Author Topic: Does paint on 1.5 pound foam absorb a lot more resin? (15 pound 8'-6" sups)  (Read 4029 times)

magentawave

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A well known shaper told me recently that he has his 8'-6" x 31" x 4.5" sups (approx 125 liters) down to about 15 pounds doing no fancy stuff like carbon or bagging, etc.

Here is what he does:
-1.5 lb EPS - no stringer - sealed with spackle.
-Double 4 oz E both sides with all layers wrapped around the rails.
-8 oz Volan deck patch.
-No bagging.
-4 Futures boxes (+ 4 fiberglass fins).
-No color.
-No gloss.
-Full nose to tail deck pad.

He said one of the keys to a light board is to NOT paint the foam (even though it's been spackled) because painted foam absorbs a lot more resin.

I have never heard of such a thing so can anyone else confirm that acrylic paint on sealed/spackled 1.5 pound foam causes the foam to absorb a lot more resin?

Thanks
« Last Edit: August 08, 2017, 01:08:18 PM by magentawave »
Pluto Platter: 7-10 x 29.25 x 4.25 x 114.5 liters

anonsurfer

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I don't think paint affects the final weight except for the weight of the paint itself (very small relatively).  I think sealing and how many glass layers you use has a bigger affect on final weight.  Here's a data point for you:

Board 1: 
80L 1.5# EPS, Not Sealed, Not Painted.  Additional weight after glassing: +6.4lb

Board 2:
78L 1.5# EPS, Sealed with Z-Seal, Painted with Acrylics.  Weight of Paint + Z-Seal: 2.5oz.  Additional weight after glassing: +5.9lb
Home Break: Doheny
Tic Tac v3 (Hoglet): 6' 6" x 23" x 3.6" x 67L
Omni: 6' 9" x 23" x 3.75" x 68L
Tic Tac (OG): 7' 0" x 22.75" x 3.5" x 70L
In The Pink (Incoming): 8' 0" x 22.9" x 3.25" x 70L

Blackproject Surge S77 (Soft Flex Shaft, T-Grip, +0" OH)

magentawave

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I don't think paint affects the final weight except for the weight of the paint itself (very small relatively).  I think sealing and how many glass layers you use has a bigger affect on final weight.  Here's a data point for you:

Board 1: 
80L 1.5# EPS, Not Sealed, Not Painted.  Additional weight after glassing: +6.4lb

Board 2:
78L 1.5# EPS, Sealed with Z-Seal, Painted with Acrylics.  Weight of Paint + Z-Seal: 2.5oz.  Additional weight after glassing: +5.9lb

Your two board weights make sense but he was reeeeeally adamant in saying that painting the blank adds a lot more weight.
Pluto Platter: 7-10 x 29.25 x 4.25 x 114.5 liters

Dwight (DW)

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Go for resin tint if you want color

magentawave

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Go for resin tint if you want color

Does that mean that acrylic paint on sealed foam does absorb more resin? Also, do you have any tips for how to avoid getting streaks when laminating with tinted resin?
Pluto Platter: 7-10 x 29.25 x 4.25 x 114.5 liters

jrandy

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Sounds like you're reeeally being told a story by someone who does not want to deal with a painted board Magenta.

Anon's numbers shows savings of .5 pounds in glassing weight on the painted board. That gets you an extra 4oz x 6sqft fin patch out back, lammed and filled, or a doughnut and a one-size-bigger coffee before surfing, depending how you view overall system weight.

Vacuum bagging would save you 5-10% weight on lam resin and 6oz carbon fiber is, well, 25% lighter than 8oz 'Volan' and stiffer to boot, and would also use less resin. I just saw that they are spec'ing E for the 4 oz, why not up the ante to S-glass?

I don't want to imply that your person isn't skilled at glassing or that the question is not valid, but I detect a little opinion mixed in with their layup suggestions.

I enjoyed your last build, hope we get to see the next one.

PS My 165L 9'3" compsand windsurf board with 5 foot straps and pads is 20 pounds even.
« Last Edit: August 08, 2017, 05:15:28 PM by jrandy »
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eDUBz

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Sure paint will add some weight but I don't think enough for weight concern.


Maybe he doesn't want to screw up your board with his bad painting skills  :-\
@rf.boardworks

magentawave

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Re: Does paint on 1.5 pound foam absorb a lot more resin? (15 pound 8'-6" sups)
« Reply #7 on: September 06, 2017, 06:01:00 PM »
Thanks, guys. He is kind of a BS'er which is why I asked here.
Pluto Platter: 7-10 x 29.25 x 4.25 x 114.5 liters

magentawave

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Re: Does paint on 1.5 pound foam absorb a lot more resin? (15 pound 8'-6" sups)
« Reply #8 on: September 20, 2017, 06:11:47 PM »
Go for resin tint if you want color

Dwight, I started a thread here https://www.standupzone.com/forum/index.php/topic,32435.0.html asking how to avoid streaks with tint. We would all love to read what you have to say when you get a chance, please.  ;)
Pluto Platter: 7-10 x 29.25 x 4.25 x 114.5 liters

supsurf-tw

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Painting foam will not result in more resin being absorbed however when you paint you need to consider the weight of the paint which can add a good amount. Clear boards with 1lb foam and a light glassing schedule will be the lightest possible but durability suffers
Boards:

 
8-10 x 31 Egg
8-11 X 32 Double wing Fangtail Tom Whitaker
8-6 X 30 1\2  Inbetweener Tom Whitaker
8-4 x 30 Hyper quad Tom Whitaker (wife's now)
8-4 X 31 1\4.  Round (wide) Diamond Tail Quad Tom Whitaker
 9-4 X 30 1\2. Swallow Stinger Quad Tom Whitaker (ex wifes now)
10-0 Brusurf for teach

jrandy

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At 8'6" x 31" x 4.5" I am guessing 40 sqft surface area,
At 400 square foot per gallon that is 1/10th of a gallon
At 11 pounds per gallon wet paint and 65% non-solids that is .385 pounds dry weight or 6.16 oz or 175 grams.
Sound right with peoples experiences? Mix 20 oz wet to yield 6oz dry on the board?
http://pushheretosavealife.com/
Be safe, have fun. -J

anonsurfer

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On my last board (78L) the total weight added from sealing (Z-Seal) and painting was 2.5oz.  Based on this, +6oz for a larger 8'6" board seems about right. 
Home Break: Doheny
Tic Tac v3 (Hoglet): 6' 6" x 23" x 3.6" x 67L
Omni: 6' 9" x 23" x 3.75" x 68L
Tic Tac (OG): 7' 0" x 22.75" x 3.5" x 70L
In The Pink (Incoming): 8' 0" x 22.9" x 3.25" x 70L

Blackproject Surge S77 (Soft Flex Shaft, T-Grip, +0" OH)

 


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