Baby-safe Food-colour Stain for Wood: an Experiment

I'm very committed to using food colouring to stain wood for children's toys. However, they tend to bleed their colour when wet baby mouths chew on them - not a nice quality in a toy.

This trial is based on make-baby-stuff.com's articles about non-toxic paint for baby toys where the only option I found viable was food colouring (because acrylic can flake off, milk paint requires specialized products that I don't have, and water colours are too light in colour for me).

Make-baby-stuff.com suggests several natural wood finish ideas that I experimented with here over the food colouring.

Spoiler's alert: Shellac Finish and Sealer wins.

Step 1: Beeswax Trial

This whole thing came about after completing my rainbow stacking toy for my nephew (see my instructable)

I had used Clapham's beeswax salad bowl wax to seal this toy.

It didn't work - see photo 2.

I went back to the drawing board and tried different food colouring combinations under the beeswax. I reviewed Amalkhan's instructable where they used rubbing alcohol. I also found online reviews suggesting mixing vinegar with the food colouring.

I tried all of these suggestions under the beeswax to no avail (not shown here). In the next step I'll show you my second set of trials with these different processes.

Step 2: Tung Oil/Citrus Solvent Trial

Out of all of the oils on the make-baby-stuff article, Tung oil is cited to seal "very well".

I decided to try just one oil (due to cost) - so went for the best review.

For the food colouring stain, I tried:

1. No additive
2. No additive, sanded after colour applied
3. Vinegar added
4. Vinegar added, sanded after colour applied
5. Rubbing alcohol added
6. Rubbing alcohol added, sanded after colour applied

Over all of these combinations of food colouring, I applied 1, then 2, then 3, then 4 coats of the tung oil/citrus solvent blend. You are meant to apply until the oil pools on the surface of the wood - and I went coats past that stage.

Although most of the sanded options stood up to the HAND TEST (does the colour rub off on my hand), none of them stood up to the CHEW TEST (does the colour rub off on my lips).

Conclusion: it doesn't matter if you add something to the food colouring, it is only the sealant that matters.

Step 3: Shellac Trial: the WINNER

The previous trial was disheartening, to say the least.

I decided to one-off it with the shellac trial, as it didn't seem to matter if the food colouring had additives or not. I also decided not to sand after applying the colouring as it significantly decreases the vibrancy.

To my surprize: The Shellac passed both the hand test and the chew test with only one coat.

Shellac wasn't my first choice as there might be a possibility of an allergy risk (here is the direct quote from the make-baby-stuff article):

Shellac - Not many people use shellac any more but it is a natural option. Made from the secretion of a lac insect in Thailand. Pros: Natural varnish and dries fast. Cons: Possible allergy risk for children's toys and has a short shelf life. Also not vegan.

A different blog states that Shellac is completely safe:

Shellac and Lacquer are evaporative finishes, i.e. they dry with no chemical reaction. When an evaporative finish is completely dry it is also completely non-toxic. In fact, shellac is often used as the hard outside coating on candies and pills.

All I can say from this experiment is that it works. I'm interested in hearing the instructable community's opinions on the subject.

Comments

[antioch]

Nice, and good research although food coloring has a history of unpleasant incidents. I prefer natural food colors.
That blog's thread about shellac safety is far from trustworthy, scientific or trustworthy:
"Shellac and Lacquer are evaporative finishes, i.e. they dry with no
chemical reaction. When an evaporative finish is completely dry it is
also completely non-toxic."

I can't see the logic, there's nothing conclusive about what something that dries without a chemical reaction should be non-toxic. One has nothing to do with the other.

So far I had success with juices (beetroot, walnut husk (bitter), raspberry), red wine and curcuma. Later on I applied 2 coats of vegetable oil (olive oil, linseed oil or whatever I could find in our kitchen). The olive oil adds one hell of a glow, in my opinion.

[Loblaw]

Natural food colours would be even better. Did you find that you could stain wood with them without it rubbing off?

Agreed that the blog might not be the best - although the make-baby-stuff article indicates that it should be safe in most cases (unless the child has an allergy). Do you feel that shellac is not baby-safe?

[antioch]

I wouldn't rely on my feeling in these matters, although I assume there won't be much to it beyond the allergic reactions. But very little research has been done on shellac, other than a few unpleasant lab tests on animals. It's probably more or less safe but all in all I don't like 'more or less' and I don't like the dirty background of it and the idea of an allergic reaction on a baby's lips puts me off.

http://www.webmd.com/vitamins-supplements/ingredie...

http://www.bibra-information.co.uk/downloads/toxic...

Staining with juices and wine worked great, yes, beautiful colors, and I enjoyed experimenting with them.
Obviously dark wood is hard to stain.
And unfortunately I never tried salivating all over it and then see if it
could stain the carpet, heh. But after applying the oil there was no
chance to get it off. If you wanna go pro you can heat and mix the oil
with beeswax for a great sealing finish but I never felt the need. Lots of info out there on the web:

http://blog.diynetwork.com/maderemade/2013/06/12/c...

https://www.pinterest.com/explore/natural-wood-sta...

[licheness]

Thanks for all the info! I have used food colouring and koolaid for dyeing protein fibres like wool and silk, and they bond really well to the fibre using vinegar as a mordant. Wood is cellulose, so I'm pretty sure your koolaid/food colouring dye is only staying on the surface, rather than bonding with the wood fibre, and, as you discovered, you then need a good sealant to keep the colour on the wood.

I had two ideas about other experiments you could try:

First, you could try to get the koolaid/food colouring dye to bond to the cellulose fibre so it doesn't come off as easily. Maybe, if you use a premordant of tannin, to first bond with the cellulose, and then use a potassium aluminum sulfate mordant to bond to the tannin, it will in turn form a really good bond with the food colouring.

Another approach would be to work with a material containing protein, like antler or bone to make your toys, and then see if the food colouring/koolaid dyes, used with a vinegar mordant, will create a good bond. If that works, the toys should not lose their colour, until the child (or dog) chews them...

Let me know if you try either of these. If I end up doing these experiments myself, I will write up an instructable and share my results!

[Loblaw]

Oh yeah I'd be really interested in your experiments! Let me know if you decide to go for it!