New here! Problem with color transfer even after shellac - Woodworking Talk - Woodworkers Forum
 
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post #1 of 7 Old 12-24-2015, 11:57 AM Thread Starter
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New here! Problem with color transfer even after shellac

Hi, this is my first post. I am not a woodworker (yet!) but just a crafty mother who wants to learn how to make wooden toys and blocks. I like the idea of using stuff around the house, so when I saw an article about dyeing children's blocks and toys with food coloring, I got excited and decided to try it. I have a problem, though, and I'm not sure if it's because I used food coloring to tint my wood blocks, or if there was a problem with my methods. I need to fix these blocks! (and btw I probably will never use food coloring again).

That was the short story. Here's the long story: I was trying to salvage some OLD chewed up building blocks for a children's community setting in which there is not money to buy brand new blocks. They were natural, no finish at all, and I assume they are pine based on pictures I've seen on the web of the wood grain. They were filthy, dry, and chewed on the corners. I washed them with soap and water but did not immerse them. I thought they were pretty dry (a couple of days later) when I started working with them. I sanded them to get the dirt stains off a bit better, and also tried to sand the corners to improve them. Since I have no tools, I really couldn't do much more. Because the wood was not really very pretty, I opted not to go with a natural finish and wanted them to be colored instead.

The instructions for food color dyeing said to mix the food coloring with rubbing alcohol before brushing on. I was using powdered dyes from a bake supply shop (because the colors were more brilliant) and the powder dissolved better in water, so I did that first, then added alcohol. The one color that I used liquid food color instead, and therefore did NOT use water, was green and it is the one set of blocks that do not transfer as much color to my hands (they still do a tiny bit), so that may be a clue - I don't know.

After the blocks were dyed and dried for a day or so, I applied a water based lacquer. That made them all nice and shiny, but despite three coats (about three hours between coats), the color continued to transfer to my hands when I rubbed them.

First question, why??

After a little research online, I decided to try some shellac from a spray can. After a couple of coats, a couple of hours between coats, the color transfer problem was lessened, but still a problem. One thing to note is that when I rub them with a cloth, color does not rub off. It only seems to come off onto my HANDS.

Back to Google to figure this out. Old shellac was one problem mentioned so I checked the expiration date on the can and sure enough, it was about 10 months after expiration. However, the shellac DID dry fine - maybe the slightest tackiness but not much. Back to the store for a NON expired can of shellac, and gave the blocks a coat of this. After a few hours, I picked them up and there was still color transfer to my hands, but much less than before. I was rubbing them pretty hard because I want to be sure they don't bleed color onto children's hands.

Second question: are these blocks a lost cause? Was the food coloring as a dye choice the mistake? Am I not giving the shellac enough time to set? (everything I read online says shellac is dry and set by one hour after application). I need the color on these blocks to be set once and for all.

Any suggestions or ideas about what might be going wrong? Like I said, with the one coat of non expired shellac, the problem is less. Is it just a matter of putting a couple of more coats on?

Thanks!!
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post #2 of 7 Old 12-24-2015, 02:08 PM
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I like your ambition on this.

The simple answer, based on my experience, is to use a water based dye for the wood, and an oil based clear coat. Don't use alcohol in your dye, and don't use a water based dye with a water based clear coat. Both of the latter will allow the color to get into your clear coat, and you have experienced those results.

For water based dyes, I usually use the Trans-Tint line available at woodworking stores. Food coloring may work (I've not tried it), but don't add alcohol. You can also try that RIT clothing dye that you can get at grocery stores, drug stores, etc.

By the way, I never had much success with shellac - I got color transfers as well, so I don't use it.

Alternatively, you could paint the blocks. That might be simplest.

Finally, be sure to do a test on only one block, to make sure whatever you're doing works. I suspect, that if you take a dyed block, and add a clear coat to it, that you should be able to rub the clear coat while wet with a rag and not have any color come out into your rag. If you get color, then it's not working. I know using a water based dye and an oil polyurethane, that you won't get any color transfer.
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post #3 of 7 Old 12-24-2015, 02:35 PM Thread Starter
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Thanks for the advice! So, are you saying that if I were to get an oil based clear coat, I could apply it over what i've already put on the blocks? Do they make oil based clear coats in a spray can? Or would I have to brush it on? Lastly, would an oil based clear coat be safe for toys?
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post #4 of 7 Old 12-24-2015, 02:44 PM
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maybe too late to this party but ...

If I recall, the Rit dyes required hot or boiling water to immerse the clothes in for the dye to work. You may try dunking the next batch of blocks in that sort of solution and just leave them as is afterward. I would also try to get more blocks at a Salvation Army type store and make more "refurbished" ones.

As far as a safe childproof finish you would have to research that a bit. I think spray lacquer, fast dry would be OK, but I donno? Shellac is probably OK also, since it's made from bug poop. I don't know about polyureathanes or oil/petroleum based finishes. Browse the spray paint aisle at your home store and read the hazard properties on the cans . There is a MSDS list on the hazards you can probably search online for.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #5 of 7 Old 12-24-2015, 02:46 PM Thread Starter
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Thanks Woodnthings, the reason I chose shellac is because it is considered safe for kids' toys. I thought it would work!
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post #6 of 7 Old 12-24-2015, 07:26 PM
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Quote:
Originally Posted by PattyG View Post
Thanks for the advice! So, are you saying that if I were to get an oil based clear coat, I could apply it over what i've already put on the blocks? Do they make oil based clear coats in a spray can? Or would I have to brush it on? Lastly, would an oil based clear coat be safe for toys?
I don't think that putting an oil based clear coat over what you have would work. I think once the alcohol is in the mix, that will allow the color to bleed. I think if it bled into the shellac, it will also bleed into the oil. Of course you can try it on one and see what happens.

I think you can get minwax polyurethane in a spray can. It's more expensive, though, than just buying it in a can. You could also use the wipe on variety. Here are one or two that should work:

http://www.homedepot.com/p/Minwax-1-...3005/100137867
http://www.homedepot.com/p/Minwax-1-...0900/100376148

I have no idea if it would be 'safe' for toys. When I was a kid, we used to eat lead paint flakes for breakfast (of course, with sugar), and I turned out OK!!

I think you could use RIT at room temperature. I have in the past, and it worked OK. Maybe for clothing it needs to be hot to penetrate well, but I think you'll get a decent color at room temp.
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post #7 of 7 Old 12-25-2015, 03:01 AM Thread Starter
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An update - I waited overnight and checked the blocks this morning and so far, no color transfer!!!! Maybe they just needed that last coat of shellac (not expired) and a little more time to sit a bit. I haven't yet tried touching them with wet hands. I'm afraid to try it.
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