I have told you about several methods for creating a wood stain in vibrant colors using liquid watercolors, and told you in the same breath that this method isn’t to be used for children who still mouth things, because it’s not waterproof.
I have told you about several methods to seal wood to waterproof it, but warned you that these methods aren’t eco-friendly, because there isn’t an eco-friendly way to completely waterproof a toy like this.
And yet, my friends, you still contact me all the time to tell me that your wood stain isn’t waterproof, and to ask me what eco-friendly method you should use to waterproof it. Mostly this is because you want to make something beautifully colorful for your small child, who still puts things in her mouth, and you don’t want to use a polyurethane sealant, because you don’t want her to put polyurethane in her mouth.
Oh, my gosh, Friends!
I appreciate what you want to do. I really, really, really do. You want to give your children the best of both worlds: you want them to have brightly-colored, vibrant toys, and you want those toys to be completely natural.
Until your children are old enough to stop putting things into their mouths, however, you are going to have to pick one.
You can stain or paint your children’s toys so that they’re bright and vibrant, but then you’re going to need to seal that wood stain or paint using a clear polyurethane sealant. Maybe an epoxy resin, if you’re feeling adventurous. Your kid can put the toys in her mouth, but she’ll be licking the sealant, not wood.
You can make your children wooden toys that are perfectly natural, and shine them with a beeswax polish, but anything that you paint on or rub in will come off in your child’s mouth, even the beeswax polish. Permanent marker will stay better, if you’d like to add some details. If your kid can keep her toys out of her mouth, she can play with stained wood forever and not experience any bleeding.
Some readers have had some success with vinegar, although as vinegar would really just serve as a rinse agent here, it won’t necessarily stop the bleeding. As you can see in the top photo, if I place the dyed mosaic cubes that my kids play with every day in water, all the wood stain bleeds off of each one.
If you deeply desire a stain that is vibrant but won’t bleed, you could always try making a big batch of homemade alcohol ink, but then your kid would be putting alcohol in her mouth, so there’s that.
So what can you use vibrantly-dyed wood for? Interior decoration projects. Furniture that will be sealed. Indoor toys. Building blocks. Holiday decorations. Anything, if you seal it.
tl;dr: If you need it to be colorful AND waterproof, you need to seal it. Otherwise, skip the color and just let the kid gnaw on the natural, wood-colored wood.