I’m trying to make an edible hydrophobic coating for a tart shell. If anyone knows of a way to lower the viscosity of an edible wax enough to make it sprayable I’d really appreciate it.

I have a paper here that explains that it could be done but it doesn’t state the solvent used


  • 2
    $\begingroup$ Because of the specific tag baking and tart, I speculate sibling seasoned advice may provide an audience with more (practical) expertise here. $\endgroup$
    – Buttonwood
    Jan 12, 2023 at 9:50
  • $\begingroup$ Also, since random organic solvents might not be food-safe, this question should not be here due to possible health concerns. That said, if you do succeed in waterproofing that tart, you might snack on it submerged: youtube.com/watch?v=5UILp88D3XQ $\endgroup$ Jan 12, 2023 at 21:17

2 Answers 2


In Section 2.2 of the paper cited, the method and solvent are specified: "...soybean wax suspension was prepared through mixture of 1 g of soybean wax and 50 mL ethanol solution followed by heating at 65º C for 3 min." The superhydrophobic character of the coating described in the paper may not be necessary for the tart shell (see below for examples). Extra care must be observed when following this recipe, for the flash point of ethanol is only 14º C, but this method has the advantage of easy evaporation and safe consumption of the carrier solvent.

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Edible waxes can be emulsified and dispersed in water and are widely used to coat fruit and vegetables. Spraying an aqueous solution onto a tart shell could be adjusted so as not to overwet the shell, but some experimentation will be necessary. Wax emulsions are commercially available from many sources, such as Hexion (Ref 1) and Lubrizol (Ref 2). More commercial sources are listed in Ref 3.

Or, with a bit of experimentation, a food-grade wax (e.g., carnauba or polyethylene) and a food-grade emulsifier can be emulsified with intense stirring in hot water (to melt the wax), then cooled to stabilize the formulation.

Cooking and baking are specialized branches of chemistry, but you can eat your mistakes.

Ref 1. https://www.hexion.com/en-US/chemistry/wax-emulsions

Ref 2. https://www.lubrizol.com/-/media/Lubrizol/Coatings/Coatings-Literature/Wax-Additives-Product-Guide---22-122162.pdf

Ref 3. https://www.thomasnet.com/products/fruit-vegetable-coating-wax-93060200-1.html


I never tried rubbing carnauba wax on a tart and brushing it to a glossy shine, but one other idea came to mind: food grade ethyl acetate.

Carnuba wax could be dissolved in ethyl acetate and sprayed on, with a few more minutes in the oven at elevated temperature to evaporate the solvent.

Ethyl acetate is approved for use in foods as a flavor additive and should be safe in low concentrations.

Carnuba wax could also be softened with heat and applied to tarts in a rotating tumbler. This is how it is added to the surface of candies to make them shine.

It should be cautioned that adding excessive amounts of wax may affect the palate feel and texture of the tart. Finding a waterproof wrapping may be better. However, if feeling a bit adventurous, one might consider a chocolate coating as well.

  • $\begingroup$ Wouldn't a tart fall apart if tumbled? $\endgroup$
    – Buck Thorn
    Jan 13, 2023 at 8:16
  • $\begingroup$ Hmm, I assume the approve as flavour additive is not supposed to be extended for bigger amounts, used for spraying. As there are no harmful nor harmless chemicals. Their amounts are. $\endgroup$
    – Poutnik
    Jan 13, 2023 at 9:54
  • $\begingroup$ @Poutnik surprisingly, ethyl acetate (ester of ethanol and acetic acid) has an LD 50 comparable to neat alcohol. (One might get drunk and have a hangover at the same time). Other waxes could be tried. Cocoa butter had me curious. $\endgroup$ Jan 13, 2023 at 10:14
  • $\begingroup$ It does not contradict what I have said. Food acceptance involves also long term influence, not covered by LD parameters. I do not have handy conditions of its usage, but I doubt it would be unconditional. $\endgroup$
    – Poutnik
    Jan 13, 2023 at 10:18
  • $\begingroup$ @Poutnik Aye, and we're the right track with waxes and solvents. $\endgroup$ Jan 13, 2023 at 10:27

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