# Applying mortar to HO scale buildings



## babu2 (Jun 8, 2015)

Can someone offer some advice an applying mortar to brick buildings? I have been using some plaster and I get an aged look and many times it does not apply uniformly. I would like to apply mortar only with the bricks remaining clear and new looking. I would appreciate any help in the area of terminology for this process as I would like to look up some videos on youtube to aid my educational.


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## tr1 (Mar 9, 2013)

*mortar application suggestions*

Sounds like a little experimentation until your satisfied with the final results, on the brick masonry
work. I experienced this same problem about getting unsatisfactory results. Flat paint with a quick wipe off. I think, it would render smudges on the plastic brick work. That you had mentioned earlier using a form of plaster. A water based.plaster mixture though may work, 
after drying times are determined for the water based wipe off the
extra plaster. 
The plaster I had very good results with.The kind we are both looking for. "Hydrolcal" casting plaster.
That plaster has the proper results Water base,... let dry wipe off, maybe polish off. That will give you the very fine mortar lines your looking for. Good luck,tr1


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## Patrick1544 (Apr 27, 2013)

I use thinned white or light gray acrylic paint for filling mortar lines on plastic models. I thin it out about 2 parts paint to 1 part isopropyl alchohol 90% strength. After applying to a small section at a time, wipe it lightly off the brick faces only. Hope this helps you.


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## tr1 (Mar 9, 2013)

*motar line suggestions*

Water based products should work after a little experimentation.


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## wvgca (Jan 21, 2013)

on smooth brick i have used ordinary drywall compound, thinned somewhat, tinted sightly for 'gray' colour and brushed on... when dry a firm damp sponge removes excess off brick faces ..hydrocal is not water soluble when dry / cured..


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## CTValleyRR (Jul 26, 2014)

First of all, if you're trying for uniformity, you're aiming for the "better homes and gardens" touched up photo look, not realism (and if you don't give a hoot about realism, why worry about mortar lines).

I use off-white acrylic paint (formerly Polly Scale's Dirty White, now Vallejos Ivory or Stone Gray), thinned 10:1. Make sure your wall is horizontal (otherwise all the paint will run to the low point) and apply to the wall with a soft brush. Use the brush or a paper towel to remove any blobs. Allow to dry. If it isn't dark enough for your taste, repeat until it is. Once the paint is dry to the touch, rotate the model and do another wall.


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## SBRacing (Mar 11, 2015)

Woodland Scenic makes a foam putty and it comes in white. I havent tried it but you could make it a little more "runny" (bad choice of words). I you haven't use it before or heard of it you have to mix it with water to get a consintancy to ure desire. Once you get it to your mix I would assume you could put it on the buiding and use a putty knife to smear it over the cracks. I may try this and post pics of the outcome.


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## sstlaure (Oct 12, 2010)

I simply use grey weathering powders for mortar. wipe it on with your fingers, then wipe off the surface of the bricks, then apply a thin coat of flat finish lacquer over the top.

Here's a pic of a building I did this way. If you don't like how it's turning out you can simply wipe down with a wet cloth and start over.


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## traction fan (Oct 5, 2014)

*Mortar lines*

babu2;

On plastic structure kits, I use thinned acrylic paint, brushed on. After the paint dries, I lightly
sand the brick faces with 600 grit sandpaper. This not only removes the excess mortar, but also the plastic shine from the brick faces.

Traction Fan


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## Southern (Nov 17, 2008)

Scott that mortar work looks great!


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## CTValleyRR (Jul 26, 2014)

SBRacing said:


> Woodland Scenic makes a foam putty and it comes in white. I havent tried it but you could make it a little more "runny" (bad choice of words). I you haven't use it before or heard of it you have to mix it with water to get a consintancy to ure desire. Once you get it to your mix I would assume you could put it on the buiding and use a putty knife to smear it over the cracks. I may try this and post pics of the outcome.


I have used the WS foam putty, and it has a very thick consistency out of the jar. I'm not sure you CAN thin it, but even if you could, it would take a heck of a lot of effort to get it thin enough and smooth enough to use for this purpose.


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## SBRacing (Mar 11, 2015)

I thought it did say to thin it out with water. Oh well I may be fabricating that. 

And I reckon it dont have to be perfectly smooth if its an older bilding.


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## CTValleyRR (Jul 26, 2014)

SBRacing said:


> I thought it did say to thin it out with water. Oh well I may be fabricating that.
> 
> And I reckon it dont have to be perfectly smooth if its an older bilding.


Actually, I'm wrong about the thinning part. The instructions say to dilute with water if it's too thick.

That said, though, those little lines on an HO model are about 0.5mm thick. Even a small chunk in your paste would be an enormous boulder stuck to the wall.


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## MikeB (Feb 11, 2016)

Found this thread while searching brick mortar. Saw a video on model railroad academy where they thinned paint 50/50 with rubbing alcohol. They just touched the bricks, and the paint wicked through the mortar lines. Results were very close to the pictures that sstlaure posted.


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## CTValleyRR (Jul 26, 2014)

MikeB said:


> Found this thread while searching brick mortar. Saw a video on model railroad academy where they thinned paint 50/50 with rubbing alcohol. They just touched the bricks, and the paint wicked through the mortar lines. Results were very close to the pictures that sstlaure posted.


Well, yes, if you read the thread, this technique is essentially what most of us are recommending. As I said previously, though, it's more realistic to have some lighter patches on the bricks themselves as well, not just in the portar lines.


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## MikeB (Feb 11, 2016)

For some reason, maybe the type of paint I used, I could not get the thinned paint to wick along the mortar lines. Wound up using a pastel drawing stick. I then tried to highlight some bricks. This is the first time trying this so, I'd like some comments please.

Note: most of this wall will be hidden under a concrete deck. I changed a window on the top floor to a door, and will place the deck at that level. The deck will join to a pizza parlor across the road.


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## traction fan (Oct 5, 2014)

*Looking good!*



MikeB said:


> For some reason, maybe the type of paint I used, I could not get the thinned paint to wick along the mortar lines. Wound up using a pastel drawing stick. I then tried to highlight some bricks. This is the first time trying this so, I'd like some comments please.
> 
> Note: most of this wall will be hidden under a concrete deck. I changed a window on the top floor to a door, and will place the deck at that level. The deck will join to a pizza parlor across the road.


MikeB;

Your brick wall looks quite good! That's a great first attempt. One bit of advice, Less is more, or rather less looks better. Brick walls vary a lot in appearance depending on the age of the structure, how much dirt is in the air and weather. One thing that happens easily when we try to do brick is that mortar lines tend to overwhelm the bricks. There's a few tricks that minimize the "mostly white wall with red checks on it " effect. 

1) Use a dull, flat gray mortar. Real mortar is rarely white.There are exceptions. A brick home in a wealthy area or some urban renewal project where the walls have been recently sandblasted. There's also a lot of fake brick in today's world. Your local shopping mall probably has some, and it will look pristine. Common mortar's natural color tends more to concrete gray. Mortar, and bricks, weather pretty quickly, so even if it starts out white, the white color soon fades.

2) Use less mortar. Real mortar is set back about 1/2" behind the brick faces. Models tend to have the mortar even with the brick faces, which helps with that overwhelm thing.

3) Use dead flat mortar. Real mortar is not shiny at all. It's dull, rough surface reflects very little of the sunlight that hits it.

4) weather it right away. Since real mortar starts out gray, and collects dirt quickly, brick walls look more realistic when they have some dirt on them. (See the photos below for different brick & mortar color treatments.)

My favorite mortar material is chalk. It is available in many colors including grays and white, tan and black for simulating old dirty walls in a run down industrial area. I bought a set of a dozen sticks of pastel chalks years ago at Walmart for $3. I'm still using them. If you decide to try chalks, be sure to get "pastel CHALKS", not just "pastels." The latter are more like crayons, than chalks. Chalk is also useful for all sorts of weathering effects. The boxcars in the tug & car float photo are weathered with chalk, not paint. It is possible to "Paint" with chalk however. I dip a small artist's paintbrush in plain water, drag the wet brush along the length of a chalk stick, and then paint the water/chalk mixture onto the model. Very little color shows at first, but when the water evaporates, the color shows.

good luck, have fun!

Traction Fan :smilie_daumenpos:


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## flyboy2610 (Jan 20, 2010)

MikeB said:


> For some reason, maybe the type of paint I used, I could not get the thinned paint to wick along the mortar lines. Wound up using a pastel drawing stick. I then tried to highlight some bricks. This is the first time trying this so, I'd like some comments please.
> 
> Note: most of this wall will be hidden under a concrete deck. I changed a window on the top floor to a door, and will place the deck at that level. The deck will join to a pizza parlor across the road.


That doesn't look to bad at all!
When I built the Walther's Champion Packing House kit, I used VERY thin wash of paint. That flowed nicely into the mortar lines. When the wash was dry I used dry cotton balls and paper towels to scrub the wash off of the brick faces. It turned out pretty well. I wasn't able to scrub all the paint off of the bricks, but I think what was left gave the brick a nice dusty weathered look.
Here's a photo showing all three steps:


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## MikeB (Feb 11, 2016)

Thanks for all the help and advice. Hopefully I'll get better with more practice.


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## MichaelE (Mar 7, 2018)

Patrick1544 said:


> I use thinned white or light gray acrylic paint for filling mortar lines on plastic models. I thin it out about 2 parts paint to 1 part isopropyl alchohol 90% strength. After applying to a small section at a time, wipe it lightly off the brick faces only. Hope this helps you.


This.

But I use water based acrylic.


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