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equal number of coats on both sides?

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Forum topic by WoodNSawdust posted 03-31-2015 11:21 PM 747 views 0 times favorited 9 replies Add to Favorites Watch
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WoodNSawdust

1417 posts in 642 days


03-31-2015 11:21 PM

Topic tags/keywords: finishing water based finish

I am adding a shelf to the bottom of my workbench to hold miscellaneous tools and eventually a cabinet for the tools.

Normally we plane or sand equal amounts from each side of a piece of wood. We veneer both sides. We laminate both sides. And we finish both sides.

If I put five coats of water based finish on the top side, do I really need five coats on the bottom or would two coats be sufficient?

-- "I love it when a plan comes together" John "Hannibal" Smith


9 replies so far

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MrUnix

4232 posts in 1664 days


#1 posted 03-31-2015 11:26 PM

Absolutely need to put the same amount on both sides… otherwise it will be aerodynamically unbalanced and could present a danger to anyone passing close by.

- sarcastic mode off – :)

I can’t think of a single reason why you need 5 coats on the bottom unless you plan on flipping the shelf sometime in the future and want it to have the same protection.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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bbasiaga

757 posts in 1460 days


#2 posted 03-31-2015 11:48 PM

I have always heard that if you don’t have equal finish on both sides, it will cause it to cup/warp. Consequently I have always put equal finish on both sides, though not usually 5 coats. I guess the question is do those last 3 coats do anything to affect the permeability of the surface, or is it already fully sealed after 2 coats?

-Brian

-- Part of engineering is to know when to put your calculator down and pick up your tools.

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WoodNSawdust

1417 posts in 642 days


#3 posted 03-31-2015 11:58 PM

@Brian: your question mirrors mine. Is two coats sufficient to seal the wood and prevent cup/warp. I am using five coats because it will have tools dropped on it, I may place my tub of water on it while gluing up something on the workbench top, and there could be glue getting on it. Besides, at least my HVLP sprayer produces such a thin coat of finish five did not seem to be too thick.

@Brad: to make it aerodynamically balanced I would probably go with carbon fiber and some form of epoxy to coat each layer. Done properly you would never detect the shelf as you flew by ;-)

-- "I love it when a plan comes together" John "Hannibal" Smith

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gfadvm

14940 posts in 2155 days


#4 posted 04-01-2015 12:20 AM

I usually just apply 2-3 coats on the “non-show” parts but I do try to lay it on thick to try to seal the surface.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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jumbojack

1667 posts in 2089 days


#5 posted 04-01-2015 12:21 AM

What material are you using for the shelf?

-- Made in America, with American made tools....Shopsmith

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bonesbr549

1176 posts in 2532 days


#6 posted 04-01-2015 12:36 AM

I’m of the mind set, I “Seal” both surfaces, but the show face will get extra. As long as sealed you should be ok. Take a look at some real old antiques, and you will see diff on the show side vs the non show.

-- Sooner or later Liberals run out of other people's money.

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WoodNSawdust

1417 posts in 642 days


#7 posted 04-01-2015 01:44 AM

@JumboJack: Baltic birch plywood.

Is there a way of knowing for sure that you have completely sealed the surface?

-- "I love it when a plan comes together" John "Hannibal" Smith

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Ghidrah

667 posts in 687 days


#8 posted 04-01-2015 02:24 AM

As long as the side is covered it doesn’t matter whether its 1 or 5 coats moisture is restricted. 1 coat covers the rest is aesthetics. With rigid materials like laminate or hardboard against MDF or ply one needs to dupe the mat to prevent cupping because of dissimilar mat reacting to moisture and heat.

-- I meant to do that!

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jumbojack

1667 posts in 2089 days


#9 posted 04-01-2015 09:44 PM

With BB you will have no problems with a coat or two inside and as many as you like outside.

-- Made in America, with American made tools....Shopsmith

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