I'm looking for ideas on how to represent a dried up river bed. I would like to show dried cracked mud.
I thought I would try a thin plaster mix and heat dry it quickly, causing it to crack hopefully????? what do you think? Sugestions welcome.

That sounds like a good idea. I would use a small test sample just to test it.

Another idea is to scibe in lines with a dental tool.

Maybe a too thick layer of paint, that usallu cracks when it dries. And then fixate it with a water/woodglue mixture.
I don't know but it might work.

How about letting the thin plaster dry completely and then give a few hits with a hammer and then just gluing the pieces onto the base?
Kyle

1) real dried mud cracks are only a few millimeters wide and individual cracked pieces are only a few centimeters large, so at 1/35 this would be barely visible. Since you want to give that impression anyway, your cracks should be V E R Y small indeed.
2) the best way to represent this, would be to use a paint that has a cracked surface. Try any website on the subject of furniture painting effects to find several ways to do this.
The first would be to apply a special liquid that is made exactly for this "cracquelé" effect, and then paint a layer of paint over it. In only a few hours, it will show the perfect cracked result.
A cheaper way would be to apply a layer of very slow drying paint or varnish (glossy, oil based) and after about an hour to several hours '(TEST WITH DIFFERENT TIMINGS ON SEPARATE SURFACE FOR BEST EFFECT BEFORE APPLYING TO DIORAMA !) add a water-based matte paint in the mud colour of your choice.
I never tried this for a diorama, but this is a classic technique for furniture decorating. Please look for websites that explain this process for details.
It will take some testing to get this right,, but it works.

You could use fat lime putty instead of paris plaster. If you will not add any aggregate, fat lime cracks a lot without fast drying. The more water you add to the mixture the more it cracks. Actually you can add simply a thin layer of lime wash (not very thin) to an already set surface and have the same result. There are two problems, it is not very adhesive so experiment a bit with different substrates and i am afraid it comes only in large packs of several kilos (but still chip).

This would all depend on the consistency of the mud and how wet it was. I have seen bogland that is wet 75% of the year, when its dry you could put your foot in the cracks. Also have seen river beds that have dried up, and left huge deposits of silt. When this dries, the cracks can be huge.
To be sure, reference would be the best. Sometimes even if the cracks are barely visible in 1/35, they can be exaggerated for effect.

I have achieved this effect with vinyl spackle(in the tub).
Take some in a seperate container and stir in water till the consistency is like cake batter.Spread thickly and quickly.Put in warm sunshine for a while and,WAH-LAAA,summer creek bed.
cheers!

Go to home depot and pick up a small jar of taping mud for sheetrocking. If spread on thick, it will shrink when it dries, naturally causing cracks.

Roger-

Plaster will crack if its has too much water mixed in. As it dries it will tend to crack along the weakest links. However you wouldn't be able to control the pattern of the cracks.

If your'e upto playing with dirt here's an easy way, at least it was easy for me. Dirt or soil with a high clay content cracks very well when dried. To find out if the soil has a high clay content as opposed to sand is to wet a lump of it, mash it around in your hand and try squeezing a ribbon between your thumb and forefinger. The longer the ribbon formed without breaking the higher the clay content.

Next sieve the soil to get out as much clay as possible as clay will be found as the smallest particle of the soil.
Then mix the sieved portion with a very diluted PVA:water mix (30% PVA: 70% water) until you get a slurry with the consistency of melting ice cream.

Apply over dio base in a thin layer. The thinner the layer (2-3 mm) the finer the cracks. Avoid going over 5 mm. thickness as the soil will find it hard to crack. Dry either in direct sunlight or in airy shade area. Cracks will appear automatically and the soil will remain stuck to the dio base. You can just barely see the fine cracks this poorly take picture towards the center of the dio:


I'd have to go with Plasticbattle on the size of the cracks. The size of the cracks is due to the amount and type of clay deposited on the river bed. As a very rough approximation more clay and if its really dry = bigger cracks.

Thankyou all for your tips and sugestions, I will experiment and see which method I like best.
watch this space.......

First, make a pot of coffee.
Second, enjoy a cup (or two) of said coffee.
Three, don't throw the coffee left in the filter away, but mix it with some PVA glue and water.
Four, spread this in your riverbed and let it dry.
Five, have another coffee...
Admire your dried, cracked mud effect.
This will create very fine, small cracks, which depending on the size of your river, should be just right. The coffee gives it a nice color, but you can paint it to your requirements.

Cheers
Henk

I like the idea of a pot of coffee. At least drinking a few cups might give me the courage to try what you want to do w/ the dry river bed. Someone mentioned experimenting on something throw-away first. Very good idea.

By mistake I found a method to make mud crack. I was mixing real dirt w/ a little white flour, white glue and water in a plastic lid. I spread it on the base and let it dry. There were tiny little 1:35th sized cracks all over the base, when it was completely dry.

And of course, real dirt is a lot less expensive than buying something at the hardware store. And it sets up hard because of the white glue and flour. But you can still cut it or chisel it, etc. Good luck and hope you can show "under construction" photos during the build. I have a dio idea myself. . . . but still need more coffee, to provide enough courage to start in the first place
Regards, :-)

Thanks yet again guys, I have been experimenting with thin Plaster of Paris, I found that it didn't crack by itself, so I simply put som pressure on it and it broke up. Nice effect but I will continue with some of the other methods. Thanx

try rolling a sheet of thin clay out and drying it, should give you that dry cracked design

reb

Well guys, I've been experimenting with various methods that have been offered up by yourselves and I think I've found the method I like best, that will suit my needs.
I used garden soil, mixed with PVA and water. The mix was the consistancy of sloppy ice cream. This mix was then set aside to dry. Once the mix had been left for about an hour, a skin had formed across the surface. This was then left for a further hour or so.
I then used a hair dryer to finish the drying process. As the heat of the hair dryer did its magic, tiny cracks started to appear......perfect!!
Once again I would like to thank all of you who gave hints and sugestions. In my opinion, this is what the forum is all about.
Cheers!

Nice work Lt-Shultz. Nature is still the best substitute for representing nature. As I mentioned in my earlier post if you need finer cracks just apply the clay thinnly.

Just a small comment though. If your'e going to leave more stones on the river bed it would be better to have more rounded ones as opposed to those with sharp edges due to the action of moving water. If your'e really into accuracy, then some of these stones would be covered in a film of mud/dirt similar to your river bed especially if they were totally submerged before the river dried out. A very minor suggestion though.

Alright Beachbum:

Just a quick comment to aplaud your suggestion about stones in a dry creek/river bed. Right on the money. . . and I never would have thought about how "nature" would work in that "setting". I won't forget what you said.

Regards,

No worries MiamiJHawk. Your'e more than welcome.
If it helps take photos of nature scenes you wish to represent. Observation is all you need.