "seaweed" and algae, bits of sticks for waterlogged logs, rocks, and various other stuff that finds its way to the bottom.  Do that and I think you'd notice the surface irregularities less.  For the actual water I like the Magic Water product but there are other good choices out there.

Third, if you really want a smoother bottom surface -- rather than sanding the sculptamold down, I'd get a little spackling compound or Durham's Water Putty, or even brush on some white glue, and fill up the depressions.

Dave Nelson

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Posted by Schuylkill and Susquehanna on Wednesday, July 04, 2018 10:50 AM

The drying time of Sculptamold is heavily dependent on the temperature and relative humidity.  I'd suggest getting a dehumidifier and mabye a space heater.  Your layout will be a lot happier, too!  Pilling is always a problem when trying to sand or shape mostly-dry Sculptamold - wetting the surface can allow for some hand-smoothing, but there's not much that can be done to make it sandable except wait until it's fully cured.

I've noticed the contraction issue, too.  When looking to make a level surface, I always pour plaster.  The edges then get blended into the surrounding terrain using Sculptamold or ground goop.  When building a tiered water feature, Sculptamold can be used to create little dams to hold back the pours, but I wouldn't use it for the entire surface.

I've been having pretty good luck with my home-made Sculptamold.  I dump some water and cut-up newspapers into a cheap vegetable chopper (like this $9 one from Walmart) and turn it into a wet paper mulch.  Add some Plaster of Paris and a little more water, and vualá, instant Sculptamold.

 

Modeling the Pennsy and loving it!

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Posted by BigDaddy on Wednesday, July 04, 2018 7:17 PM

I now see the fine print says it may take several days to cure.  My test piece was made upstairs, not in the basement so it is dry.  I can dent it with a fingernail, if I press really hard, but it does not pill if I sand it.

It's been 50 years since I messed with paper maiche and I really can't remember to compare the two.  I does act like there is some plaster mixed in with it.

I did crank up the dehumidifier.  As it was 100 degrees yesterday, I am not buying a space heater to run in the summertime. 

I am in no rush and haven't decided what I am going to use for water.  It's a very small area so buying a Woodland Scenics deep pour water kit, would be a waste.

Henry

COB Potomac & Northern

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Posted by SeeYou190 on Wednesday, July 04, 2018 8:12 PM

I use Sculptamold for rocks and for the last layer of scenery forms, just blending everything together. I love it.

.

I have never actually used it for casting.

.

The thickness of the Sculptamold greatly increases the setting/curing time also.

.

-Kevin

.

Happily modeling the STRATTON & GILLETTE RAILROAD located in a world of plausible nonsense set in August, 1954.

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Posted by Track fiddler on Wednesday, July 04, 2018 9:14 PM

bogp40

Sculpamold does has it's use and advantages, however, for that flat base Hydrocal would have been a better choice.

 

Bob  thanks for jogging my memory. I was trying to recall and think of hydrocal when this thread first came out.

I did a lot of research when I got back into this hobby. I remember reading how hydrocal is a great alternative to plaster. It's lighter, easy to work with, has a little more working time, also more durable they say.

Henry I still say what you've done looks great. The picture of the nice work you did definitely deserves the chance to dry.

I will have to agree with Bob's suggestion if what I've read of hydrocal is true. I'm definitely going to try it when the time comes.

 

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Posted by mlehman on Friday, July 06, 2018 5:53 AM

BigDaddy

Plaster: MDries predictably and strong. So far, in my experience, it dries quicker.

Heavy Sculptamold

SNIP

I'm using in in a fairly soft state and taking the mold off earlier than I would with plaster. SNIP  The slow drying I am experiencing is a negative.

Best way to avoid this is to use less water with the Sculptamold.

When mixing plaster, you have to stick to the formula pretty closely or the reaction won't cause it to set right.

With Sculptamold, the formula is much more flexible. Yes, wetter will help a little with filling voids, but try mixing longer, more throughly and that should help.

Another possiioity is to use wetter Sculptamold to line the mold, then pack in a drier mix to fill it.

Beyond the relatively minimal amount of water needed oi get the Sculptamold to set up, its mostly a matter of adding just enough more to facilitate it's use. If that's too wet for some reason, try using less water.

Mike Lehman

Urbana, IL

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Posted by gary233 on Friday, July 06, 2018 6:08 AM

BigDaddy

I had an older thread on molds 

http://cs.trains.com/mrr/f/88/t/270383.aspx

But it might be time to start a new thread as I ran into a unexpected glitch.  I am creating scenery under a bridge and adding moldings of scuptamold.  The right bridge pier will go on the far right.

Sculptamold contracts a little as it hardens.   What I thought was going to be a rough, level surface; ideal for a little pond or creek, ended up being a surface with depressions, not ripples. So it needed sanding, not a big deal.

I used less water in this mix than my test casting and thought it would dry quickly.

When I tried sanding it today, 3 days after applying, it was not full cured and some of it rolled up into little cylinders, like sanding wet paper and it felt cold a bit like soft sticky fudge.  It is in the basement, which is humid and cool. 

A heat gun gets too hot for the foam, so I tried a hair dryer, and it stayed cool and damp for longer than I would have thought.  I will try turning up the room dehumidifier. 

The tan color is where I plan to add water

 

Looks very much like a dry lake bed

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Posted by BigDaddy on Friday, July 06, 2018 7:15 PM

It does look like Gary's dry lake bed.  Wasn't realling wanting a dry bed though.  I am enjoying the heck out of learning a new technique, even though there are some bumps in the road.  The amount of water in the mix certainly makes a difference as does the ambient temperature, humidity and thickness of the casting.

If I could drag the layout out into the sun, I'm sure it would dry in no time.  I did get brave today and leave the casting in the mold for longer than I ever dared.  It was a wet mix, but nothing stuck to the mold, and it was still workable to fill in adjoining gaps. 

The worst thing I could do is get out the heat gun and melt the underlying foam, so I am trying hard to resist that temptation. 

Stay tuned for painting

I can't wait to start painting, but I need to finish up all the castings first. 

Henry

COB Potomac & Northern

By the Chesapeake Bay

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Posted by BigDaddy on Monday, July 30, 2018 7:23 PM

Update on my progress

I am going to use matte medium for the water in the white spot in the photo.  I have been playing around with various craft paint colors. 

I am getting all my mistakes out of the way.  The last coat was with no color, and I thought it would dry clear.  So far it has not. The dark green is too dark.  The brown and light green are possibilities.

I got impatient and hit it with a heat gun and it blistered and trapped air bubbles popped.  The crescent is a collaped air bubble.

The major discoveries were it is not self leveling, it shrinks so it coats an uneven bottom, rather than fills the bottom and air bubbles are a problem, even without the heat gun.

It is slow to dry, so just letting it sit may get rid of the bubbles.  But it requires vigorous mixing to get a homogenous color.  With multiple pours, it approaches level, so I think that will ultimately work out too. 

I'm going to try simultaneous pours of slightly different colors to create a run off running into the main pond.

Henry

COB Potomac & Northern

By the Chesapeake Bay

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Posted by BigDaddy on Monday, July 30, 2018 7:50 PM

I was trying to get the inflow of a different color and wasn't worried about the green being too dark, here, but it overwhelmed the tan.  The run off isn't right, yet.  That's the point of practice.  For sure the green is too dark, besides a lighter green, maybe I need a 3rd color for the mixing.

I can poke at the bubbles with a toothpick.  The drying time is hours.

Henry

COB Potomac & Northern

By the Chesapeake Bay

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Posted by CRIP 4376 on Thursday, August 09, 2018 7:31 AM

I have used it a couple of times and plan to use it a lot after we move to our new house.  The easiest way for me to apply it was with a palette knife.  It was like putting frosting on a cake.  The base was plaster cloth and it was an easy application.  There was no problem with splitting or shrinking because the house has geothermal and the temperature and humidity do not change much.  The new house will have the same.

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Posted by Dennis S. - Central Rockies RR on Thursday, August 09, 2018 10:11 AM

Depending on what I am doing, I will mix other things with it. Try starting with your ground color latex, add water to the amount you intend to use. Then mix... and you will have colored sculptamold. To smooth it out, I add more plaster of paris or gysum lite for more small rocky 'texture.' Or even sand. 

But I almost always start with some latex paint and add water. This avoids those conspicuous white voids that you never see until you think you are all done. 

Dennis

Heap-Big Chief Engineer & COO

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