Trains.com

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Anybody want to dish about Hydrocal?

1887 views
17 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    February 2021
  • 749 posts
Anybody want to dish about Hydrocal?
Posted by crossthedog on Tuesday, June 28, 2022 8:23 PM

I'm starting to see this word a lot. Hydrocal. Like in Downtown Deco's structure kits and other places I'm rummaging around in, and someone just mentioned modeling with it here in recent post.

I looked it up quickly and there's a photo on Amazon that looks like a pile of baking flour on a countertop. Not much of a clue there about what its advantages are, why I would want a model kit made out of it, or what the gotchas are.

Do you have any exerience with it? Or even an educated or uneducated opinion about it? What's it good fer? Why Hydrocal?

Thanks in advance.

-Matt

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 20,716 posts
Posted by MisterBeasley on Tuesday, June 28, 2022 9:43 PM

It's a casting plaster, similar to Plaster of Paris.  I think it's a bit finer scale and castings come out harder and a bit lighter in weight.

I've done a lot of Hydrocal casting over the years, mostly stone or rock walls.  I have found that, by timing it carefully, I can actually bend a partially set casting to get a curved wall.

You can add dyes to the unset Hydrocal to color the casting, or you can paint it with a spray or wash to get the desired color.

I have used liquid latex rubber to create molds which I then use to "clone" stone items like tunnel portals or create concrete platforms for train stations.

This subway station was scratchbuilt usimg a lot of Hydrocal.  The platforms were made from a styrene sheet, and the walls from a similar sheet with smaller squares.  To get the curved columns, I covered the plaster part of the setting mold just before it solidiied and wrapped it around a piece of 1x2 wood.

This above-ground trolley station was made by using latex rubber to make a casting mold from a section of artificial honeycomb.  I then filled the mold with Hydrocal.

Here is a section of cut stone wall fom a commercial mold.  As it was setting, I curved it around a section of pink foam to get the curvature, then let it set.

The last one above is part of the turntable wall for my pit-bashed Atlas turntable which I sunk below the table.

It takes an iron man to play with a toy iron horse. 

  • Member since
    January 2004
  • From: Canada, eh?
  • 13,016 posts
Posted by doctorwayne on Tuesday, June 28, 2022 10:41 PM

I've used both Hydrocal and Dental plaster for casting, but both set too fast for my way of working.
I switched to Durabond 90, a patching plaster which sets in about 90 minutes (there are other versions that set faster, also with relative numbers following the brand name). 
The setting will occur pretty-well, no matter how much (or how little) water is used, and once set, it's extremely strong and durable.

I use it over aluminum screen to create landforms...

...and in homemade moulds for casting the support piers for bridges...

...and it also works well for making "water"...

Wayne

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 16,534 posts
Posted by SeeYou190 on Wednesday, June 29, 2022 12:13 AM

I experimented with Hydrocal when I built the Layout Test Segment section.

The only advantage I have found is that it can be ground with a coarse sander when it is fully dry. That is not much of an advantage.

I have used Plaster Of Paris on all previous layout with never any problems. 

My intention is to use Plaster Of Paris on the next layout too. It is easy to get, and I know it works well.

-Kevin

Living the dream and happily modeling my STRATTON AND GILLETTE Railroad in HO scale. The SGRR is a freelanced Class A railroad as it would have appeared on Tuesday, August 3rd, 1954, in my personal fantasy world of plausible nonsense.

  • Member since
    February 2021
  • 749 posts
Posted by crossthedog on Wednesday, June 29, 2022 1:09 AM

Everyone so far has mentioned this as a medium that you can cast and mold with, the way I did with a big tub o' Plaster of Paris when I was a kid. But I keep seeing products made of Hydrocal, like the Downtown Deco kits. So those kits are basically plaster castings? Wouldn't they be likely to chip and flake? The main reason I'm interested in this stuff is for structure kits.

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

  • Member since
    August 2006
  • 1,475 posts
Posted by trainnut1250 on Wednesday, June 29, 2022 1:47 AM

Matt,

Opinion from someone who has used lots of hydrocal (many bags)....Yes, the castings can chip but I haven’t found it to be a big problem. Hydrocal is very strong and that is one of its advantages.

There are several kit makers using hydrocal/plaster castings. Yorke were/are the preferred plaster kits in my neck of the woods. There is very little chipping/flaking if you are reasonably careful with the assembly.

In general, I consider hydrocal to be one the Cadillacs of plasters. I love the creamy nature of hydrocal and I like the strength of the cured plaster. The only drawback, as Wayne states, is the speed of the set (can be too fast for some situations). I’m sure that casting plaster might work just as well but the hydrocal just has that certain richness to it.

FYI: “hydrocal light” is not the same as regular hydrocal

Opinions will vary,

 

Guy

see stuff at: the Willoughby Line Site

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 16,534 posts
Posted by SeeYou190 on Wednesday, June 29, 2022 8:24 AM

crossthedog
But I keep seeing products made of Hydrocal, like the Downtown Deco kits. So those kits are basically plaster castings? Wouldn't they be likely to chip and flake? The main reason I'm interested in this stuff is for structure kits.

I have built a handful of Downtown Deco kits. I love the way they take paint, and I have never had a problem with chipping or flaking.

For wargaming, we have built tons of plaster structures using hydrocal plaster and Hirst Arts molds. Hydrocal casts very easily and we have never had problems with durability.

-Kevin

Living the dream and happily modeling my STRATTON AND GILLETTE Railroad in HO scale. The SGRR is a freelanced Class A railroad as it would have appeared on Tuesday, August 3rd, 1954, in my personal fantasy world of plausible nonsense.

  • Member since
    July 2006
  • From: west coast
  • 7,216 posts
Posted by rrebell on Wednesday, June 29, 2022 9:33 AM

Can not be beat for rock castings and if you do them thin with a backing the cracks you get are as relistic as you can get.

  • Member since
    January 2019
  • 2,103 posts
Posted by John-NYBW on Wednesday, June 29, 2022 9:41 AM

I've read that it is harder than Plaster of Paris but I've used both and haven't noticed much difference. Plaster of Paris is more readily available so that's what I go with.

  • Member since
    February 2001
  • From: Wyoming, where men are men, and sheep are nervous!
  • 3,219 posts
Posted by Pruitt on Wednesday, June 29, 2022 9:47 PM

I'm using Hydrocal over plaster cloth and for rock molds in my version of the Wind River Canyon in Wyoming. Hydrocal is much stronger than Plaster of Paris, and is lighter. A thin layer has strengthened my canyon walls significantly ( the colored part is Hydrocal):

It also makes very strong molds. I cut the top of this casting to reconfigure the wall above a bit. Took me half an hour to cut through a 1/4" thick casting!

It holds mold detail very well, and is very resistant to chipping and flaking. I'm very pleased with it's physical properties.

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 20,716 posts
Posted by MisterBeasley on Thursday, June 30, 2022 1:56 PM

I bought a cheap razor saw at Michaels.  It has two blades.  I save one for trimming plastic scratchbuilding parts, and the other is for Hydrocal.  The razor saw works great on Hydrocal.

It takes an iron man to play with a toy iron horse. 

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 16,534 posts
Posted by SeeYou190 on Saturday, July 2, 2022 2:50 AM

Pruitt
I cut the top of this casting to reconfigure the wall above a bit. Took me half an hour to cut through a 1/4" thick casting!

You need one of these bad boys:

-Photograph by Kevin Parson

I can't imagine life without one.

-Kevin

Living the dream and happily modeling my STRATTON AND GILLETTE Railroad in HO scale. The SGRR is a freelanced Class A railroad as it would have appeared on Tuesday, August 3rd, 1954, in my personal fantasy world of plausible nonsense.

  • Member since
    July 2006
  • From: west coast
  • 7,216 posts
Posted by rrebell on Saturday, July 2, 2022 8:28 AM

John-NYBW

I've read that it is harder than Plaster of Paris but I've used both and haven't noticed much difference. Plaster of Paris is more readily available so that's what I go with.

 

Then you did not mix it right. Wrong mixture or way you mix it can make it soft, did that once or twice. Also it takes longer to fully cure.

  • Member since
    February 2001
  • From: Wyoming, where men are men, and sheep are nervous!
  • 3,219 posts
Posted by Pruitt on Saturday, July 2, 2022 8:43 AM

SeeYou190
 
Pruitt
I cut the top of this casting to reconfigure the wall above a bit. Took me half an hour to cut through a 1/4" thick casting!

-Photograph by Kevin Parson

I can't imagine life without one.

-Kevin

Got one. I didn't want to throw a lot of plaster dust all over the area (that's my excuse for not thinking of it at the time).

  • Member since
    February 2021
  • 749 posts
Posted by crossthedog on Saturday, July 2, 2022 10:16 AM

SeeYou190
You need one of these bad boys: -Photograph by Kevin Parson I can't imagine life without one.

What is that, like a one-handed Sawzall?

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

  • Member since
    January 2009
  • From: Maryland
  • 11,997 posts
Posted by ATLANTIC CENTRAL on Saturday, July 2, 2022 11:38 AM

crossthedog

 

 
SeeYou190
You need one of these bad boys: -Photograph by Kevin Parson I can't imagine life without one.

 

What is that, like a one-handed Sawzall?

 

 

Where have you been? That is one of the most important construction/remodeling advancements in the last 15 years.

This was the first one - now everybody makes them:

https://www.toolstoday.com/v-17616-72297261090.html?glCountry=US&glCurrency=USD&ne_ppc_id=10371521939&gclid=CjwKCAjw2f-VBhAsEiwAO4lNeMR4g1u-hipsxqB4gbdUha4B17IOJaPWrEb8VGwDP3rUG-uuaP-0tBoC5jwQAvD_BwE

It is not brutal like a sawzall, it is a tool that can to careful remodleing demo, or more demanding heavy work.

After having the original for years, i now perfer this one:

https://www.homedepot.com/p/DEWALT-20-Volt-MAX-XR-Cordless-Brushless-3-Speed-Oscillating-Multi-Tool-Tool-Only-DCS356B/309250506?g_store=&source=shoppingads&locale=en-US&&mtc=SHOPPING-RM-RMP-GGL-D25T-025_009_PORT_POWER-NA-DEWALT-NA-SMART-na-NA-MK57954-111111111-BT3-3359-NA-NA-NA&cm_mmc=SHOPPING-RM-RMP-GGL-D25T-025_009_PORT_POWER-NA-DEWALT-NA-SMART-na-NA-MK57954-111111111-BT3-3359-NA-NA-NA-71700000096147030-58700007869563731-92700071440031932&gclid=CjwKCAjw2f-VBhAsEiwAO4lNeG6fvnoE21AnNorZLK5yx536SOIWY9nRB4SlTqF3lSI6ZwOo3qBYHBoCDg4QAvD_BwE&gclsrc=aw.ds

As for hydrocal, we used it in the the 70's to make model layout scenery with very minimal support, no wire mesh, just a few wood uprights here and there, and attached to the roadbed of open grid construction.

Google "hard shell scenery"

Often people just balled up newspaper to support it, then pulled the newspaper out from underneath after it cured.

I plan to to use wire screen and Durabond 90 on my new layout, it dries slower and is easier to work with,  but still really strong. 

Sheldon

    

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 16,534 posts
Posted by SeeYou190 on Saturday, July 2, 2022 11:43 AM

DOUBLE POST

SORRY

-Kevin

Living the dream and happily modeling my STRATTON AND GILLETTE Railroad in HO scale. The SGRR is a freelanced Class A railroad as it would have appeared on Tuesday, August 3rd, 1954, in my personal fantasy world of plausible nonsense.

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 16,534 posts
Posted by SeeYou190 on Saturday, July 2, 2022 11:44 AM

Pruitt
I didn't want to throw a lot of plaster dust all over the area (that's my excuse for not thinking of it at the time).

Sounds like a good reason to me. It will kick up lots of fine dust.

crossthedog
What is that, like a one-handed Sawzall?

Not really. I think the common term for that tool is an "Oscillating Multi-Tool". It just vibrates the end back and forth about 1/16" or so, and can do all kinds of things.

I use mine for grout removal and flush-trimming of trim pieces. It also has a detail sander attachment, but mine is a bit heavy to use for sanding.

-Kevin

Living the dream and happily modeling my STRATTON AND GILLETTE Railroad in HO scale. The SGRR is a freelanced Class A railroad as it would have appeared on Tuesday, August 3rd, 1954, in my personal fantasy world of plausible nonsense.

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!