Which is less likely to cup on a 9" deep shelf, SYP or poplar?

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Forum topic by 404 - Not Found posted 08-30-2013 11:31 PM 1296 views 0 times favorited 11 replies Add to Favorites Watch
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404 - Not Found

2544 posts in 2577 days

08-30-2013 11:31 PM

I have a customer who wants long shelves made, supported by wooden brackets that use diagonal braces. The shelves and brackets will be painted white.

They are going to hold books and one of them is also longer than 8’, so man made board is out of the question.

My timber supplier has nice 10” wide 4/4 planks of SYP at 16’ long or there’s a few wide poplar 4/4 planks, 16’ long in the bale. Both are kiln dried and show no sign of cupping even though both are tangentially sawn.

Normally I’d make a shelf this wide by ripping a plank in half and gluing it together heart side up/heart side down to eliminate cupping. I don’t think there’s going to be the money in this little job to do that. Is it sufficient to have the shelf heart side up – and attached to the brackets with a screw in the centre to keep the middle pulled down flat? Or do I need to get my biscuit jointer out?

Which would you use?

11 replies so far

View kdc68's profile


2553 posts in 1884 days

#1 posted 08-31-2013 01:18 AM

Your statement says both the shelves and brackets will be painted white. IMO, poplar has the advantage over pine for painting. Pine will have knots and would be more work for you to prep them so they don’t show when the paint is applied. If you are buying pine that is as clear as poplar, you may be paying more for the pine

-- Measure "at least" twice and cut once

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3191 posts in 1476 days

#2 posted 08-31-2013 01:45 AM

I’m thinking poplar is more stable than pine to begin with.



Pine might be less expensive though

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1251 posts in 1662 days

#3 posted 08-31-2013 01:49 AM


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#4 posted 08-31-2013 01:51 AM


-- Perfection is the difference between too much and not enough.

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#5 posted 08-31-2013 02:01 AM

poplar seems like the popular choice here

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#6 posted 08-31-2013 02:04 AM

But, which is less likely to cup?

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#7 posted 08-31-2013 03:02 AM

It really depends on the direction of the growth rings ,plain sawn vs quartersawn,but for a painted project poplar will give the better result

View NiteWalker's profile


2736 posts in 2184 days

#8 posted 08-31-2013 03:07 AM

I use a good amount of kd poplar and have had little to no cupping, even on 8” wide boards. So I’d go with poplar. I don’t work with a lot of pine though, but like I said, no issues with poplar for me.

-- He who dies with the most tools... dies with the emptiest wallet.

View RussellAP's profile


3080 posts in 1894 days

#9 posted 08-31-2013 03:25 AM

If cupping is a concern, dado a small depression about 2” from either end of the shelf and screw in a flat metal bar. Keep it flush with the wood and you can paint right over it. Guarantee it wont cup in a bog.

-- A positive attitude will take you much further than positive thinking ever will.

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404 - Not Found

2544 posts in 2577 days

#10 posted 08-31-2013 01:15 PM

Poplar it is then, it’s a few euro less than the pine as well. Thanks for the input.

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Don W

18252 posts in 2175 days

#11 posted 08-31-2013 01:19 PM

I agree 100% with poplar being the better choice.

-- - Collecting is an investment in the past, and the future.

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