Street wall installation for creating interactive murals that can be built up and scrambled over time.

Components of the Graffiti Jumble

Grid: The grid of squares are made up of equally sized pieces of wood with magnets attached on one side and a flat surface on the other. The surface provides a blank, movable palette for art to build up over time. Once the surface is painted, pasted or stickered with something, the squares can be rearranged to produce a new canvas. The next person to add to the surface can change his or her palette, while providing a new background for the next artist to tag.

Frame: The frame sets the boundaries of the grid and prevents the magnetic squares from sliding down the wall's surface. (Even strong magnets slide easily.) The frame will be bolted or screwed to the wall.

Magnetic Surface: A magnetic paint undercoat provides the surface to which the magnetic squares will stick. Since large iron structures are rare in most urban areas, any surface can be made magnetic with the use of magnetic paint. Once you choose your location, you will have to paint the surface 3-4 times before attaching your frame and squares on top of it.

Step 1: Gathering Materials

The first and most interesting part will be finding the material for the squares of your grid. Many sheet materials can be used, but I preffered using street wood (generally Plywood or MDF) because it is rather abundant, tends to have more intrinsic character, and can be a good way to recycle stuff that already exists on the street.

Just be discriminating when you pick up street wood! It can have embedded hardware which can be extremely dangerous and cause injury when cutting on machines.

Materials List

Plywood
Amount: Approximately 9 Square Feet
Cost: Free, off the street.

MDF
Amount: Four strips between 2 and 4 feet long, 3/4" inch to 1 1/2 " inch wide.
Cost: Free, off the street.

Magnets

Disk Magnets: 3/8" inch x 1/8" inch NdFeB Disc Magnet, Ni-Cu-Ni plated Reccomended
Amount: Approximately 100
The number of magnets you need depends on the weight of the material you are using and the strength of your magnet. I used four 3/8" x 1/8" magnets on my 7" x 7"squares of 1/2" inch thick Plywood. You may need more or larger magnets for thicker/heavier materials.
Cost: $20
http://www.kjmagnetics.com/proddetail.asp?prod=ZD1
http://stores.ebay.com/FORCEFIELD-MAGNETS

Magnetic Sheets
Amount: Approximately 9 square feet
The amount you need depends on the overall surface area of your squares. Magnetic sheeting does not have as strong of a force as NdFeB magnetic disks and may not work as well for thicker/heavier materials. I'm suggesting this as an alternative method for those who may not have access to all of the tools necessary for attaching the magnetic disks and have not modeled a version using this material myself.
Cost: $5 per 24" inch x 12" inch sheet
http://www.dickblick.com/zz289/21/

Magnetic Paint
Amount: 1 Quart
Cost: $15
http://lyt.com/

ALTERNATIVE:
Magnetic Spray Paint
Amount: 1-2 Cans
Cost: $10 each
http://www.dickblick.com/zz014/10/

Additional Materials to acquire at your Local Hardware Store
Primer
Wood Glue
Epoxy
Paintbrush or Roller
Nails/Screws/Bolts

Tools
Table Saw
Drill or Drill Press
C-Clamps
Optional: Chop saw or hack saw

Step 2: Cut Your Squares

Once you have your street wood, you should be able to determine the size and number of your squares. I recommend scaling them between 5" inches and 8" inches. If they are smaller than this they become too small to retain the detail of the original tags, if they are much larger they will become too heavy to stick to the magnetic paint.

BEFORE CUTTING, check your wood for any embedded debris. Nails, staples or other hardware hidden in your wood can cause dangerous kickback and injuries when using shop machinery. Be discriminate when choosing your street wood.

A 4 by 4 (16 total pieces) or a 5 by 5 (25 total pieces) grid seems to give enough versatility of different square configurations without being too overwhelming to cut.

Keep in mind that the thickness of your material will affect the weight of your squares, and thus how well your pieces stick onto the magnetic paint.

Once you have your width/height dimension determined, set up a fence on your table saw to that dimension. The fence is important to make sure all of your pieces are the same width.

After you cut your wood into strips, set up a sled on your table saw to cut the strips into individual squares. At this point, you can take a C-clamp and a scrap piece of wood to clamp a jig to your sled. Along the same lines as the fence, it will ensure all your squares are cut the same size.

Once your jig is clamped to your sled, you can begin cutting your squares.

Table saw basics and safety.

Step 3: Make Your Squares Magnetic

Buy your magnets depending on the number and thickness of your squares.

I used four 3/8"by 1/8" NdFeB "Rare Earth" magnets for each of my 7" x 7" squares. They were cut from 1/2" thick plywood. Thicker material may require larger or more magnets to get a sturdy stick.

Once your magnet dimensions are determined, you need to drill a hole into your squares where you will be gluing your magnets. This step is necessary to make sure your magnets don't break off easily through rough use or by mischevious users.

Your holes should be drilled to half the depth of your magnet so that once the magnets are embedded part of it is raised above the surface of your square. This will provide a better connection to the magnetic surface where the final grid will be mounted.

For my 1/8" thick magnets, I drilled holes approximately 1/16" thick. I used a Forstner bit in order to achieve a flat and square inner surface- standard drill bits leave a slightly curved surface which will prevent your magnets from gluing properly. I also set my depth using the stops on my drill press, in order to ensure that all holes were the same depth.

Once your holes are drilled, mix your 5-Minute epoxy and start gluing your magnets into the holes. I suggest waiting for the epoxy to set the full hour before testing the strength of your magnets; if you test them too early they may be pulled out of the glue.

Step 4: Cut Your Frame

Once your square dimensions are determined, you can easily determine the size of your frame.

For example, I used a 5 by 5 grid where each square had 7"inch sides. The overall dimensions of my grid were 35" inches x 35" inches.

The thickness of your frame should be based on the kind of material you are using and the way it will be mounted to the wall. I recommend using MDF because it is easier to connect using common hardware and limited machinery. Plywood can be used in the same way, but is less structural and will hold less weight.

Because I used plywood, I decided my frame should be 1 1/2" inches thick. They should be 38"inches long to include the dimensions of the frame AND a 1/2" tolerance for the squares.

Set the fence on your table saw to cut your 4 frame pieces to the desired width. A chop saw, hack saw or sled mounted on the table saw should allow you to cut the length down to size.

Decide whether you will be <a href="http://www.google.com/search?hl=en&lr=&defl=en&q=define:Miter&sa=X&oi=glossary_definition&ct=title">mitering or using right angles to connect your frame. If you are using a right angle construction, keep in mind that you will have to cut 2 of your frame strips shorter than the other two to achieve a perfect square.

Glue and clamp your frame edges together as a preliminary connection.

Reinforce this joint with staples, nails or wood screws.

Step 5: Magnetic Wall!

Once your frame and squares are ready, you will have to choose your urban surface to mount the Graffiti Jumble.

At this point you should have already bought magnetic paint additive, which is essentially finely ground iron particles which you add to a primer. The "One quart" size is enough to cover an 8' foot by 5' foot surface.

Mix the powder into the primer well and stir it up before painting the wall's surface; the particles will sink to the bottom if left to sit.

You will probably want to choose a place that is relatively easy to access because you will have to paint the surface at least 3 times to get a coat of magnetic paint strong enough to support your squares.

Also keep in mind the surface of the wall where you are mounting your frame. Wood is relatively easy to bolt/screw into using a standard drill and bit. Concrete/brick requires a high-powered drill and special masonry bits. Epoxy provides another option, but will require that you wait for the epoxy to set before your frame is strong enough to support your squares. Epoxy will probably not work on very uneven surfaces such as brick.

At least an hour is recommended between coats.

Step 6: Attach the Frame

After the 3-4 coats of magnetic paint have dried, you are ready to mount you frame.

The surface of your wall will determine how you mount your frame.

Wood is relatively easy to bolt/screw into using a standard drill and bit.

Concrete/brick requires a high-powered drill and special masonry bits.Masonry bolts must be used to attach to these surfaces.

Epoxy provides another option, but will require that you wait for the epoxy to set before your frame is strong enough to support your squares. Epoxy will probably not work on uneven surfaces like brick.

Step 7: Add Your Squares.

After your frame is determined to be secure, you are ready to stick on your squares. Place them inside the frame in a grid pattern.

Your Graffiti Jumble is now ready for its first tag.