Weathered Concrete

As with all building materials concrete has a vast range of colours depending on what it's used for. Road surfaces tend to be cream in colour, which 1960's tower blocks are grey. Best advice would be to get loads of photographs of your desired concrete structure to get the right shade.
Once you've got that, next thing is surface texture on the structure. Concrete is never perfectly smooth. On structures I've scratch built, I give the surface a very thin skim of decorators filler, which is rubbed down after dry to get the required finish. Again research is important here. Old concrete will be more 'weathered' then new. It will also have chipping along edges and may even have signs of crack repairs or have rienforcing rods exposed. Also consider scale here. What looks good in 'OO' would be way too course in 'N'.
Once repeared, paint the structure in the desired colour. Once dry, give the structure a wash of a darker colour to pull out the surface imperfections and aging - black, brown or grey will give different results. Then dry brush on the desired colour followed by a light layer of a lighter colour to highlight areas.
Final stage is weathering.
As with all buildings, I tend not to use the colours straight out of the tins unless it's for a base colour, try to vary the colours slightly by mixing in a touch of brown, grey or what ever colour before applying it to the model....

Hope that helps, Al.

What is with certain recent postings?! Are some people so devoid of social skills that they need an online guide written containing such guidelines as, don't be rude, don't demand explanations for personal choices, don't insult the intelligence of established posters with your first post on the forum etc. etc.

QUOTE (Al)On structures I've scratch built, I give the surface a very thin skim of decorators filler, which is rubbed down after dry to get the required finish.
That sounds a very good way of creating the impression of a concrete structure that is actually built from something else.

What would you use for say concrete arch bridges that support the railway over a valley etc.? Would unreinforced decorators filler be strong enough if used in a wooden mould with perhaps wires in it to strengthen it?

QUOTE (goedel @ 2 Jan 2008, 01:38) <{POST_SNAPBACK}>What is with certain recent postings?! Are some people so devoid of social skills that they need an online guide written containing such guidelines as, don't be rude, don't demand explanations for personal choices, don't insult the intelligence of established posters with your first post on the forum etc. etc.

That sounds a very good way of creating the impression of a concrete structure that is actually built from something else.

What would you use for say concrete arch bridges that support the railway over a valley etc.? Would unreinforced decorators filler be strong enough if used in a wooden mould with perhaps wires in it to strengthen it?

***
Well said.....

Re "basic" concrete: Use a plain old aerosol pale gray undercoat from whever does your local automotive spray cans... then weather with dilute paint, powdered weathering materials & whatever - it will take water base or oils no problem.

re: "Real" Concrete: As already stated, there is no "Generic" colour. Cement itself is always a plain pale-ish Gray but the colour of the (even clean) concrete will quickly take on a tint depending on the sand and gravel used in the making of the concrete... it can be yellowish, pinkish, Gray/blueish... depends on the location and source of the materials. This "tint" is amphasised as wear and time progress.

Add to that the situation it is laid in and then its clear that concrete colour" is indeed as A1 alluded to, totally dependent on age, wear and location.

Look at local pictures and make your own decision - experiment on a test piece - as a hint lighter is usually better - its easier to darken than lighten later.

Model what you really DO see, not what you think you see! Decide whether your local concrete is "Warm" in tint (add yellow/orange/red/brown to the paint mix) or cold (add white/blkack/green/blue). Do it very gradually and paint samples / let dry before adding more tint .... Make notes so U can repeat it.

***Re using non-reinforced plasters: Yes it can work but it might be a harder than necessary way to do it. The basic shape is more easy to create with a solid material as the "basis" for the concrete beam.

I tend to add a layer of DAS modelling clay to a former or shape made of thin ply, balsa or card: It is stuck to the card with plain old wood glue brushed on.

To make rolling the DAS easier for big projects I use a Pasta maker - it has adjustable rollers and you can create a nice even sheet of DAS in a few minutes with it. I cover it by placing the former over the sheet then simply cutting out a little generously with anything sharp. I cover both sides, tidy up and let dry for about 24 hours, Sand if needed (plain old sandpaper glued to a wood offcut for bigger flat areas) and carve any stonework, blocks or lines with a cheap vibrating engraver (about a tenner). Dead easy and very good for "look".

It takes paint really well, doesn't crack and is dead easy to patch and fill with more of the same. Less messy than plaster too!

BTW a stainless steel pasta maker should be less than 25~30 Euro, and as DAS is water based a quick wipe and pasta can still be made

Richard

Thanks Al, I will give your suggestion a try.

Cheers
Dave.