What's in the finish?

[colin]

(in another thread)
Also, I think pretty much everybody will agree that the finish is way better and more consistent than before.

This reminds me, Morrow and I were chatting recently about the finish and the warm-to-room-temperature-before-opening-the-box warning that comes with a new Rick. Does anyone here know what kind of finish Rickenbacker uses?

I was going to take a couple of chips from under the TRC into the lab and figure it out, but maybe asking here would be easier.

[Grey]

New Ricks have a UV-cured Poly finish. Older Ricks used Conversion Varnish and I believe Nitrocellulose was used for a brief period in the late 1950's.

[cjj]

The conversion varnish was a 2 part catalyzing polyurethane. The UV cured is a polyester, I believe...

[BAD RONBO, KiLLeR DWaRfS]

i have a bass that my wonderous road crew finish ruined due to us playing a show in winterpeg, manitoba in the early '90's. at gear load in it was -40 degrees wind chill (this is a place where the parking lots have places for you to plug in your block heater to keep the oil warm !!!), and opened the case and put the bass on a stand near the stage...creeaaakkkkkk ! the black laquer looks like the mirrors bruce lee smashed in enter the dragon !

[cjj]

Oh yeah. I remember that sort of weather when I lived in Malta, MT. But we didn't have the luxury of places to plug in vehicles, you just left 'em running...

[jingle_jangle]

Maybe block heaters should be a Rick option...

[nukebass]

I don't think it is about what's in the finish, but the different expansion rates of the wood and the finish. If the bass and finish are cold and the wood suddenly begins to warm up to room temperature, it expands faster than the finish (I think that's right). At some point, if the temperature gradient is large enough, the wood will expand to the point of damaging the finish because the finish can't "get out of the way" of the wood. This is similar to water freezing in and breaking pipes, but in the other direction (because water expands when cooling below 39F).

[colin]

I don't think it is about what's in the finish, but the different expansion rates of the wood and the finish. If the bass and finish are cold and the wood suddenly begins to warm up to room temperature, it expands faster than the finish (I think that's right). At some point, if the temperature gradient is large enough, the wood will expand to the point of damaging the finish because the finish can't "get out of the way" of the wood. This is similar to water freezing in and breaking pipes, but in the other direction (because water expands when cooling below 39F).

Probably the other way around, the finish expands before the wood upon warming because it's in contact with the warmer air, presenting a thermal gradient. The thermal gradient won't be as severe for a cold instrument left inside its (cold) case. As for expansion, it could even be the outer side of the finish expands before the inner side since this could lead to some internal stresses within the coating. In either case, some polymers can withstand stresses better than others. It depends how brittle the material is, so it really is about what's in the finish, to some extent anyway.

[grygrx]

i have a bass that my wonderous road crew finish ruined due to us playing a show in winterpeg, manitoba in the early '90's. at gear load in it was -40 degrees wind chill (this is a place where the parking lots have places for you to plug in your block heater to keep the oil warm !!!), and opened the case and put the bass on a stand near the stage...creeaaakkkkkk ! the black laquer looks like the mirrors bruce lee smashed in enter the dragon !

Pics?

[jingle_jangle]

I don't think it is about what's in the finish, but the different expansion rates of the wood and the finish. If the bass and finish are cold and the wood suddenly begins to warm up to room temperature, it expands faster than the finish (I think that's right). At some point, if the temperature gradient is large enough, the wood will expand to the point of damaging the finish because the finish can't "get out of the way" of the wood. This is similar to water freezing in and breaking pipes, but in the other direction (because water expands when cooling below 39F).

Probably the other way around, the finish expands before the wood upon warming because it's in contact with the warmer air, presenting a thermal gradient. The thermal gradient won't be as severe for a cold instrument left inside its (cold) case. As for expansion, it could even be the outer side of the finish expands before the inner side since this could lead to some internal stresses within the coating. In either case, some polymers can withstand stresses better than others. It depends how brittle the material is, so it really is about what's in the finish, to some extent anyway.

It works both ways. Any substrate with a noticeably higher or lower rate of thermal expansion and contraction that the coating, will stress the coating as it goes through its thermal cycling. (The relicking fools experts will leave a body or neck in the sun and then hit the surface with carbon dioxide or canned air.) This is the opposite of the typical situation that Rick owners fear.

It comes down to the dried or cured film strength of the coating across its surface. This is a product of the material itself and its applied thickness. Thin nitrocellulose that is aged is very fragile. Furniture finishes like alkyd varnishes also get brittle with age. So-called "conversion" varnishes are typically rated for interior use. RIC used to use the same CV that wooden coffin makers favored, as it was higher-rated for weather resistance and resistance to checking. However, there are exterior clearcoats that are far superior to any furniture or interior CVs, while also offering non-yellowing features.

These are catalyzing urethane, automotive clearcoats. They have two drawbacks: cost and durability. These finishes cost approximately 4X the price per gallon of furniture CVs. They are so durable that they require more aggressive abrasives to flatten and buff, and must be levelled and buffed using a strict schedule tied to rate of cure. Wait too long, and it seems that you're buffing granite. Imagine the thermal cycle of the finish on a dark-colored car after a few hours in hot sun. The finish temperature can exceed 100 degrees centigrade, yet it remains relatively stable.

I use these automotive clearcoats except when a customer specifies nitrocellulose by name. I have not seen any sort of failure of the clearcoat film in hundreds of refinishes that I've done since 2005. Frankly, they are worth the extra work involved in getting them glassy.

Two more points. First, the previous paragraphs sum up exactly why I remain unconvinced as to the suitability or waterborne clearcoats for guitar finishing, at least at the present time. My manufacturers rep does sell several waterborne clearcoats that are exterior-rated--for five years only. They steer me away from them whenever I inquire, telling me that more R&D is needed still.

Second, RIC's new UV-cured polyester has a number of advantages, but germane to this discussion is its film strength, which is tied to specific additives in the polyester itself, but also to film thickness, which I have not measured in this case, but which in my experience is somewhat greater than the older CVs. In any event, this stuff, according to the tech sheets, looks to be generally bulletproof and much more resistant to thermal shock than anything they've used before. Although acclimatization is still a recommended practice, I can see far fewer cases of thermal checking in the future.

[colin]

Very interesting! Thanks Paul! BTW, do you have a link to the tech sheeets for these coatings? I'm curious.

[BAD RONBO, KiLLeR DWaRfS]

i have a bass that my wonderous road crew finish ruined due to us playing a show in winterpeg, manitoba in the early '90's. at gear load in it was -40 degrees wind chill (this is a place where the parking lots have places for you to plug in your block heater to keep the oil warm !!!), and opened the case and put the bass on a stand near the stage...creeaaakkkkkk ! the black laquer looks like the mirrors bruce lee smashed in enter the dragon !

Pics?

would be tough to see in a pic unless i use the reflecting light to show it. i think i showed it to boyer when he came to my "fortress of solitude" .

[jingle_jangle]

Very interesting! Thanks Paul! BTW, do you have a link to the tech sheeets for these coatings? I'm curious.

I'm on my iPad right now, so I don't have access to those bookmarks. However, Google is your friend.

Try keywords "UV cured polyester".

[rickyfricky]

Follow-up question:

So what would make some Blueboys go greenish (my 4004cii included), and some not?

[s4001]

Maybe block heaters should be a Rick option...