Paul: I have on more than one occasion, commented on a finish, and even concrete, drying when the reisdent expert utters "Don't you mean cure, Peter?" In my line of work I am quite used to the idea that there is often no cure, but I digress.
I recently had a draining experience when caulking a shower. I had some caulking, that dries, no it says "usually cures within 24 hours." It is GE Silicone II caulking. Great news! I have some caulking left over from before and it hasn't dried up in the tube. What a stroke of good luck.
I caulk the seam and wait for it to cure. Monday, Tuesday, Wednesday ... Trust me, there are few things as sticky as uncured silicone caulking. The cleanup was unpleasant. So I buy a new tube, instant success within 24 hours.
I would be grateful if you could talk about curing and drying as it relates to finishes. In my case, drying was not the cure.
Finding The Right Cure
Moderator: jingle_jangle
Finding The Right Cure
Life, as with music, often requires one to let go of the melody and listen to the rhythm
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jingle_jangle
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A pet topic of mine, Peter.
I began early on in my finishing days, to make every attempt to distinguish in my mind and conversation, between these two processes. (I know you are wondering: "conversation? What does this guy talk about?)
This is also a major issue in my classes. When I produced the demonstration videos for my online classes, I expended a good deal of effort in emphasizing the distinction between "curing" and "drying" as it relates to materials and finishes. There's not a day goes by when I don't have a student use the term "dry" when he or she means "cure". And I'm quick to correct, because understanding this difference is important in aligning our thinking to the processes involved so that we can plan time and use appropriate materials.
In the broadest terms, "drying" refers to the hardening of a material due to reaction with air or the atmosphere, whereas "curing" refers to a reaction between a material and a chemical additive (termed a "catalyst") which, when mixed with the material, causes it to harden chemically, even in the absence of air.
(Strictly speaking, "drying" is a chemical reaction, too, usually with oxygen as the catalyst, but let's not confuse things. If it uses air, it dries, and if it uses a catalyst, it cures.)
It helps also to know that drying takes place from the surface of a material into its depth, and curing takes place throughout the thickness of a material simultaneously. Sometimes both happen simultaneously (as in the case of tub caulking), sometimes they happen in series (most epoxy, urethane, and polyester paints first "dry" or "flash off" through the evaporation of their solvent content, and then "cure" as the complex molecules of their chemistry crosslink to form a hard, impervious skin.)
Concrete and plaster cure through a process called "hydration", which is a chemical process taking place between the water and the cement, which is the reactive component of concrete, the other components being stone or aggregate, and sand or silica.
As it relates to finishes, nitrocellulose and acrylic lacquers both air dry and polyesters, epoxies, and urethanes all cure, although curing finishes all contain solvents which reduce their viscosity to sprayable or brushable consistency, and these solvents evaporate, or flash-off before curing commences.
In the case of most larger electric guitar manufacturers these days, the color coats are made up of substances which dry, whereas the glossy clearcoat is made up of substances that cure. This includes RIC's conversion varnish.
Peter, your problem with the tub caulking is strange. Tub caulking actually "cures" by reaction with the moisture in the air. As long as it remains liquid (in the tube), it remains reactive, and once squeezed out of the tube, it usually catalyzes within 24 hours. You must have had a bad batch, or too much moisture in the air or on the surface you were trying to caulk.
So now, pay attention to the resident expert, and when he says "cures" when he means "dries", you can correct him.
And, believe it or not, there is much, much more to this topic of drying versus curing, but those are the basics.
I began early on in my finishing days, to make every attempt to distinguish in my mind and conversation, between these two processes. (I know you are wondering: "conversation? What does this guy talk about?)
This is also a major issue in my classes. When I produced the demonstration videos for my online classes, I expended a good deal of effort in emphasizing the distinction between "curing" and "drying" as it relates to materials and finishes. There's not a day goes by when I don't have a student use the term "dry" when he or she means "cure". And I'm quick to correct, because understanding this difference is important in aligning our thinking to the processes involved so that we can plan time and use appropriate materials.
In the broadest terms, "drying" refers to the hardening of a material due to reaction with air or the atmosphere, whereas "curing" refers to a reaction between a material and a chemical additive (termed a "catalyst") which, when mixed with the material, causes it to harden chemically, even in the absence of air.
(Strictly speaking, "drying" is a chemical reaction, too, usually with oxygen as the catalyst, but let's not confuse things. If it uses air, it dries, and if it uses a catalyst, it cures.)
It helps also to know that drying takes place from the surface of a material into its depth, and curing takes place throughout the thickness of a material simultaneously. Sometimes both happen simultaneously (as in the case of tub caulking), sometimes they happen in series (most epoxy, urethane, and polyester paints first "dry" or "flash off" through the evaporation of their solvent content, and then "cure" as the complex molecules of their chemistry crosslink to form a hard, impervious skin.)
Concrete and plaster cure through a process called "hydration", which is a chemical process taking place between the water and the cement, which is the reactive component of concrete, the other components being stone or aggregate, and sand or silica.
As it relates to finishes, nitrocellulose and acrylic lacquers both air dry and polyesters, epoxies, and urethanes all cure, although curing finishes all contain solvents which reduce their viscosity to sprayable or brushable consistency, and these solvents evaporate, or flash-off before curing commences.
In the case of most larger electric guitar manufacturers these days, the color coats are made up of substances which dry, whereas the glossy clearcoat is made up of substances that cure. This includes RIC's conversion varnish.
Peter, your problem with the tub caulking is strange. Tub caulking actually "cures" by reaction with the moisture in the air. As long as it remains liquid (in the tube), it remains reactive, and once squeezed out of the tube, it usually catalyzes within 24 hours. You must have had a bad batch, or too much moisture in the air or on the surface you were trying to caulk.
So now, pay attention to the resident expert, and when he says "cures" when he means "dries", you can correct him.
And, believe it or not, there is much, much more to this topic of drying versus curing, but those are the basics.
“I say in speeches that a plausible mission of artists is to make people appreciate being alive at least a little bit. I am then asked if I know of any artists who pulled that off. I reply, 'The Beatles did.”
― Kurt Vonnegut
― Kurt Vonnegut
And I thought this thread was about the band "The Cure".
Peter, no good to you now, but your caulk would have cured pronto if you had poured vinegar on it. Acetic acid in combination with oxygen kicks the stuff off. For a little extra flavor and color, I suppose you could have used balsamic vinegar!
Peter, no good to you now, but your caulk would have cured pronto if you had poured vinegar on it. Acetic acid in combination with oxygen kicks the stuff off. For a little extra flavor and color, I suppose you could have used balsamic vinegar!
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jingle_jangle
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That's right--if you smell the stuff, it smells like vinegar--that should be a good clue for good glue...
“I say in speeches that a plausible mission of artists is to make people appreciate being alive at least a little bit. I am then asked if I know of any artists who pulled that off. I reply, 'The Beatles did.”
― Kurt Vonnegut
― Kurt Vonnegut