Is TSP safe on wood if you plan on keeping the original finish??

Not recommended. TSP is a strong cleaner/degreaser. It can affect painted surfaces and stains. Not to be used around metal, it can corrode some finishes. It can etch glass. Basically used to clean wood or furniture to prepare for painting or staining.

I would go with warm soapy water, blue Dawn, instead. TSP will degrade the finish.

here is more info on using TSP I have used it for walls, paneling and cabinets without any problems for over 30 yrs just follow instructions

https://www.bobvila.com/articles/cleaning-with-tsp-trisodium-phosphate/#:~:text=Suitability%20for%20exterior%20surfaces%3A%20TSP,cement%2C%20wood%2C%20and%20roofing.

https://askinglot.com/is-tsp-safe-for-wood-cabinets

TSP is so strong that it will peel old paint from a surface along with the stains, TSP is often used for cleaning surfaces in the course of preparation for painting, particularly for exteriors. It removes splintered or flaking leftover paint that may impede the bond of the new coat.

TSP can be used to clean wood in particular to prepare wood to be painted, a substitute for TSP would be Simple Green.

Here is a link for cleaning wood surfaces:

https://cementanswers.com/can-you-clean-wood-with-tsp/

Hello. I think there might be better options. Have you considered krud cutter. Here’s a link

https://www.rustoleum.com/product-catalog/consumer-brands/krud-kutter/

It's usually used for cleaning before painting

I wouldn't. I'd use vinegar and water.

I use TSP substitute powder well diluted with water on my cabinets but be sure to read the labels well before buying or using.

Hi Debi, hope this link provides some information for you, I think you can use it

https://www.hunker.com/13420925/how-to-use-tsp-to-clean-wood