This is what Tom Bihn Inc says in the FAQ:
How do I clean my bag?
We recommend hand-washing your TOM BIHN bag with a mild detergent — environmentally friendly dish soaps work well, but as always, with any soap, test it on a small, inconspicuous area of the bag before you use it on the entire bag. (PalmoliveŽ and DawnŽ soaps may be too harsh!) Fill your sink or bathtub with warm water, add a little soap (a little goes a long way), and let the bag soak for a half hour. If there are visible spots of dirt, gently rub the area with a washcloth, or you can apply a little soap directly to that spot and let it soak. Rinse your bag thoroughly (this is a lot easier if you've only used a little bit of soap) and lay your bag flat on top of a bath towel to dry.
Methods we DON'T recommend:
Having your bag dry-cleaned or putting your bag in a washing machine or dryer will void the guarantee and make your bag look funny. We don't want either of those things to happen. Your TOM BIHN bag can last for years. The fabrics we use to make our bags are treated with a water-resistant coating, but over time, that coating will start to dissipate. If you live in a rainy climate like we do, we'd recommend treating your bag with Nikwax after one year of use.
Below is the answer I gave you to help, I then realized that there was a topic about it on the FAQ.
The Crew also know as Customer Service Extraordinaire is wonderful, email, message or call them if you want to find out what the best soap is and more information on cleaning your Smart Alec and how to apply Nikwax, the water repellent recommended by Tom Bihn
Wash the bag with eco friendly dish soap, the kind used to handwash dishes. I use, one or two drops of 7th generation free and clear, after soaking the bag in plain cold water, the drops suds and dislodge whatever dirt was there. There is no need to scrub.
Do not put it in the washing machine!!
Fill your bathtub or your sink with cold soapy water, immerse the bag, rince it thoroughly, let it air dry on top of a towel.
After it is thoroughly dry, I let bags air dry a day or two, depending on the warmth and humidity in your area.
Then, you can apply Nikwax which Tom Bihn sells.
https://www.tombihn.com/products/nik...nt=16645280391