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My oil varnish is mesmerizing for small bees, insects, etc...


MANFIO

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Does not help you, but I remember painting a garage door with white color and swarms of tiny flies sitting on it and getting stuck. 

God, I hated them. I was young and wanted to impress my girlfriends parents by painting while they were gone and those flys kept fckng it up...

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Just now, iNeedAnswers said:

Does not help you, but I remember painting a garage door with white color and swarms of tiny flies sitting on it and getting stuck. 

God, I hated them. I was young and wanted to impress my girlfriends parents by painting while they were gone and those flys kept fckng it up...

Ha!!!  Funny!

 

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My first thought is that they're attracted to UV - certainly it's used to make whites appear whiter - although there could be other things about varnish that they like.  Maybe we're (it happens to me as well) just sampling the insect flux through a violin-sized volume of space over the time that the varnish is soft enough to catch them.

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1 hour ago, Dr. Mark said:

 Maybe we're (it happens to me as well) just sampling the insect flux through a violin-sized volume of space over the time that the varnish is soft enough to catch them.

The amber principle. Entomologists mix up a concoction  called 'tanglefoot'  which is a soft uncooked varnish to sample insect populations. It doesn't usually include specific attractants however linoleic acid is a strong attractant for some types because it is emitted by dead or dying insects. It is the insect death smell. I used to brush a bit of raw linseed inside a roll of newspaper to catch and remove earwigs from my vegetable patch. 

 

 

Edit: tanglefoot usually has resin and a proportion of castor oil in it but is only heated to combine tge ingredients. Castor oil contains some linoleic and oleic acids but is mostly ricinoleic acid, a C18 W9 hydroxy fat which is interesting in that is used as a toughener cooked into in urethane varnishes.

Has anyone tried adding small amounts of it to cooked oil varnishes?

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1 hour ago, LCF said:

Has anyone tried adding small amounts of it to cooked oil varnishes?

It has been used as a softener or plasticizer in spirit varnishes, since it is miscible with alcohol.
It eventually polymerizes though, so not a good long-term solution.

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29 minutes ago, David Burgess said:

It has been used as a softener or plasticizer in spirit varnishes, since it is miscible with alcohol.
It eventually polymerizes though, so not a good long-term solution.

Interesting to hear that. It would be a good characteristic in a cooked varnish.  

Wikipedia: "Among fatty acids, ricinoleic acid is unusual in that it has a hydroxyl functional group on the 12th carbon atom. This functional group causes ricinoleic acid (and castor oil) to be more polar than most fats. The chemical reactivity of the alcohol group also allows chemical derivatization that is not possible with most other seed oils."

 

Unknown source:

" The average functionality of castor oil is 2.7, so it is widely used as rigid polyol of polyurethane industry."

 

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49 minutes ago, David Burgess said:

It has been used as a softener or plasticizer in spirit varnishes, since it is miscible with alcohol.
It eventually polymerizes though, so not a good long-term solution.

Do you have MagnaPlas there? It's a white paste you put under a bandaid and leave for a while to get splinters out. It's made from magnesium sulphate plus castor oil. After a year or two in the pot it sets as hard as plaster.

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On 5/13/2024 at 8:19 AM, David Burgess said:

It has been used as a softener or plasticizer in spirit varnishes, since it is miscible with alcohol.
It eventually polymerizes though, so not a good long-term solution.

@David Burgess What effect does it have when it polymerizes? Does the finish get brittle?

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7 hours ago, LCF said:

@David Burgess What effect does it have when it polymerizes? Does the finish get brittle?

Yes, the finish becomes more brittle as the castor oil gradually converts to a gum or resin, somewhat like drying oils do, but much more slowly. I shouldn't have specified that this is due to polymerization though since I really don't know if this change is due to polymerization, oxidation, or some combination of the two.

It was once the preferred lubricant for high-performance engines, but has largely been replaced by synthetic oils, partly because the newer synthetics have better long-term stability, leaving fewer gummy/resinous deposits.

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1 hour ago, David Burgess said:

Yes, the finish becomes more brittle as the castor oil gradually converts to a gum or resin, somewhat like drying oils do, but much more slowly. I shouldn't have specified that this is due to polymerization though since I really don't know if this change is due to polymerization, oxidation, or some combination of the two.

It was once the preferred lubricant for high-performance engines, but has largely been replaced by synthetic oils, partly because the newer synthetics have better long-term stability, leaving fewer gummy/resinous deposits.

Since it is a C18 monounsaturate you might expect it to 'dry' eventually. One of the many Italian varnish research papers found oxidised oleic acid in the mix (also C18 mono)  in their analysis so even that goes off. The hydroxy group and the subsequent polarity of castor oil make it more interesting though and probably more able to form polymers.

I have a hunch that it might cook up with sandarach. 

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  • 3 weeks later...
On 5/15/2024 at 7:35 PM, LCF said:

I have a hunch that it might cook up with sandarach. 

I tried it and it does. I cooked a minibatch of 4g of sandarach and 6g castor oil at 200'C for an hour and it blended perfectly into something like sticky toffee.  Now I'll split it in two, mix one half to a brushing consistency with alcohol and see if it dries. (Or maybe a slower evaporating polar solvent?) The other half will be cooked up with some linseed oil to see if it combines and makes a useful oil varnish. 

Otherwise I've just made some good flypaper primer!

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On 5/30/2024 at 10:47 AM, LCF said:

I tried it and it does. I cooked a minibatch of 4g of sandarach and 6g castor oil at 200'C for an hour and it blended perfectly into something like sticky toffee.  Now I'll split it in two, mix one half to a brushing consistency with alcohol and see if it dries. (Or maybe a slower evaporating polar solvent?) The other half will be cooked up with some linseed oil to see if it combines and makes a useful oil varnish. 

Otherwise I've just made some good flypaper primer!

Hi LCF,

I hope this will not discourage you, but your varnish is unlikely to dry in any reasonable time frame. Castor oil in its raw state is not considered a drying oil. It is converted into one by dehydrating it. This is usually an industrial process involving catalysts (e.g. sulfuric acid). In this form, it was used as a cheaper alternative to tung oil, and I believe it still is. Tung became unavailable when WWII started, and that led to much research on using soy, castor, etc. Tung never recovered commercially after that. 

I have come across a couple references to dehydrating castor oil in a kettle, simply by cooking at ca. 280 C for "a few hours". I *think* the problems associated with this approach are (1) darkening, which is no problem for a fiddle maker; and (2) polymerization, making it difficult to store and ship. If I were to experiment, I'd try dehydrating it in the kettle and then immediately combining it with resin. I should give it a whirl! Please let us know how your experiments turn out.

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12 minutes ago, Steve Voigt said:

Hi LCF,

I hope this will not discourage you, but your varnish is unlikely to dry in any reasonable time frame. Castor oil in its raw state is not considered a drying oil. It is converted into one by dehydrating it. This is usually an industrial process involving catalysts (e.g. sulfuric acid). In this form, it was used as a cheaper alternative to tung oil, and I believe it still is. Tung became unavailable when WWII started, and that led to much research on using soy, castor, etc. Tung never recovered commercially after that. 

I have come across a couple references to dehydrating castor oil in a kettle, simply by cooking at ca. 280 C for "a few hours". I *think* the problems associated with this approach are (1) darkening, which is no problem for a fiddle maker; and (2) polymerization, making it difficult to store and ship. If I were to experiment, I'd try dehydrating it in the kettle and then immediately combining it with resin. I should give it a whirl! Please let us know how your experiments turn out.

Thanks very much for that info and it is something I will further experiment with.

 

I don't expect the C.O.  to dry but I had to find out after David mentioned it as a possible problem with it in shellac mixtures. The main interest for me was that sandarach combines with it while it doesn't easily do that lso and sandarach (callitrus) resin is an abundant local wild resin.  It's not really a surprise that happens given that both are ingredients together with shellac and mastic in many spirit varnish recipes.  I'm interested to see if C.O. can be a go-between solvent due to (the ricinoleic) being polar from the location of the hydroxyl group but also a C18 monounsaturate  containing oleic and linoleic acids thus compatible with those.  It's like a thick surfactant in some ways. Perhaps cooking it at high oil varnish temperatures with some lso  will be enough to stir it up a little. 

Castor oil is in high demand as a feedstock now and getting more expensive so it wouldn't be worth converting to a tung-like oil  for the economics.

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  • The reason why insects are attracted to light has been recently discovered, long explanation, but it has to do with them becoming directionally challenged and confusing the light with the sun, them thinking they are flying straight when really they are circling around, my theory is that the bugs mistake reflective glare spots for lights and start to circle the instrument and eventually hit and then stick to it.
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