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Building Tips and technical articles. => Paint and finishing => Topic started by: Chancey Chorney on November 20, 2015, 10:43:58 PM
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Hi there. After reading about adding talc to dope, it appears a lot of mention of unscented talc. Also, as I read the regular talcum powder from the store works as well. But I would just like to ask where one would find such talc as unscented? Or is it available in the same stores as the other, just that I was not looking for it? Thank you.
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Talcum powder is typically cornstarch. Powdered rock talcum, the real stuff, is almost impossible to find. Cornstarch is cheap, and probably already in your kitchen.
Phil
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I've used baby powder for years. The label says its talc. Where can't you find it? If you are sanding almost all of it away except for what is filling pores I can't think weight is much of an issue.
Dave
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We used to get it from Tap Plastics. PTG now recommends http://www.soapgoods.com/Talc-Powder-White--p-1172.html?gclid=CL7t7cXtn70CFQNufgodbbMAow .
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I'd think 4 lbs would last for a bit.
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OK, you got me. I have read bottles of "baby powder" which is corn starch, several brands, and in the house. I do not have actual "talcum powder" in the house, but I do see it is available.
I have used kitchen corn starch with very good results. I have also read horror stories of the perfumes interacting with paint. I have never encountered those problems using corn starch. I never used baby powder to find out if it would be a problem with the paint.
Phil
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I've never mixed anything with dope except thinner, even years ago, but I know guys do this.
Does it "fill" the grain, Soak in? Or "float" over it?
Maybe I should give it a try?
Charles
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I'm using an off brand baby powder right now but it says 'compare to Johnson & Johnsons. You can read the label. The fragrance seems only to make the task more enjoyable- until buried in the dope. Never found any issues with using it.
Charles the talc has a weight, though small and does not float. It soaks into pores and settles onto the surface. Only once I tried to do this with micro balloons. They float! They all rose to the top and were immediately sanded off. Nothing went into the grain/pores. I've never tried corn starch so I don't know the result but I'd guess it's more like the powder.
Dave
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I just happen to be doing exactly this tonight. Thought I'd get an idea of the weight. To a quart of dope I'd add about 1/4 cup of powder. I weighed that amount of dry powder and got 1.5 ounces. I'm surprised it's that much but if we can sand off at least 80 percent of it then I think it's reasonable.
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The grain gets filled very quickly with corn starch in dope. One coat of (by volume) half and half corn starch and dope is enough to make a surprisingly smooth surface after paint.
Problem I have encountered is if finishing with different paint types, specifically enamels, the enamel resists other solvents, but does not block them so the dope softens and sloughs the enamel!
Phil
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Thank you all for the help. I think I will take the cornstarch route as I do have it readily available.
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If you're looking for talcum powder, check at any "Army Surplus" stores you have nearby. They are about out of fashion now, I think, but I bought a 16 oz can of Army Surplus Mil-Spec talcum powder at one on Division St., N. side of Spokane, for $1, in 1961. No perfume...the VC would smell it from a mile away. How's that for memory? Can't remember what I had for dinner last night, but I know I'm getting the same stuff again tonight! LL~ Steve
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I have done both corn starch and talc(could only find scented) and if too much in the dope plus dope is too thick I had problems. I use enough talc to give the dope(50% dope and thinner) to make it almost like milk. I brush on a coat, wait a day and brush on another coat. Let set for a couple of days and then sand.
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Thank you for the help. I will hopefully try to cover the wings this weekend. I will then be able to try out this method.
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Buzz Wilson has a ton of the talc suggested by PT Granderson in his finish article. Contact Buzz and maybe he'll sell some.....think it's from an industrial size purchase.
You can find Buzz on Flyinglines under combat articles