I had pencil writings on the wall from my childhood and this year I came back home and I found that my parents had the wall repainted with white paint. I should've taken a picture of these writings as they are part of my childhood memories. Is there still a way to look through the white paint for my pencil writings?
Yes, but it's not necessarily easy to do without specialist equipment. It's done by forensic document examiners and art historians.
we can retrieve under-drawings below paintings by looking at them in infrared light. This is because the carbon used by artists to make their under-drawing absorbs light at that range of the spectrum ... Ultraviolet light has often been used to look at faint text in medieval manuscripts,
Spectral imaging recovers faded or erased text by capturing details about the ink and the parchment at different wavelengths. And because different wavelengths of light convey information unique to that spectrum, traces of iron ink, for instance, appear one way in infrared light, another way in ultraviolet, and, perhaps, not at all in visible light. Multispectral imaging collects the different information and recombines them into composite spectral signatures.
Infrared imaging has been used to analyze old documents and works of art since the 1960s. But the equipment typically used by conservators for this kind of analysis is bulky and pricey; the systems can run more than $100,000. Falco has developed a hacked hand-held version —not as precise in resolution, but cheaper and more portable, making it possible to image paintings right on the walls they adorn. ... Falco can also jigger his camera to photograph ultraviolet light, which can reveal otherwise hidden details, most notably fluorescence.
If it's a couple of coats of emulsion paint, and stain blocker wasn't used, you could try with a close-up infrared and ultraviolet light sources (infrared LEDs are cheap and used for CCTV, ultraviolet is used for disco lights and insect killers) and see if you can detect anything.