So I have a small diorama from MiniArt and it is a vac-form kit. I would like to fill the base with something to make it solid. Anyone have any suggestions.

TIA

Well,you could use liquid plaster or resin to fill the hollow base.Depends if it has holes or something like that.I would go for resin,because it bonds for sure according to my experiences and it´s pretty durable to pressure and is unaffected by humidity.

Ummmm, resin can generate heat during the curing/hardening process and I can not guarantee that the vac-formed base would stay in the same shape.

Check building supplies for various types of plaster. Here in Sweden we have a sort of hybrid between plaster and concrete which hardens to something which is harder than plaster but softer than concrete. It bonds fairly good to plastic, even the "greasier" plastics like polythene.
Check for putties/plasters that are to be mixed with water.

/ Robin

Tile Grout works well on those floppy bases. I was very pleased with the results achieved when using it on a MiniArt 'Russian Street' diorama. The rigidity and weight of the grout added a nice stable feel to the base. Just make sure to allow plenty of curing time. HTH.

—mike

If you use plaster or hydrocal to fill the interior and pop it out when it's set, you'll have a plaster casting of the base.

@RobinNilsson: It may be that there is a little heat generated when resin hardens,but i did it myself and nothing happened.Example:


Styrol frame,Styrol Model,one base layer poured (200 gramm resin),waited overnight to harden,poured second layer of the same amount,let model swim in it.No warping or deformation.
I guess the more resin you use at the same time,the more heat can be generated.In moderate amounts,it´s quite neglectable i think.

Thin layers and moderate amounts is the important message

as an alternative to any of the above, sprue cut to fit should work and glued on smaller bases. did that with my country road/wall. stiffened it up nicely

Thanks for all the input kinda leaning towards the grout but I like the sprue idea A LOT because it is FREE. And I have a lot left over from my current build.

iffn you go that way, make sure any large/angled sprue gates are removed

I used sprue chunks and Evergreen strip to reinforce my base. Worked a treat. The bond between the pieces of styrene is the best its going to be (occasionally the epoxy , hydrocal or grout doesn't actually stick to the base. It mechanically locks in, but a flex of the base and the filling is on the floor!

Styrene stiffeners are as bonded to the base as the other parts of the base are. I like that.

Stiffening with styrene also doesn't add a lot of weight to the base. This may, or may not, be what you're looking for. Sometimes you want/need to increase the mass to prevent other things moving or dampen the effects of vibration or movement of the entire base.

Just a couple of thoughts on the subject.

Paul

Use bits and pieces of sprue to make a structure that the grout can key in to?
The sprues give the bond and strength and the grout provides the weight/mass.
/ Robin

stiffen with sprue then fill with Durham's Rockhard Putty.

http://www.waterputty.com/

A technique I've used with a few of the old bases included in Aurora and KB model kits many years ago was to use spray foam insulation. It keeps the base nice and lightweight, but it's a lot messier. You just need to control the amount of foam used, and then when it's dry in about 15 minutes, hack off the bottom of the foam with a hacksaw blade. It keeps the base rigid while keeping the weight down, and is quick and cheap.
VR, Russ