How to Create Lumi Inkodye Tee-Shirts!
In this Instructable I'm going to show you how to create cool looking Lumi Tee-shirts, but I'm also going to reveal some lessons learned. I'm hoping you can avoid a few of the mistakes we made in our first Lumi adventure.

What are Lumi T-Shirts?
Lumi.co is a website that sells a nifty type of ink that is used to create images on cotton, linen, silk, rayon, canvas, and any other natural & absorbent fiber. The process is similar to film processing in that the ink is sensitive to the UV rays in the sun. You create a negative of an image, or us objects to shadow your material, expose the dye to the sun and viola! you have a wonderful and unique design. Simply wash the fabric and now your print is permanent, no more developing and fading in the washer!

Let's Get Started! What materials are needed?

Lumi Starter kit from http://lumi.co/collections/supplies - includes Inkodye for at least 4 shirts, Detergent, Roller and Instructions.
Light colored 100% Cotton material (I found inexpensive blank shirts at the local Hobby Lobby)
Painter Tape - to line the edge of the area to be colored...optional depending on the look you are going for.
Pins - straight pins or thumbtacks (be aware that thumbtacks can leave a shadow effect on the final print
Foamboard or Cardboard to put behind the front layer of the tee shirt.
A source image - Convert an image of your own to a negative, or use the Lumi app and order a negative from Lumi
A washing machine - washing stops the developing process
Sunlight - UV rays from the sun (or a highpowered UV light bulb) develop your print

Step 1: Step One, Create Your Image

Create a Negative of the Image you want on your Shirt

If you are an iPhone user, Lumi provides an app that can be used to create Lumi ready negatives, and even optionally order a negative (for a small charge)
Alternatively you can follow guides on Lumi to change one of your own images into a negative. I have an Android, so basically that is what I did...following these steps:

I took a picture of the a Vintage Robot using the Android app Camera ZOOM fx
I used filter options in the app to convert my robot to black and white and reverse image
The black on the image wasn't really dark so I used a Windows based photo editing tool PaintShop Pro to darken in the already black sections. Since then I've also used the Grayscale and Negative Image options in PaintShop Pro to get a similar effect of any images.
I printed the image on a laser printer...and found (as recommended in the Lumi guide) that it worked better when I used 2 layers of slides.

Step 2: Prepare Your Shirt

To prepare your shirt for the dying process, all you need to do is:

Insert a piece of foamboard or cardboard inside the shirt to prevent bleeding from front to back
Use painters tape to mark off the area where dye is to be applied
Have pins ready to pin down your negative
Make sure for the next steps you are not in the sunlight

Step 3: Roll Out the Dye

Apply the Inkodye

Remember for these steps you don't need to work in the dark but be sure you are out of the sunlight and work quickly.

Apply the dye - Shake the bottle well for at least 10 seconds before using. We used either paint brushes, foam or the supplied roller to apply the Inkodye and found the roller to be convenient and work the best. (Note depending on the look you are going for other options are available, spray bottles for example)
To the area targeted - Roll the dye on the area you have targeted (be careful to not hit other spots on the shirt). The dye should go on like water with little or no color at this point.
Pin the negative in place, we used thumb tacks and found that the more pins the better (being careful to not leave shadows), with fewer pins, the negative tends to bend away from the material letting light leak in) (Pro tip: use a sheet of glass instead of pins to hold the negative down.)

Step 4: Expose the Design to the Sun

Exposing your design

This was a super fun step, just pick out a sunny spot and lay your prepared shirt out. The Inkodye is sensitive to the UV rays in the sun and actually begins developing in that the color appears stronger the longer it''s exposed to the sun.
It's handy to have a timer and start it at this point...depending on the sun, the design should start to show deep color around 10 minutes, especially if you are working in the prime sunshine of 11am-2pm
Bring the design inside and remove negative

Stop the developing process

Wash your shirt with the supplied Inkowash soap. This is a strong detergent that will remove the excess dye and prevent you from ending up with an over exposed design.
Use the Hot cycle, ideally wash the shirt alone and wash it twice.

Step 5: Viola We're Finished (and Lessons Learned)

The Finished shirt comes out of the wash - Yay!

Things we learned in trying the Lumi process for the first time:

Read the instructions and follow the Lumi Guide (we didn't get this step wrong, but I figured I should list it :-) )
It's reallyimportant to be out of the sunlight when applying the dye...we thought we were out of the sun when we applied the ink in the shade...was not a good idea...the ink started to develop as we were brushing it on.
Use the supplied sample material and negative to be sure you have the process down pat. We were worried too much about running out of ink and really didn't notice the sample negative...well there is more ink than you need for the recommended number of shirts and it would have paid off to try the sample negative before using our new shirts. Things worked much better on my second attempt at this process.
More pins are better - it's really important to have the negative flat against the material to avoid light leaking in (pro tip, use a layer of glass to hold the negative down)
Use two layers of negatives - If you print your own negatives, it seems to work better to use two layers to avoid light leak
Be Careful - it's easy to drip dye or roll dye out of the lines....you'll be sorry if you do that cause you'll have a blotch of color where you don't want it.
Have fun! We didn't get this step wrong either!