Can Mdf board be plastered?

[EarlyMornings]

Greetings,

I have recently built a dolls house in 1/12 scale out of mdf board (6mm)

I have a few ideas for decorating the outside walls, and I would like to ask please if one can plaster mdf board for a rendered/limestone look
if so, what sort of plaster would be the most appropriate to use? How thick can it be placed on, would it crack with temperature variation? fall off after a while?
I have also been considering using pebbles for a 'stone cottage look' but would like to be able to fill the gaps between.

wouldn't mind doing the same for the inside.

Can this be done successfully?

Many thanks

EarlyMornings

[pawnhead]

I know that MDF stop ends (http://www.lifetime.net.au/MDF.htm) are used extensively in partition work. The edges are taped and set onto the adjoining plasterboard, and the end of the wall is an MDF strip that's durable and ready to paint. It saves time not having to install external corner angles. That's plastering onto the more fibrous edge grain of the MDF though.

I'm not so sure how it well it would stick to the smooth surface. I'd be inclined to rough it up with some coarse sandpaper first.
If you post this in the Plastering (http://www.woodworkforums.ubeaut.com.au/forumdisplay.php?f=79) section, we have a resident expert (http://www.how2plaster.com/) who is always ready to answer any questions about plastering. I'd be interested in Rod's opinion myself.

edit: I did a partitioning contract a while back and my plasterers used mdf stop ends. With one booth we lined it with 16mm mdf because the booth owner was going to hang a lot of heavy clocks on the walls (for sale) in various locations. In this case the joints were just butted and they were hardly noticed after the painters had treated the wall to a black marbling effect.
But I'm wondering if it would be possible to tape set the joints flush, by planing a bevel on the sheets prior to installing. :?

[SAISAY]

Wonder how much booze it would take to get MDF plastered :D:U
LW

[echnidna]

You might be able to achieve a stone finish effect by gluing sheets of very coarse Garnet paper to the mdf then lightly plastering over the top.

You would need to blunt the garnet paper by rubbing on some steel plate or flat concrete before you did it.

Probably a worthwhile experiment on some scrap to see if you can get an acceptable result.

[pawnhead]

Wonder how much booze it would take to get MDF plastered :D:U
LWWell if it's High Moisture Resistant MDF then it would take lot, but if it's regular MDF then it would probably be having a 'swell' time as a two pot screamer. :p


http://i7.photobucket.com/albums/y266/holgerdanske/hohohosmall.gif

[Pusser]

Intersting info Pawnhead, my first thought was that the dampness in plaster would cause problems with the MDF - live and learn.

My thought is that on a model you could achieve the same effect with paint. When making scale models as a boy the impact of the original finish was an issue. You need to scale the look, ie canvas on a plane model could not be simulated using the real product as the graininess was not to scale. I think the same would apply with a limestone finish. The same would apply to pebbles - you would need to use very small ones to get a reasonable scale. You can get high quality styrene panel cladding finishes to scale in model shops which can be cut and look realistic.

[pawnhead]

You might be able to achieve a stone finish effect by gluing sheets of very coarse Garnet paper to the mdf then lightly plastering over the top.That's a good idea. :2tsup:
It would look just like a cement rendered house.

[rod@plasterbrok]

Good Question!

Yes and No is the answer.

In variaious applications plaster and MDF can work together as stated by Pawnhead in the partition industry. Athough I have seen these joints form a fine hairline crack over time.

MDF can be patched with top coat quite well with no problems. That is small indentations etc.

Joins in mdf cannot be taped and finished with plaster they will eventually crack and or the tape will lift. The thicker coat of plaster will expand and contract with heat at a different rate as mdf causing the joint to eventually fail.

When putting cornice around an mdf bulkhead you need to screw the cornice up because the cornice adhesive will not bond well to the MDF.

I would look for an alterative for the dolls house or cover the mdf with fine wire mesh then plaster over the mesh.

Cheers Rod

[echnidna]

Mix the dry plaster with some pva paint instead of water and apply it.
You won't have a long working time but it grips very well.

[EarlyMornings]

Greetings All,

Thank you kindly for all your replies. Very much appreciated, John, Bob, Rod.
I like the Garnet paper idea, sounds like the look I want...old world, rather than modern.
Thank you for the cornice information also. I was going to add these today.

Thanks for the chuckle LittleWolff :-)

Thanks again, have a great week everyone
EarlyMornings

[echnidna]

post pics so we can see how it goes

[Wood Worm]

One technique I use in making models is to mix PVA with water to thin it down and add a little liquid detergent as a wetting agent. Paint an area with this mix and then coat the surface with a tissue. Smooth the tissue out with the PVA mix on a brush. Slowly coat the whole surface with a layer of tissue. Finish off with a dusting of white or coloured grout. Experiment on a spare piece to produce the desired degree of texture. Paint the surface with water based paints when fully dry.

This method produces a very strong surface bonded to the timber. I mainly use it for landscaping in 1/87 or 1/43 scale. A flat surface painted grey resembles concrete and black resembles bitumen.
Kerry

[Pusser]

I second wood worm. Real plaster will never really look the goods. and will be heavy and tend to chip off given the handling a dolls ouse is likely to get.