{"id":107006,"date":"2019-10-24T14:01:39","date_gmt":"2019-10-24T19:01:39","guid":{"rendered":"https:\/\/www.artofmanliness.com\/?p=107006"},"modified":"2026-01-11T12:40:23","modified_gmt":"2026-01-11T18:40:23","slug":"two-methods-for-homemade-invisible-ink-one-of-which-works","status":"publish","type":"post","link":"https:\/\/beta.artofmanliness.com\/skills\/just-for-fun\/two-methods-for-homemade-invisible-ink-one-of-which-works\/","title":{"rendered":"Two Methods for Homemade Invisible Ink (One of Which Works)"},"content":{"rendered":"

\"Homemade<\/p>\n

The story of invisible ink \u2014 <\/span>as detailed by Brett and Kate a number of years ago<\/span><\/a> \u2014 goes back millenia. Used mainly as an espionage device, militaries and governments the world over continually worked on ways to discreetly send messages between covert parties. <\/span><\/p>\n

These \u201cinks\u201d started as very simple concoctions in two primary categories: 1) an acidic liquid applied directly to paper or parchment, like lemon juice, vinegar, or even urine, which would then be revealed by heat exposure (<\/span>as in the gloriously cheesy <\/span>National Treasure<\/span><\/i><\/a>), or 2) \u201csympathetic\u201d inks in which some type of chemical solution acts as the ink, which is then revealed by the application of a different solution, called a \u201creagent.\u201d <\/span><\/p>\n

When invisible ink technology progressed in the 20th century, especially with the development of increasingly complex chemical solutions during WWII, the invisible inks of old became mostly a relic, and for us moderns, a very fun weekend experiment to do with our children.  <\/span><\/p>\n

My 4-year-old son Graham and I experimented with both types of inks \u2014 one of which failed and one of which was an astounding and surprisingly fun success. <\/span><\/p>\n

Let\u2019s take a look. <\/span><\/p>\n

Method #1: Acidic Ink (Lemon Juice)<\/span><\/h3>\n

In theory, the most tried and true method of homemade invisible ink is the simple application of pure lemon juice (or, as mentioned, a number of other acids) to a sheet of paper. After the paper is fully dried, you apply heat, and voila! the \u201cink\u201d is revealed. The acid eats the fibrous material and therefore burns more easily; when heat is applied, it browns the areas that have been written on. <\/span><\/p>\n

This is, by far, the most common method you\u2019ll see when searching the internet for how to make invisible ink. After trying it out, however, I\u2019m guessing that most of those writers and publishers never tried it firsthand. <\/span><\/p>\n

I definitely get the appeal of this method; it\u2019s as simple as juicing a lemon into a small dish and then applying that juice to paper with a small paintbrush or a cotton swab. No mess, no big cleanup. That\u2019s a huge positive, especially with kids. <\/span><\/p>\n

Unfortunately, after trying various heating methods, I could never get the ink to actually show up. Hair dryer, hot light bulb, I even held the paper above our gas range for a few minutes. None of it worked. Consequently, I\u2019m not buying Nic Cage\u2019s easy reveal in <\/span>National Treasure<\/span><\/i>.<\/span><\/p>\n

So I did some sleuthing and came to find that it takes quite a bit of time for the paper to actually burn and for your secret message to appear. Some folks reported holding the paper over a hot light bulb for upwards of 20 minutes! Others even <\/span>baked<\/span><\/i> the paper for a while. Those requirements are a hard pass from me. Plus, kids and heat sources just don\u2019t mix real well. <\/span><\/p>\n

After the initial excitement of embarking on a fun new activity, both father and son were disappointed at the lackluster results. <\/span><\/p>\n

So we hit the books (aka Google) again in search of a different method that would actually work. Turns out it took a sympathetic ink and a fun reagent to find success. <\/span><\/p>\n

Method #2: Water & Baking Soda + Rubbing Alcohol & Turmeric<\/span><\/h3>\n

\"Water<\/p>\n

Supplies\/Ingredients: <\/h3>\n