Marking Pens ? Probably a stupid question

[Murphy625]

I'm cutting logs and need to mark the ends of them.   I don't want to guess or purchase the wrong type of marker for this.

What do the professionals use to mark the cut ends with?  Is there a specific brand or type of marker everyone generally uses?

I just need to write down about 5 digits.    Need something that isn't going to fade in the sun or be washed away by rain, and that writes on a chainsaw cut end.
Thank you

[Jeff]

Google log or lumber crayons

[doc henderson]

these are wax crayon type.  they also make holder that can go on a retractable lanyard.

[Frickman]

I have used wax lumber crayons, railroad chalk, and paint.  I purchase railroad chalk by the stick at my local hardware store.

[Old Greenhorn]

I use lumber crayons. They don't fade BUT the wood does and so readability will change over long periods. Get some different colors and see what works best for you. I use yellow on darker hardwoods and red on conifers, blue works well too. The crayon holder works nicely, but I also use a CH Hanson Pencil Pull, actually two. (I learned that trick from CustomSawyer) I have one on each of the rings on my suspenders. One has a carpenters pencil for shop work and figuring, the other has a crayon stub for marking logs. Both are very handy.

[Murphy625]

Thank you everyone!   

[thecfarm]

I've always use black. 

[BargeMonkey]

Crayons like everyone else mentioned, if your not doing a high volume. My normal log buyer has an attachment that goes on a spray can, makes legible 6-8" #'s and he's fast with it. Can see them clearly on a load I shipped in. 

[g_man]

I use the crayons too. In the winter they get hard and don't write so well especially on wet wood but I can make them work but you have to look close. The scaler at the yard uses a special paint spray, red or blue, like Barge mentioned and that seems to work very good.

gg

[Magicman]

I use DeWalt crayons in the Winter and Dixon in the Summer.  Temperature does make a difference.

[Stephen1]

I'm sawing some hardwoods now that I marked in the November with red crayon, I'm not liking that I can't see what # log it is. If I hit metal, which I do , I knock the price of the log off the next order. I buy my logs from an arborist and that's the deal we have. All my wood are yard trees. 
I'd like to switch to paint for the next load. What kind of paint? 

[Riwaka]

Developing high-end forest log marking for tracing log sources and tracking log supply chain security, log quality etc purposes. Beyond the bar codes and QR codes for individual logs stapled on and sometimes fall off.

Like the leather stamping tools.

From simple handheld log-end marking tools, to log-end hammer stamps for logs to log-end stamps that fit on processor heads (in developments) 

Deeplai - Polish Company.

Youtube Deeplai - example with the adjustable log-end hammer stamp & handheld electronic device. 
https://youtu.be/rTJKA9LzC9w?si=kfw_93RL20hiiatO

https://www.deeplai.com/technology/dms/    (manual marker stamps that work in a frame)
https://www.deeplai.com/technology/dma_s_a_automated/
The automated marker is designed for hard wood marking based on Dcode. The levels of hardness require a focused solution foreseeing the species specifics.

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Figure out the above to be cheap enough for the woodlot level?