Hydrocal - pros and cons

Discussion in 'FAQs' started by northern_blues, Feb 24, 2005.

  1. northern_blues

    northern_blues New Member

    I'm building my first HO layout and I'm leaning towards a subroadbed of 2" foam over 1X3 joists at 12" o.c., all sittin on 3X3 L-girders.

    1) Will structures using hydrocal walls be a problem because of weight?

    2) After carving up the foam for scenery, if I finish the look with hydrocal for rock walls and even use hydrocal rocks from molds, is this too heavy for the foam bed?

    I like the look of some aged brick walls I've seen that were cast in hydrocal so I thought it would be a useful skill to pick up. :rolleyes:

    thanks, all

  2. Gary Pfeil

    Gary Pfeil Active Member

    I'm not speaking from experience, but it seems like you should have no problem!
  3. northern_blues

    northern_blues New Member


    Yeah, I was looking at C.C. Crow's stuff on his website and he makes these extraordinary brick walls, very realistic, among other things.

    I thought if I had a large manufacturing area, lots of old buildings, walls, etc., that the weight could add up.

    Plus, if hydrocall is a great medium to use, I could see making my own molds in the future.

    On the other hand, I'm not interested in making my benchwork any heavier to support this. The goal is a light and strong layout, both in benchwork and in scenery, while looking great!

    (Just like we all want......)

  4. interurban

    interurban Active Member

    I Use hydrocal all the time, one of our group Brian makes all the molds.
    It saves a LOT of money Dave.

    I agree with Gary. I don`t see a problem. :)
  5. northern_blues

    northern_blues New Member

    Chris, I'm in Aurora, couple km's up the 404 from you.

    Does Brian make what, rock molds and such? Is Hydrocal breakable or pretty solid? Do you use Hydrocal for building structures or just accessories, street debris, trackside stuff like barrels and tires, etc. or just for scenery like elevation changes, ponds, cliffsides, roads, stuff like that?

  6. interurban

    interurban Active Member

    Hi Dave , Brian makes molds from an original wall and bridge face.
    I use it for putting roads in also with streetcar track in the roads.
    River beds and ponds.
    I`ll email Brian this thread and he can tell you how he makes the molds.
    Chris. :thumb:
    See you soon Neighbore.
  7. Gary Pfeil

    Gary Pfeil Active Member

    You could check to allay any concerns by placing the 2" foam in place across the joists and placing say 10 lbs of weight between the joists and just letting it sit there a few days. I doubt you'll have a problem. I'll have to check out C.C. Crows stuff, it sounds nice.

  8. jim currie

    jim currie Active Member

    hydrocal is a dense plaster but in thin sections it will break been using it for casting walls and rocks for a long time unless you get carried away weight will not be a problem. also if you can get the green colored it is stronger and sets faster than white.
  9. northern_blues

    northern_blues New Member

    I was checking C.C.Crow's website again as he has an excellent reproduction of a NP Roundhouse Circa 1912. All hydrocal. He is recommending 3/4" ply as a base for this roundhouse!

    I may have to go ply in spots and use foam mostly for scenery.

  10. SAL Comet

    SAL Comet Member

    Dave, IMHO here's no way your going to use enough hydrocal on HO structures to cause a weight problem.
  11. Duckman

    Duckman Member

    Hi Gents, Bian here with some info about Hydrocal. It,s fairly strong when your work has had time to dry and harden,As for weight, it can get heavy but usually not a problem. I really think a sound benchwork is most important. I,d really hate to see an amazing railroad with years of hard work, built on a shakey foundation,It,s important to build it from the ground up the right way.This way weight is never really an issue. When using Hydrocal, Woodland Scenics sells Lite Weight Hydrocal in a milk carton at your local Hobbies Store. It cost a little more but it,s half the weight of original hydrocal and just as strong.I buy the original hydrocal in a 100 LB bag for aprox. $35.00 , Compare to a milk carton full for $12-$15.00 at the hobbies store, You do the math!!! I use it to make rocks , walls, abutments, roads, riverbeds and much more.I must go now to help one of my sons. I,ll get back to ya about making great molds, which saves you and your friends lot,s of money. Just ask Chris, He,s borrowed mine enough. Later Guys, Duckman.
  12. interurban

    interurban Active Member

    Just ask Chris, He,s borrowed mine enough. Later Guys, Duckman.[/QUOTE]
    :p :rolleyes: :cool: ;) I still got one , found it clearing out the old layout. :thumb:
  13. northern_blues

    northern_blues New Member

    Duckman, looking forward to the info about making molds. I've seen a couple of websites that use silicone for molds.

    I hear you about having sound benchwork as a prerequisite. I'm sure that's not a problem as my benchwork is using 3X3 L-girders, 3X1 joists spaced 14" o.c and 2X2 legs on levelling bolts. All screwed and glued and gotta be strong enough.

    Again, my only concern was if I lay 2" of foam as a bed for everything, I just wanted to make sure heavy hydrocal structures didn't dent the foam. For example, a 3-stall roundhouse I have my eye on is listed as 3 pounds!

    I think I'm going to lay 1/4" plywood on the joists first and then go with the foam glued to that. Seems okay.

  14. Bikerdad

    Bikerdad Member


    Do a little work finding your foam. It comes in various grades, including some that you can stand on in street shoes (i.e. with heels) and not dent. I know, because I've tested it. Up there in the Great White North, you should be able to find the tough stuff without too much trouble. Just check with a commercial insulation supplier.

  15. northern_blues

    northern_blues New Member


    Sure, I'll do that. It would be useful to know as I've only worked with pink fibreglass insulation in my home and hadn't even seen the rigid stuff until I went looking at Home Depot.

    Not much of a selection there, though.


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