I had an interesting experience after prepping the Pinewood Derby cars for their 3rd coat of sanding sealer. After sanding, I used denatured alcohol (BORG purchase) to clean the dust and to prep the surface. After a wipe or two if felt sticky, like it was dissolving the sealer. I stopped and re-sanded the surface and all seamed good. I then found some home 91% isopropyl alcohol and cut it with tap water by two-thirds. That seemed to work with no detectable deleterious effects.

The denatured alcohol said that it contained methanol. Anyway, lesson learned. Not all alcohols behave the same way.

Greg

I actually prefer Jack Daniels, but I wouldn't waste it by wiping it on anything.

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Denatured is serious stuff. It definitely has its uses, but I keep it away from things whose finish I don't want to mess up.

Isopropyl, I use for all sorts of cleaning applications. In fact, I used it yesterday to clean the "sticker gunk" from the cover of a paperback book. (I bought it on sale, and wanted the evidence removed before I wrapped it up as a gift!)

Denatured alcohol (called "methylated spirits" in the UK) is ethyl alcohol (the drinkin' kind) that contains 10% methyl alcohol (wood alcohol) to make it both poisonous to drink and to exempt it from liquor taxes. It's often used as a fuel in alcohol burners, chafing dishes, and outdoor cookstoves. When I worked at the Miami Space Transit Planetarium in Miami, we used denatured alcohol to clean the heads on the Tascam and Sony reel-to-reel tape player/recorders.

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This post made my day! I thought I was the only one who did that. I'm giving a prevously veiwed copy of a video series this year.

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OK - Chemistry Nerd Alert! Skip if you have no interest in chemistry and hard science. You have been warned!

Methyl Alcohol is an alcohol with only one carbon atom (CH3OH). The oxygen-hydrogen coupling at the end is what makes it an alcohol. Methyl alcohol is also referred to as methanol or Wood Alcohol.

Ethyl Alcohol has two carbons (CH3CH2OH). Also called ethanol or pure grain alcohol. As Blackshire noted, denatured alcohol has a bit of methanol added to make it unfit for drinking. We use denatured ethanol quite a bit in the lab.

Propyl alcohol (or propanol or rubbing alcohol) has three carbons. There are two kinds - normal propyl alcohol, where the OH is on the end carbon, and isopropyl, where the OH is attached to the center carbon. Rubbing alcohol often has a couple other things added (such as oils) to make it "slicker" when rubbing on the body. This could account for the lower "stickiness" factor. Not sure why the denatured made it sticky unless you had some sanding sealer on there and the alcohol was attacking that.

Greg

The only butyrate dopes I know of that are attacked by Methyl or Denatured Ethyl alcohol are the various brands of "Sanding Sealer" marketed under the Pactra Aero Gloss, Sig, and Brodak labels.
Although those sanding sealers are labeled FALSELY as "Fuel Proof" (Glow fuel is predominantly Methanol), they are not unless top-coated by Clear or Color Dope.
Nitrate dope is not fuel (Methanol) proof either and must be topcoated.
All other butyrate dopes, be it Balsa Fillercoat, Clear, and all colors are Methanol, Ethanol, and Nitromethane-proof (up to 40% in the mix).
Obviously most Aromatic (Benzene ring derivatives) Solvents and Ketones (Acetone, MEK, MIBK, etc) will attack Butyrate products.
Alcohols with a 3-carbon chain (Isopropyl or N-propyl) or longer (butanol, amyl alcohol, etc.) typically will not attack any butyrate dope including Sanding Sealer.
As you found, if you want to "clean" the surface of a substrate prepped with Sanding Sealer, Isopropyl is okay. If you do this, it would be BEST to use automotive Iso-dry Isopropyl dry-gas as it contains NONE of the mild lubricants found in some brands of "rubbing" alcohol.

By the way, Chlorinated Hydrocarbons such as Methylene Chloride, Perchloroethylene and 1,1,1 Trichloroethylene will VIGOROUSLY attack and dissolve Butyrate Dopes at will. Dont even think about using "Brakleen" as a "cleaner for a dope surface.

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Thanks Greg and GH for the information. I do appreciate anyone who takes the time to impart knowledge.

I am a lot more interested in chemistry and physics since I came back to rocketry. I can see why in "The Rocket Boys" the Coalwood boys were so bent on expanding their knowledge of science so that they could engineer their own rockets. Application of knowledge is a good thing.

Greg

Well, the minor in Chemistry does come in handy once in a while! I was actually one of the weird ones in College who actually enjoyed Organic Chem.!

Greg

I had to explain this to some high school students on Thursday not to drink the alcohol in the lab bottle.