So over the past few weeks i have been involved with a project called A Shedload of Science in partnership with Glasgow Science festival (links to their websites below) and its given me the opportunity to work with some materials i haven't worked with before. One of these is Thermochromic pigment and we will be using this today to make a colour changing heat sensitive phone cover.
Now before you think "Thermochromic pigment? sounds expensive and hard to come by." Its pretty affordable and available at online retailers. We used Maplin which was £2.99 + P&P for 5ml which you mix in with paint so you end up with more.
Step 1: Materials and Tools
I'm using magenta here another thing to note is because we are mixing it with acrylic the end colour will be lighter but i will go into that more in the next step
I'm using white here as the colour change is more dramatic.
hard phone case.
I'm using one bout from the Pound shop so it doesn't need to be expensive.
I'm using spray on but a thin layer of any clear coat varnish would do the trick
Sandpaper. fine coarseness
Small container to mix the paint and pigment in
Step 2: Mixing Your Pigment
As mentioned before because you are mixing it with acrylic paint you are going to get some colour change. as i am using white with magenta its lightened down to a more pinky colour pink. Take this into consideration when mixing your paint/pigment as you can get some nice colour changes, For example mixing red pigment with yellow paint will give you an orange paint that turns yellow under heat or blue pigment with red paint will give you a purple paint that turns red.
There doesn't seem to be any information about proper ratios to use when mixing pigment and paint but i have been using a rough ratio of at least 2 parts pigment to 1 part paint. (EDIT: I have since found out the recommended ration is 4 to 1)
I have dabbled in using the pigment "straight" but it doesn't seem to work as well without the acrylic as it goes a grey in colour and when you can only get it in 5ml shots i could see it becoming quite expensive
To mix it I put it in a small container and mixed with the brush.
Step 3: Prep the Case
To prep the case i gave it a rub over with the sand paper to get rid of the glossy feel and help the paint stick. once i had gave the outside a sanding i gave it a rinse and dried it off.
Step 4: Painting Your Case
Yup, its that simple.
I ended up giving it 3 coats letting it dry between coats*, mainly as the pattern kept showing through (once the phone is in it it doeskin show through as much but as i use my phone to take the photos you can see my conundrum). the photo above is after 1 coat
Once dry I gave it 2 quick coats with the lacquer waiting for it to dry between coats*.
*You can speed this up with a hair dryer but don't freak out when the colour changes, it's supposed to do that remember ;)