Washago coaling plant--step 6

As you can see above, pouring hydrocal into narrow openings can be a messy business. No matter! Just make sure that you work on a level surface, and gently tap the base on the table top to bring air bubbles to the surface. The right consistency of hydrocal is achieved with a 2:1 mixture (hydrocal:water). Make sure the poured plaster overtops the formwork.

Before the formwork was removed, I used a cheap hardware store scraper (which consisted of a single-edged razor blade in a plastic handle) to gently scrape off excess hydrocal almost to the top of the formwork. This was done after the plaster had set, but while it was still damp. Then I turned the assembly upside down, formwork and all, and rubbed it on a piece of coarse sandpaper until the top of the plaster was level with the top of the formwork.


When you are satisfied with the top surfaces, gently peel off your formwork in reverse order of how it was attached. For the plug in the wall section, I used a spade bit in an electric drill at slow speed to gouge most of it out; the rest came easily.


I mentioned that I positioned my opening in the wall in the wrong place. A few minutes with a X-Acto knife were sufficient to trim out a portion of the wall and replace it in the correct orientation. Hydrocal is an amazing medium--the cracks were filled with soupy plaster applied with a cheap paintbrush. This patching mix set instantly upon making contact with the finished surfaces. Then it was a simple matter of using the scraper to smooth over the joints.



Here is the prototype. The portion of the structure we have just finished can be seen at the bottom. The rails to the receiving hopper were laid flat on the top of this concrete section. About half of this first section is buried underground on the outside, but the grating, hopper and machinery were on the inside.

That will be it for a short while; looking forward to hearing from other modelers undertaking this project! (click on "comments" under any relevant posting).