Spray Chalk Outline
Scroll down for spray product information
The stencil in this photo is designed for spray-chalking
pavement. It is long enough to put one's feet on its ends to hold it down while
spraying, if you don't mind overspray on your shoes..

If making many symbols in one day, eventually the residue on the
stencil will become sloppy and contaminate the underside creating a mess on the
pavement. Something like paper towels will be necessary to dry the stencil from
time to time. Wiping it
off will solve the problem and it can be put right back into use.
Another issue is how to carry the wet stencil without
blotting it dry after every spray. Stapling furring strips to each end would
create a handle on one end while weighing down the other to reduce its tendency
to flop around depositing wet chalk on the person carrying it.
Avoid vertical surfaces
Rain usually cannot remove chalk from them
I could not find spray chalk at Wal-Mart or Michaels or Sams.
And the building supply companies like Lowes and Home Depot had only pavement
marking sprays that were too permanent. However, I did find something at Hobby
Lobby.
Air Chalk.
Recommended. I tested a brand of spray chalk called "Air
Chalk" distributed by Goodmark. It's the correct light, bright blue for this
symbol. It sprayed well and could be removed with a hose. A 3
ounce can is small and cost $1.99 (in 2008) at Hobby Lobby,
but it is pocketsize, which is handy. The top image at right is how it looks on
concrete.
As of late 2010 this product could be purchased for $3.50 online at this link:
http://www.abrivosports.com/spray_chalk.htm
For other sources, the importer says
Wal-Mart carries it, though I could not find it there. At Hobby Lobby the
manager finally found it in the seasonal section. Next time I'd just get it
online.
At the Abrivosports link above, they also have a product called "Chalk-It" that
is less expensive per ounce. In the photos it doesn't appear to show up as well
as the Air Chalk, but I haven't tried it to really know about that or whether it
washes off. Let me know if you do.
Inverted Marking Chalk .
Not recommended. One company for this that I
found on the web is Cornerstone.
The cans are held upside down, as are most pavement marking products other than Air
Chalk. In 2008 they sold
individual 15 ounce cans for $4.25 each (shipping a single can is $4.25).
The instructions say not to apply it if it is going to rain within four hours.
It had rained half an hour before I applied it to wet pavement. Within an hour
it rained again. It was unaffected. Four hours after applying it, when things
had dried out, I sprayed it hard and long with a hose. The image became slightly fainter
but did not wash away. This product is too durable and turns your message into
graffiti that is more likely to turn people against you than to persuade them of
your message.
Also, this product has such a strong blast that overspray is a problem. Stencils
would have to be masked at least a foot in each direction, making it 3 ft. by 3
ft., a large cumbersome stencil with which to deal.
Air Chalk is a better solution.
Rust-Oleum
Spray Chalk. Not recommended. Kuzsports,
in 2008, sold this in 17 ounce cans for $6.00 ($9.27 shipping and handling for a single
can that can take 5 days to arrive) or a case of 12 cans for $62. One can sprays
a line 500 feet long (which I'm estimating will spray 150 templates). It has
overspray problems, but its main problem is that it is paint. When trying to
remove it the hardest spray from a hose had no effect. The can says it is
water-soluble, but it isn't. This is the wrong product to use for this purpose.
Upside-down Marking Chalk. Untested. This company, found on the
web, sells spray chalk in cans that cover 500 ft of linear stripe per can. The
company is Time Striping,
Inc. It's $40.00 per case (and by the case only). They say it lasts up to 30
days. "Up to" is good news, but after my experience with the last two
similar products, I'm not inclined to get a case of it to test
it.
"Super Spray Chalk" by Rapid Mounting & Finishing Co.
I was contacted by someone who used this and said it washed away about as
quickly as standard children's chalk. If you want to see what she did with it,
she wrote about it on her blog at this link:
http://vogie13.blogspot.com/2010/08/large-footprint-stencil.html
Home Made.
This is the basic recipe people have used.
4 Tablespoons cornstarch
1 Cup warm water
4-6 drops food coloring
1 spray bottle
1. Mix ingredients in a bowl.
2. Pour in a spray bottle. Shake repeatedly as it will clog if you let it
settle.
Someone who has written about her experience making it work
is at this link:
http://vogie13.blogspot.com/2010/08/spray-chalk-recipes.html
If you try it too, let me know what you learn. I'll share it
here or link to you.
When two colors overlap, the double coat of the overlap
can be difficult for rain to remove
One citizen, tired of looking at someone's message on a
sidewalk, tried washing the spray chalk off and could only partially remove it.
That became an
issue in the news. That would be bad public relations for this cause. Please
use the least durable products possible.
Spraying chalk on lawns might eliminate the problem of
enduring longer than is desired. It will be gone when the lawn is mowed. (Won't
it? It appears to have disappeared from my lawn with one mowing, but dew and
rain preceded the mowing. I need to test it in dryer weather).
Rainbow Racing Systems, Spokane Washington, (800) 962-1011 or
(509) 326-5470, says that their spray chalk is "Not recommended on concrete,
brick or porous masonry surfaces" because it can stain permanently. It is better
on asphalt and grass. Other brands have the same problem, but don't
warn us.
Below is a test of repeated use of the stencil with Air Chalk
(on my driveway)

Something that might be worth investigating is
Fisher-Price's Chalk Art Blaster, a child's toy for squirting chalk on pavement.
Let me know if you do and how it goes.
Please don't use spray paint or
anything permanent on a sidewalk or other public place. If it is permanent, it
is graffiti and is more likely to alienate than to persuade (and might be
illegal). Christo left his mammoth exhibit of 7,500 Gates in Central Park in
Manhattan for less than three weeks because it is special and poignant if it is
rare and of short duration. Chalk outlines still on the ground after 3 months
may work against us. It is important not to be obnoxious to our own
constituency. |