Friday, April 17, 2009

A Whiter Shade of Pale

David Heath (alegria_1976) of the Ingrid 38 Group has posted a very interesting discussion of how the choice of paint color can affect the temperature of a boat:

Janet & I have spent many years in tropical areas in our boat. In 1993 a very nice engineer at AwlGrip (International Paints) gave us some amazing information about which paint is cooler in the hot sun and how much cooler. In the chart below, notice that G8044 absorbs about 3 times as much heat as G8001. This translates that if G8001 in the sun is 5 degrees hotter than the temperature in the shade. G8044 will be about 15 degrees hotter than the temperature in the shade. Dark colors can actually melt some plastics.
When we had painted part of the deck. We could easily walk bare foot on the G8001, but our feet (toughened by years of going barefoot, often on hot sand and hot concrete, could NOT step over onto the G8044. We'd hop over it like a frog in a skillet.
We noticed that our boat was much cooler in the summer sun after we painted it with AwlGrip G8001 Pure White. Glare is not noticeably different. There is glare, but no worse than the hotter "whites".
This table below is from 1993. Perhaps some of the colors are no longer listed by AwlGrip. With some paint companies, they change the color of a paint, but do not change the name or number. Woolsey Paints did this to us in about 1985. This caused us a LOT of trouble and expense and I hope that AwlGrip & International Paints is much smarter than Woolsey.
Here is what I got by email from Awlgrip about availability:
G8001 Pure White is still available, but is no longer considered a `standard' color. It can be purchased through any of our distributors that are set-up with the Awlmix system, or can be ordered from our Union, NJ warehouse by those distributors that have chosen not to participate in Awlmix. Your assumption is correct in that it is straight white blending paint Q8154 that is used as the base for mixing colors.
We have been using AwlGrip since the early 1980s and we like it. But, there are many good paints. All I am trying to say is that some paint colors make a BIG difference in how comfortable you are when it gets really hot out.
Also, In the 1980s we felt that AwlGrip primers were NOT doing the job for us and stopped using them. We used WEST epoxy, but long ago switched to System 3. AwlGrip works great over either WEST or System 3 and probably over any excellent epoxy.
HOWEVER, if you have not already noticed. Paints and resins and sealants are tricky stuff. I STRONGLY encourage you to use ONLY a single system, know to be compatible and follow the directions. 47 kinds of Hell can descend upon those who do not.
Putting incredibly expensive bottom paint over the wrong equally expensive primer or old paint can fall off in a week or all turn to cottage cheese or some other nightmare.
Be suspicious of what I tell you and any other pundit online or in the haul out yard. But, we believe that in the above, even the manufacturer did not know.
Back in the 1970s, our first 2 part Linear Polyurethane Paint was only sold industrially. But, we bought some. The 2 part primer instructions said to mix the clear hardener with the yellow base. Our base was gray. We phoned them and they went out into the warehouse and opened several cans. All were gray. "Its OK. Go ahead."
But it did not get hard. We called again and were transferred to the head chemist. He was astounded! "WHAT! The base is yellow, not gray. I will call you back."
A few minutes later he called back, with the bad news that ALL of their cans of primer had the wrong label.
They gave us new primer, but we got to drive 50 miles to get it and spend hours cleaning the crud off of the dozens of parts that we'd painted. It was a sad day in Muddville.

He also included a table of the reflective properties of AwlGrip colors. Any color is cool as long as it is Pure White.

Number Color % Reflects % Absorbs
G8001 Pure White 95.47 4.53
G8044 Snow White 86.43 13.57
G8029 Blue Tone White 86.14 13.86
H8010 Oyster White 84.14 15.86
G8003 Matterhorn White low 80s abt 17
G8010 Off White 81.98 18.02
G8004 Vestal White 81.03 18.97
G8022 Insignia White 80.21 19.79
G8009 Off White Revisited 79.47 20.53
H8087 Fleet White 79.38 20.62
H5004 Ice Blue 78.30 21.70
H8002 Cream 78.06 21.94
H8015 Egg Shell White 77.22 22.78
G9059 Tender Yellow 74.67 25.33
H8086 Chevy White 74.45 25.55
G8036 Etherial Blue 71.11 28.89
H5002 Beyonda Blue 71.04 28.96
G6004 Moon Dust 62.20 37.80
G9001 San Mateo Wheat 61.84 38.16
G8035 Whisper Gray 59.65 40.35
G1040 Graystone 58.26 41.74
G1008 Pearl Gray 57.40 42.60
G1001 Light Gray 47.60 52.40
G1009 Kingston Gray 44.69 55.31
G6002 Desert Sand 42.58 57.42
G6003 Prairie Beige 41.65 58.35
G6006 Castle Tan 41.57 58.43
G1007 Medium Gray 33.80 66.20
G5036 Bahama Blue 27.89 72.11
G1002 Dark Gray 19.44 80.56
G579 Electric Blue 14.75 85.25

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