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Scott Rosen
07-21-2003, 11:01 AM
Since the first time I used CPES under varnish, I've had a suspicion that it didn't look the same as plain varnish.

Last year (or maybe it was the year before), I wooded all of my outside brightwork, all teak. I CPESed and varnished the port toe rail and pilothouse, then followed with lots of coats of varnish. I ran out of time before I got to the starbord rail.

It looked good. But it looked different. It seemed to me that the epoxy used as the sealer coat has different optical qualities than a traditional tung oil/phenolic resin varnish. The CPES evened out the color, but softened the fiery glow and three-dimensional effect that I get when I seal the wood with varnish. Plain varnish on teak seems to catch the light source in a dramatic way and makes the wood come alive. CPES acts more like a stain in that it evens the color, but seems to react less dramatically to the light.

I finally finished the starboard rail, and I decided to skip the CPES. My suspicions were confirmed. I like the look of varnished teak without CPES better.

Over the winter, I conducted a simple experiment. I took three premium varnishes, Epifanes, Detco and Rivale and used them, in sections, on a piece of teak lumber. On one side, I sealed with CPES. On the other side I sealed with the varnish. What I found was that on the CPESed side, all three varnishes looked the same--only slight differences in color. On the non-CPESed side, each varnish looked markedly different from the other and seemed to have its own personality.

What I concluded was that the differences in varnish appearance are mostly caused by the optics of the sealer coats in the woodgrain, not by the color or hue of the build and topcoats.

When you use CPES under varnish, it is the CPES that primarily determines the appearance, not the varnish.

Of course, some of you may prefer the look of CPESed wood, just as some folks prefer stained mohogany over unstained.

Anyone else notice this?

Scott Rosen
07-21-2003, 11:01 AM
Since the first time I used CPES under varnish, I've had a suspicion that it didn't look the same as plain varnish.

Last year (or maybe it was the year before), I wooded all of my outside brightwork, all teak. I CPESed and varnished the port toe rail and pilothouse, then followed with lots of coats of varnish. I ran out of time before I got to the starbord rail.

It looked good. But it looked different. It seemed to me that the epoxy used as the sealer coat has different optical qualities than a traditional tung oil/phenolic resin varnish. The CPES evened out the color, but softened the fiery glow and three-dimensional effect that I get when I seal the wood with varnish. Plain varnish on teak seems to catch the light source in a dramatic way and makes the wood come alive. CPES acts more like a stain in that it evens the color, but seems to react less dramatically to the light.

I finally finished the starboard rail, and I decided to skip the CPES. My suspicions were confirmed. I like the look of varnished teak without CPES better.

Over the winter, I conducted a simple experiment. I took three premium varnishes, Epifanes, Detco and Rivale and used them, in sections, on a piece of teak lumber. On one side, I sealed with CPES. On the other side I sealed with the varnish. What I found was that on the CPESed side, all three varnishes looked the same--only slight differences in color. On the non-CPESed side, each varnish looked markedly different from the other and seemed to have its own personality.

What I concluded was that the differences in varnish appearance are mostly caused by the optics of the sealer coats in the woodgrain, not by the color or hue of the build and topcoats.

When you use CPES under varnish, it is the CPES that primarily determines the appearance, not the varnish.

Of course, some of you may prefer the look of CPESed wood, just as some folks prefer stained mohogany over unstained.

Anyone else notice this?

Scott Rosen
07-21-2003, 11:01 AM
Since the first time I used CPES under varnish, I've had a suspicion that it didn't look the same as plain varnish.

Last year (or maybe it was the year before), I wooded all of my outside brightwork, all teak. I CPESed and varnished the port toe rail and pilothouse, then followed with lots of coats of varnish. I ran out of time before I got to the starbord rail.

It looked good. But it looked different. It seemed to me that the epoxy used as the sealer coat has different optical qualities than a traditional tung oil/phenolic resin varnish. The CPES evened out the color, but softened the fiery glow and three-dimensional effect that I get when I seal the wood with varnish. Plain varnish on teak seems to catch the light source in a dramatic way and makes the wood come alive. CPES acts more like a stain in that it evens the color, but seems to react less dramatically to the light.

I finally finished the starboard rail, and I decided to skip the CPES. My suspicions were confirmed. I like the look of varnished teak without CPES better.

Over the winter, I conducted a simple experiment. I took three premium varnishes, Epifanes, Detco and Rivale and used them, in sections, on a piece of teak lumber. On one side, I sealed with CPES. On the other side I sealed with the varnish. What I found was that on the CPESed side, all three varnishes looked the same--only slight differences in color. On the non-CPESed side, each varnish looked markedly different from the other and seemed to have its own personality.

What I concluded was that the differences in varnish appearance are mostly caused by the optics of the sealer coats in the woodgrain, not by the color or hue of the build and topcoats.

When you use CPES under varnish, it is the CPES that primarily determines the appearance, not the varnish.

Of course, some of you may prefer the look of CPESed wood, just as some folks prefer stained mohogany over unstained.

Anyone else notice this?

NormMessinger
07-21-2003, 11:34 AM
Verrrry Interesting! Now to put that piece of teak out in the weather and see what happens. How does one do an accelerated weathering test?

NormMessinger
07-21-2003, 11:34 AM
Verrrry Interesting! Now to put that piece of teak out in the weather and see what happens. How does one do an accelerated weathering test?

NormMessinger
07-21-2003, 11:34 AM
Verrrry Interesting! Now to put that piece of teak out in the weather and see what happens. How does one do an accelerated weathering test?

W Hersey
07-21-2003, 11:38 AM
Scott,

Yep. I did a similar experiment last year with sme of my neighbor's CPES (wasn't going to buy it for an experiment). A piece of teak that was going to be used for a cabinet was sealed with CPES on one side, then three coats of Flagship. The other side was one 50/50 thinned Flagship, then three coats.

It was left outdoors, in the dink to be exact, with equal sun and weather exposure.

The CPES side, right from the start, had little "life" or luster, and the grain seemed muted. The other side was fine.

Both weathered equally, and both needed another coat at the same time. Both held tenaciously to the teak, so that was not an issue. We used the CPES side as the INSIDE of the cabinmet door. I'm sure it is a great product for certain uses, but under exterior varnish on teak, the jury is out. I'm not convinced.

Bill

W Hersey
07-21-2003, 11:38 AM
Scott,

Yep. I did a similar experiment last year with sme of my neighbor's CPES (wasn't going to buy it for an experiment). A piece of teak that was going to be used for a cabinet was sealed with CPES on one side, then three coats of Flagship. The other side was one 50/50 thinned Flagship, then three coats.

It was left outdoors, in the dink to be exact, with equal sun and weather exposure.

The CPES side, right from the start, had little "life" or luster, and the grain seemed muted. The other side was fine.

Both weathered equally, and both needed another coat at the same time. Both held tenaciously to the teak, so that was not an issue. We used the CPES side as the INSIDE of the cabinmet door. I'm sure it is a great product for certain uses, but under exterior varnish on teak, the jury is out. I'm not convinced.

Bill

W Hersey
07-21-2003, 11:38 AM
Scott,

Yep. I did a similar experiment last year with sme of my neighbor's CPES (wasn't going to buy it for an experiment). A piece of teak that was going to be used for a cabinet was sealed with CPES on one side, then three coats of Flagship. The other side was one 50/50 thinned Flagship, then three coats.

It was left outdoors, in the dink to be exact, with equal sun and weather exposure.

The CPES side, right from the start, had little "life" or luster, and the grain seemed muted. The other side was fine.

Both weathered equally, and both needed another coat at the same time. Both held tenaciously to the teak, so that was not an issue. We used the CPES side as the INSIDE of the cabinmet door. I'm sure it is a great product for certain uses, but under exterior varnish on teak, the jury is out. I'm not convinced.

Bill

John E Hardiman
07-21-2003, 11:42 AM
Originally posted by NormMessinger:
How does one do an accelerated weathering test?There is an ASTM standard, hundreds actually, depending on the coating and the substrate. Go to www.astm.org (http://www.astm.org) and do a search. Basically, for a marine environment, it is a heated box with bright lights and a saltwater wash system.

John E Hardiman
07-21-2003, 11:42 AM
Originally posted by NormMessinger:
How does one do an accelerated weathering test?There is an ASTM standard, hundreds actually, depending on the coating and the substrate. Go to www.astm.org (http://www.astm.org) and do a search. Basically, for a marine environment, it is a heated box with bright lights and a saltwater wash system.

John E Hardiman
07-21-2003, 11:42 AM
Originally posted by NormMessinger:
How does one do an accelerated weathering test?There is an ASTM standard, hundreds actually, depending on the coating and the substrate. Go to www.astm.org (http://www.astm.org) and do a search. Basically, for a marine environment, it is a heated box with bright lights and a saltwater wash system.

Scott Rosen
07-21-2003, 11:45 AM
Originally posted by W Hersey:
I'm sure it is a great product for certain uses, but under exterior varnish on teak, the jury is out. I'm not convinced.

BillI've used it under paint, and I'm extremely pleased with the results. It improves adhesion tremendously.

I've also used it to treat rotten sections of plywood and small spots of rot in spruce and teak lumber, and it's worked great for that, as well.

I've never had problems getting varnish to stick to teak, so I don't need the extra adhesion there. But I have noticed that a sealer coat or two of CPES is easier and faster to apply than varnish sealer coats, and the CPES fills the grain faster. Balance that against the muted grain appearance, and make your choices.

Scott Rosen
07-21-2003, 11:45 AM
Originally posted by W Hersey:
I'm sure it is a great product for certain uses, but under exterior varnish on teak, the jury is out. I'm not convinced.

BillI've used it under paint, and I'm extremely pleased with the results. It improves adhesion tremendously.

I've also used it to treat rotten sections of plywood and small spots of rot in spruce and teak lumber, and it's worked great for that, as well.

I've never had problems getting varnish to stick to teak, so I don't need the extra adhesion there. But I have noticed that a sealer coat or two of CPES is easier and faster to apply than varnish sealer coats, and the CPES fills the grain faster. Balance that against the muted grain appearance, and make your choices.

Scott Rosen
07-21-2003, 11:45 AM
Originally posted by W Hersey:
I'm sure it is a great product for certain uses, but under exterior varnish on teak, the jury is out. I'm not convinced.

BillI've used it under paint, and I'm extremely pleased with the results. It improves adhesion tremendously.

I've also used it to treat rotten sections of plywood and small spots of rot in spruce and teak lumber, and it's worked great for that, as well.

I've never had problems getting varnish to stick to teak, so I don't need the extra adhesion there. But I have noticed that a sealer coat or two of CPES is easier and faster to apply than varnish sealer coats, and the CPES fills the grain faster. Balance that against the muted grain appearance, and make your choices.

JimConlin
07-21-2003, 05:57 PM
Here's a speculation, and i'll be happy if someone with more substantive knowledge turns up.

I gather that CPES is a heavily thinned epoxy and that when the epoxy cures, the solvent does not participate in the cure and is left, in a liquid state, within the solid epoxy. Over time, the solvent migrates out of the epoxy 'sponge', leaving voids. We do know that the cured CPES sponge has significantly degraded mechanical properties (strength). My guess is that its optical properties are also affected. I envision that varnish or epoxy (especially if applied to warm substrate) both cure to a clear, not spongy, solid and this is the reason the apparent color of the product depends on whether we're looking down into the wood's pores.

For what it's worth, I've been happy with the depth of finish i get when priming with epoxy. I do try to wait for warm conditions for primer coats. Of course, the world record holder in this is Robb White. That's another subject.

Jim

JimConlin
07-21-2003, 05:57 PM
Here's a speculation, and i'll be happy if someone with more substantive knowledge turns up.

I gather that CPES is a heavily thinned epoxy and that when the epoxy cures, the solvent does not participate in the cure and is left, in a liquid state, within the solid epoxy. Over time, the solvent migrates out of the epoxy 'sponge', leaving voids. We do know that the cured CPES sponge has significantly degraded mechanical properties (strength). My guess is that its optical properties are also affected. I envision that varnish or epoxy (especially if applied to warm substrate) both cure to a clear, not spongy, solid and this is the reason the apparent color of the product depends on whether we're looking down into the wood's pores.

For what it's worth, I've been happy with the depth of finish i get when priming with epoxy. I do try to wait for warm conditions for primer coats. Of course, the world record holder in this is Robb White. That's another subject.

Jim

JimConlin
07-21-2003, 05:57 PM
Here's a speculation, and i'll be happy if someone with more substantive knowledge turns up.

I gather that CPES is a heavily thinned epoxy and that when the epoxy cures, the solvent does not participate in the cure and is left, in a liquid state, within the solid epoxy. Over time, the solvent migrates out of the epoxy 'sponge', leaving voids. We do know that the cured CPES sponge has significantly degraded mechanical properties (strength). My guess is that its optical properties are also affected. I envision that varnish or epoxy (especially if applied to warm substrate) both cure to a clear, not spongy, solid and this is the reason the apparent color of the product depends on whether we're looking down into the wood's pores.

For what it's worth, I've been happy with the depth of finish i get when priming with epoxy. I do try to wait for warm conditions for primer coats. Of course, the world record holder in this is Robb White. That's another subject.

Jim

Wild Wassa
07-21-2003, 06:33 PM
Scott, I'm happy to have a guess as to why.

CPES penetrates the timber, deeply?, ... it sure goes somewhere. They (Smith and CO.) state/claim that the CPES imitates the structure of the wood's resin. So I presume that the wood's surface silicates are coated, so that their transmitance and reflectance of light, is reduced. Loosing that inner glow.

In photographic exposure terms, the wood on my own boat is now about 1 1/2 to 2 stops darker after applying CPES. Where as the density of the CPES, is equivalent to about 1/5 to 1/3 of a stop only.

Warren.

[ 07-21-2003, 08:11 PM: Message edited by: Wild Wassa ]

Wild Wassa
07-21-2003, 06:33 PM
Scott, I'm happy to have a guess as to why.

CPES penetrates the timber, deeply?, ... it sure goes somewhere. They (Smith and CO.) state/claim that the CPES imitates the structure of the wood's resin. So I presume that the wood's surface silicates are coated, so that their transmitance and reflectance of light, is reduced. Loosing that inner glow.

In photographic exposure terms, the wood on my own boat is now about 1 1/2 to 2 stops darker after applying CPES. Where as the density of the CPES, is equivalent to about 1/5 to 1/3 of a stop only.

Warren.

[ 07-21-2003, 08:11 PM: Message edited by: Wild Wassa ]

Wild Wassa
07-21-2003, 06:33 PM
Scott, I'm happy to have a guess as to why.

CPES penetrates the timber, deeply?, ... it sure goes somewhere. They (Smith and CO.) state/claim that the CPES imitates the structure of the wood's resin. So I presume that the wood's surface silicates are coated, so that their transmitance and reflectance of light, is reduced. Loosing that inner glow.

In photographic exposure terms, the wood on my own boat is now about 1 1/2 to 2 stops darker after applying CPES. Where as the density of the CPES, is equivalent to about 1/5 to 1/3 of a stop only.

Warren.

[ 07-21-2003, 08:11 PM: Message edited by: Wild Wassa ]

NormMessinger
07-21-2003, 09:29 PM
Wait a minute Rosen, if your varnish does not stick any better over CPES than it does over thined varnish why would it stick paint down any better?

NormMessinger
07-21-2003, 09:29 PM
Wait a minute Rosen, if your varnish does not stick any better over CPES than it does over thined varnish why would it stick paint down any better?

NormMessinger
07-21-2003, 09:29 PM
Wait a minute Rosen, if your varnish does not stick any better over CPES than it does over thined varnish why would it stick paint down any better?

Scott Rosen
07-22-2003, 07:25 AM
Norm,

I've never had a problem with varnish sticking to teak.

Before CPES, no matter what I did, I could never get paint to stick as well as varnish. For example, if I masked a painted area, when I removed the tape, some paint would always come with it--especially on teak. With CPES, the paint sticks and doesn't come off.

Maybe Chemist could explain why varnish sticks better than paint. I would guess it's because in varnish the oil and resin are bound together chemically (you don't need to stir varnish), while in paint, the solids are in suspension and don't bond with the wood.

Scott Rosen
07-22-2003, 07:25 AM
Norm,

I've never had a problem with varnish sticking to teak.

Before CPES, no matter what I did, I could never get paint to stick as well as varnish. For example, if I masked a painted area, when I removed the tape, some paint would always come with it--especially on teak. With CPES, the paint sticks and doesn't come off.

Maybe Chemist could explain why varnish sticks better than paint. I would guess it's because in varnish the oil and resin are bound together chemically (you don't need to stir varnish), while in paint, the solids are in suspension and don't bond with the wood.

Scott Rosen
07-22-2003, 07:25 AM
Norm,

I've never had a problem with varnish sticking to teak.

Before CPES, no matter what I did, I could never get paint to stick as well as varnish. For example, if I masked a painted area, when I removed the tape, some paint would always come with it--especially on teak. With CPES, the paint sticks and doesn't come off.

Maybe Chemist could explain why varnish sticks better than paint. I would guess it's because in varnish the oil and resin are bound together chemically (you don't need to stir varnish), while in paint, the solids are in suspension and don't bond with the wood.

doorstop
07-22-2003, 09:49 AM
Accelarated weathering test..... hmmmmm...... bolt the piece to be tested to the bonnet of an old car and drive through a carwash 52 times, park it out in the desert under the sun for bloody ages and then see how it and the car polish are both doing? ;)

doorstop
07-22-2003, 09:49 AM
Accelarated weathering test..... hmmmmm...... bolt the piece to be tested to the bonnet of an old car and drive through a carwash 52 times, park it out in the desert under the sun for bloody ages and then see how it and the car polish are both doing? ;)

doorstop
07-22-2003, 09:49 AM
Accelarated weathering test..... hmmmmm...... bolt the piece to be tested to the bonnet of an old car and drive through a carwash 52 times, park it out in the desert under the sun for bloody ages and then see how it and the car polish are both doing? ;)

thechemist
07-23-2003, 09:40 AM
Hmmmmmm.....much food for thought.

Scott----more experiments are needed to help others to understand what you are describing of what you observe.

Why not take a piece of glass and put some of your CPES on it, none and one or several applications as you did on your wood samples, and then varnishes as before?

Then, go to a building salvage place and get an old mirror, preferably one with really thin glass as older mirrors used to be. Repeat your varnish applications on that.

See if there is a difference in appearance.

I doubt the indices of refraction are that different for the various resins involved, and I think it more likely that second-surface reflection may account for the difference in appearance you describe, since the optical properties of wood are surely different from those of the resins, especially considering that the cellulose fibers are hollow, and filled with air having an index of refraction of essentially 1.0, compared to the resins that are likely twenty to thirty percent higher [higher by the square root of the dielectric constant].

Light is reflected in varying degrees from discontinuities in the index of refraction of media, depending on the angle of incidence of light. At some point one has total internal reflection, and such light scattered off the rough lower surface would be returned in part to the eye of the viewer. I don't know of any other physical phenomenon that may describe what you are seeing.

thechemist
07-23-2003, 09:40 AM
Hmmmmmm.....much food for thought.

Scott----more experiments are needed to help others to understand what you are describing of what you observe.

Why not take a piece of glass and put some of your CPES on it, none and one or several applications as you did on your wood samples, and then varnishes as before?

Then, go to a building salvage place and get an old mirror, preferably one with really thin glass as older mirrors used to be. Repeat your varnish applications on that.

See if there is a difference in appearance.

I doubt the indices of refraction are that different for the various resins involved, and I think it more likely that second-surface reflection may account for the difference in appearance you describe, since the optical properties of wood are surely different from those of the resins, especially considering that the cellulose fibers are hollow, and filled with air having an index of refraction of essentially 1.0, compared to the resins that are likely twenty to thirty percent higher [higher by the square root of the dielectric constant].

Light is reflected in varying degrees from discontinuities in the index of refraction of media, depending on the angle of incidence of light. At some point one has total internal reflection, and such light scattered off the rough lower surface would be returned in part to the eye of the viewer. I don't know of any other physical phenomenon that may describe what you are seeing.

thechemist
07-23-2003, 09:40 AM
Hmmmmmm.....much food for thought.

Scott----more experiments are needed to help others to understand what you are describing of what you observe.

Why not take a piece of glass and put some of your CPES on it, none and one or several applications as you did on your wood samples, and then varnishes as before?

Then, go to a building salvage place and get an old mirror, preferably one with really thin glass as older mirrors used to be. Repeat your varnish applications on that.

See if there is a difference in appearance.

I doubt the indices of refraction are that different for the various resins involved, and I think it more likely that second-surface reflection may account for the difference in appearance you describe, since the optical properties of wood are surely different from those of the resins, especially considering that the cellulose fibers are hollow, and filled with air having an index of refraction of essentially 1.0, compared to the resins that are likely twenty to thirty percent higher [higher by the square root of the dielectric constant].

Light is reflected in varying degrees from discontinuities in the index of refraction of media, depending on the angle of incidence of light. At some point one has total internal reflection, and such light scattered off the rough lower surface would be returned in part to the eye of the viewer. I don't know of any other physical phenomenon that may describe what you are seeing.

paul oman
08-01-2003, 05:21 PM
Very interesting topic!

Pretty much all strip kayaks are varnish over epoxy and they look great. Varnish over epoxy was pretty common on the brightworks of boats on Galveston Bay when I sailed there too.

I might suggest one more test. No matter if you use CPES or make your equivalent with epoxy and solvent, continue coating the wood with non solvent thinned epoxy until you have a slick, glassy, varnish like finish. Then apply the varnish over this epoxy surface.... I would be very curious as to the color results - I don't have a clue how it would compare to your CPES only surfaces!

paul oman
www.epoxyproducts.com/marine.html (http://www.epoxyproducts.com/marine.html)

paul oman
08-01-2003, 05:21 PM
Very interesting topic!

Pretty much all strip kayaks are varnish over epoxy and they look great. Varnish over epoxy was pretty common on the brightworks of boats on Galveston Bay when I sailed there too.

I might suggest one more test. No matter if you use CPES or make your equivalent with epoxy and solvent, continue coating the wood with non solvent thinned epoxy until you have a slick, glassy, varnish like finish. Then apply the varnish over this epoxy surface.... I would be very curious as to the color results - I don't have a clue how it would compare to your CPES only surfaces!

paul oman
www.epoxyproducts.com/marine.html (http://www.epoxyproducts.com/marine.html)

paul oman
08-01-2003, 05:21 PM
Very interesting topic!

Pretty much all strip kayaks are varnish over epoxy and they look great. Varnish over epoxy was pretty common on the brightworks of boats on Galveston Bay when I sailed there too.

I might suggest one more test. No matter if you use CPES or make your equivalent with epoxy and solvent, continue coating the wood with non solvent thinned epoxy until you have a slick, glassy, varnish like finish. Then apply the varnish over this epoxy surface.... I would be very curious as to the color results - I don't have a clue how it would compare to your CPES only surfaces!

paul oman
www.epoxyproducts.com/marine.html (http://www.epoxyproducts.com/marine.html)