Complete List: How To Make Invisible Inks

Posted By Robert Rake    

After I filled dozens of invisible inks products to my eye marked cards stock, I suddenly realized a fact that I haven't done anything scientific experiments on my own, not done either with simple rainbow maker or the spinning ice dancer, none. Although I myself as a marked cards manufacturer has produced a lots of invisible inks for marking playing cards via assembly lines in my own factory, but here is a great idea of me being working on homemade invisible inks all by myself, you know, just for science, or may be for fun, so does it sound a bit interesting?

So how to make invisible inks at home just use some regular daily stuff, without expending a high price to collect household objects? While I was searching the guidance to this experiment, surprisingly to me, there are already a heap of howtos online and every of them speaks clear of some part of the story, and each one is big time useful to make one example out. However, at some points, I came up with an idea about collecting and demonstrating all the methods and materials, put them together as an integration, a whole complete list which can make people who are interesting in this making process be more comfortable to find the corresponding materials and tools for themselves. Cause I know big fat failures happen when some parents and their children try to deal with it, so I hope this post might give them some good advice and finally make it on their own.

So how many ways or methods on earth to achieve this scientific experiment? Actually according to my research, there are totally four ways, the three of them can be handmade and last one need some UV lights. The fours are here, classify them by reappearing means:

  • Heat
  • Paint
  • Indentation
  • Chemical inks or industrial inks

I'll go one by one.


By heating the paper with unseen messages, you finally can see the secrets. Check the video below to have a initial impression.


  1. Prepare organic matter liquids such as lemon juice or milk, add some water mixed with them in a container like bowl.
  2. Using a writing tool such as a pen or thin stick to daub some of the liquid compound we made.
  3. Write whatever words or pictures you desire on a white piece of paper, and wait for it being completely dry.
  4. Heating the white paper uniformly via holding it close enough to a glowing device like light bulb, but try to be careful not to set anything on fire. Eventually, if anything done with no wrong, you should see the previous invisible marks.

Substitute of Materials

You may lack of lemon juice or milk at home right now, all though that's shock to me, but still in this case, you have plenty of stuff can be served as inks. The substitutes: vinegar, any fruit juices(orange juice, apple juice, grape juice, etc), onion juice, honey, wine, corn starch.

Replace The Pens

Don't tell me you have no regular pens left, nonetheless that's all right, I still show you a bunch of stuff you can use to replace your unwanted pens. Those are: thin sticks, Q-tips, cotton swab, paintbrush, toothpicks, feather, quill-pen, fountain pens, chopsticks, or your fingers and nails, just any objects with sharps.

Science Principal Behind The Curtain

Liquid stuff like juice or milk, in chemistry, they are belonged to organic substance, organic liquid in liquid form. When they are being heated or burned, the Redox chemical reaction happens with them and electronegative elements dioxygen(aka oxygen gas), the oxidation and reduction reactions would turn organic juice into deep color, for instance, lemon juice will become brown. So previously, those invisible codes are hidden, then after that, they show up again by activating them via changing their chemical forms.

Heating Devices

Well, light bulb should be a safe heat addition appliance, but only too slow to emerge inks out. There are heating devices for your choices, some come from me as well as some come from other experimenters, it is to be said that heating paper covered with a rag up by iron has incredible effect. But still those things you can pick up as you will: sunlight, lamp, stove and oven with certain temperature, toaster, hair dryer, matches, lighters, a cup of hot water(by surrounding it), barbecue, bonfire(where are you), OK, that's enough. I can go on, but you get what I mean.

Safety Warning

Attention, parents and little readers who read this article, if you plan to put your hands to this heating method, you may wanna be careful about the flames. Do not ever make things too dangerous while using any heating devices, watch out fire!

Other Notes

The purpose of putting water to stir the juice, is to dilute the juice to make it even more slight and light-colored, makes it more unapparent to naked eyes. Acid liquid like lemon juice has an impact with paper, I think it is also should be considered.


By painting other materials on the paper you just wrote, that will display the concealed inks from sights. So not need for any glow stuff. Watch the cute video below to get this concept.


  1. Prepare raw materials like white crayons and white candles, if you like baking sodas, then prep a corresponding share of water as 1:1 as well.
  2. Draw anything images or words with the crayon pencil or candle, or use a writing tool to daub the soda mixture and then write on the paper.
  3. Wait until the invisible inks dry fully.
  4. Bring a paintbrush or something else has the effort to paint the paper with watercolors, and when you do this, the inks show themselves.

Substitute of Materials

If crayon is not your first choice, then go and try: wax, white chalks, polish, pastel, glue, grease, china marker, etc. Things are going crazy, you see the colored materials here, because sometimes you don't have to record secret writings only on white paper, but try other colored paper, or even other things that can be wrote on.

Replace The Pens

As you see, the crayon pens are blunt, not as gracile as the pens I mentioned on the heating section. This time you are dealing with wax stuff, so bring a paintbrush or writing brush, toothbrush, hairbrush, whisk, mop, just anything to paint watercolor or pigments onto the paper. Whew!

Science Principal Behind The Curtain

The trick behind the scene is the science fact of water colors resist to crayons, it means crayon will repel the watercolors on the top of them away. It totally makes sense to make invisible inks using white crayon writing on white paper, at the very beginning, the white wax are not visible to the eyes, but later you paint different colors on that white paper, the crayon stay put as white style, but surrounding parts will be stained as what water color you choose. So immediately, the invisible crayon inks stand out, no other complex devices needed. And as I said above, you don't have to stick with white background, just put any color to corresponding background and then apply with other colored watercolors in order to change the backdrop would approach the same just as white ones.

Other Notes

See, this method don't make you to warm up your hands, and better if only you are student who learn painting because you already got the painting kits. By the way, you do not need know anything about resist mechanism, but hold the paper to sunlight through window, you can see the marks. Because after all, the wax are different from paper, and lights would tell you the gap.


Do you have a coin, have you ever tried one coin and one paper art form? Well, may be it's too fancy to call it an art, but it is something kids do when they are exposed to new things. Rest a white paper on a dime, use black pen smear the circle area, without any painting train before, you become an artist who can draw head portrait in seconds. We all like painting and drawing pictures in some levels, it's definitely fun for kids.

But how to apply to invisible inks with indentation? This one is simple, and easy to apply with just several papers and a normal pen. In this case, neaten some papers together, write top secret notes forcefully onto the first paper, but try not to tear it up though. When finished, remove all of them except the last one, now shade this paper with your black color pen, the indiscernible inks gradually come out.

How is it that? Simply because the indents exist on the flat board, and when you are drawing, you surely miss most of indents, all the parts of relative convex would be painted. That being said, color discrepancy lighten our human eye's vision, and if not we hardly see any different.

Chemical Inks or Industrial Inks

Here is the session for invisible inks marked cards or even spies and agents. For marked cards, card cheater use invisible inks to mark playing cards, and read the perdue cheating codes through infrared sunglasses or contacts. For spying, or top secret messages transmitting, those secret inks usually need to be detected by optic lights or other physical and chemical methods. These are more practical and realistic, not for playing around, but for poker money or important messages.

The ways to make those invisible inks readable are various in many aspects, one can give a whole book of talking about them. I only enumerate some here to enrich this list as much I can:

  • Infrared radiation
  • UV light(ultraviolet)
  • Black light with violet filter
  • Night vision
  • Special chemical portions
  • Try illuminate the surface with strong beams from many different angles
  • Rinse in the water and then make it dry
  • Dust some powdered charcoal on surfaces

Creativity Ideas On Topic

So after wrote about so much things, except making your own DIY invisible inks, what others thoughts do you have in your mind? To be creative, to be practical, and to be awesome, to employ what you make. May be try:

  • Make an invisible ink note to your best friends
  • Write your diary in this way to keep private
  • Host an invisible painting show
  • Produce and design a pen filled with invisible inks
  • Educate your children and stimulate their interest to science(should do more experiments instead only one)

Wow, I am impressive by myself, that is really holy crap of a whole complete list, well, they said hard work well paid, I hope so. But there are something still should be told, one of them are the inks are not going to stand long time, it will expire after been frequently used or exposed in the air for a long time. On the other hand, do not record any important messages with normal juice or inks, all your work will be in vain, use chemical inks instead.

And one more ethics problem, as the famous saying from Spider Man goes:"With great power comes great responsibility", the invisible inks clearly have the potential power that could be misused in many fields to do bad things, like businesses, laws or countries. As the same problem with super power, if you use it against evil, you are hero, or you are one of the minions. It is really up to the users and occasions, so be clear what is the deal and then decide.

Anyway, the original purpose of making this list is for homemade science experiments, for fun, for kids, and for DIY. I hope this integration would be helpful for someone digs into this topic and really wanna a try. Several important links listed below are the sources and materials that help me wrote this post, you may find some more interesting information and discussions there. And if you find my post are lack of something or obviously exists some mistakes, please feel free to point out and let me know. I will keep updating this whole list if something new or correction shows up.

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