Which Screws Won't Cause Bleed through on Wood Filler For Bookcase

[bostonman]

I"m building a bookcase with dados and using Poplar wood (1 and 1/16" thick). I plan to screw the shelves and countersink the screw heads along with filling them with wood putty (?) to cover the holes and then clear stain.

I'm uncertain which screws to use. Not necessarily because of wood splitting or anything (I plan to pre-drill the holes to minimize the risk of cracking and/or screws stripping), but more about whether the material from a screw will bleed through over time.

The only screws I have are the yellow Deckmate (construction ?) from Home Depot which I planned to use, but concern on whether that finish will breakdown over time bleeding through the stain.

Does anyone have recommendations?

[David Hess]

I like the GRK screws which are available from Home Depot because they are rated for structural loads and use Torx drive, but they also come in a finishing trim head version.  They are plated/coated to prevent bleed through, but the sure solution is to use stainless steel screws.

[PlainName]

If this is indoors, is there any real problem with type of screw so long as it's strong enough? Extremely unlikely to corrode, particularly since you'll be sealing it in.

When I built my office I just used whatever was a good price at Screwfix (kind of UK Home Depot in a loose way). Twenty years later nothing has fallen apart, and when I do look at the original screws they look just like they did then. OTOH, same screws outside and you know they've seen weather, so they're not particularly anti-corrosion.

[I wanted a rude username]

The surface finish itself is not a concern, corrosion of the bulk steel of the screw is. This shouldn't be a problem for bookcases since they must never get wet. But it could happen.

They type of surface finish is often less important than how well it's performed. Chrome and zinc are both pretty good for dry environments but in adverse environments I've seen separate examples of both chrome and zinc coated parts be either really resistant (basically no rust ever) and also extremely rust-prone.

Your best option might be either to find screws that actually have some kind of salt spray resistance rating, or stainless as David Hess suggests (and then you also want a rating because some "stainless" just isn't). You also won't need to cover them with putty, as they'll look good exposed.

Also consider the psychological perspective: if you're building a once-off, it's nice to use high quality components because then every time you look at it you'll be reminded of how good it is.

[Ian.M]

Don't  cover them with putty/filler - that's just fugly under a clear finish.  If you want to do this properly, get a plug cutter set and cover them with cross-grain plugs cut from the same wood as the rest of the bookcase, with the grain aligned.

[themadhippy]

dab of rust proof primer on the screw head if your really worried

Don't  cover them with putty/filler - that's just fugly under a clear finish

cheapskate method is to mix the sawdust youve gained from all the cutting and drilling with a bit of wood glue,If you use a clear glue like cascamite its almost invisable

[Benta]

And the pro way is to use dowels and glue.
No reason for filler, it's invisible when done correctly. Not really possible to do with a hand drill, you need a drill press plus additional tooling.

[TimFox]

Dowels and glue greatly increase the strength of the joint.
A Japanese "nokogiri" handsaw is ideal for cutting the dowel after hammering in place:  sometimes the result does not even need sanding to be flush.
However, a recessed screw (head covered by a wood plug) helps to hold the two pieces together, relieving shear on the glue.

[Gyro]

The other method is to use pocket screws, with associated jig. These are invisible from the outside, the screws going outwards at an angle through the bottom surface of the shelves through neat oval 'pockets'. The screws are a specific type, taking that decision off your hands.  I can't say I'm a great fan, but they seem to be the modern thing.

eg:  https://www.familyhandyman.com/project/how-to-use-pocket-screws/

[T3sl4co1l]

Drywall screws are fine.

Tim

[TimFox]

Specifically for bookcases, when loaded, I have found that there are substantial forces tending to push the verticals outwards, stressing whatever demountable fittings, screws, dowels, or biscuits are used to hold the horizontal shelves in place.
Dowels are good for fighting the vertical forces, and screws are good for fighting the horizontal forces;  choose a good combination.
For my constructions, I use flat-head screws (I prefer Robertson square-drive heads) with wood plugs over them and glued dowels between the screws:  the plug and dowel diameters match and cannot be distinguished externally.

[jpanhalt]

In 1970, I built a large bookcase with 3/4 inch veneer core birch plywood.  Shelves were also 3/4 and were supported on adjustable standards dadoed into the sides and verticals.  It was approximately 84" tall x approximately 120" wide (4 columns, 30" wide).  The standards were attached with  ordinary FH wood screws short enough not to penetrate the sides and verticals.  It has been packed with books and survived more than 50 years.  One thing I discovered is  not to exceed 30" width for a shelf less than 10" deep.  If you want deeper, increase the thickness.

[bostonman]

I looked into pocket screws and various options.

My main question/concern was which screw(s) can possibly bleed through wood fill (I am aware pegs may be a better option).

I'll figure out which option I'll go with, but I have already bought wood fill, but, as I said, it was a question more about bleeding through than options. Also, this bookcase will be suspended with threaded rod. The dados are more for look since the rods will support the shelves.

The wood (as mentioned) is Poplar, 1 and 1/16" thick, 11.25" deep, approx. 48" wide, 12" between each shelf , five shelves (six if you count the top which will be against the ceiling), and a computer model (done by a former mechanical engineer co-worker) shows that the threaded rod should be placed approx. 12" from the edges for ideal support (at least that's what I believe is the distance based on the study he did - see attached - it's been a few years since I went over this with him).

Without including the weight of the wood, I currently have about 300lbs of books. Some math helped by the former mechanical engineer at work showed that x2 5/16" (one on each end) should be more than enough to support triple my needs; and I may go with 3/8" or 7/16".

[David Hess]

Drywall screws are fine.

I stopped using drywall screws after having some break, and they are the worst for rusting and bleeding through.  Unlike construction screws, they are not specified for live loads.  I suspect the problem is that they are not heat treated to prevent work hardening, but maybe it is just a problem with cheap material selection.

One thing I discovered is  not to exceed 30" width for a shelf less than 10" deep.  If you want deeper, increase the thickness.

It is not as pretty, but a strip can be added along the edge underneath a thin shelf to strengthen it preventing sagging under load.

[jpanhalt]

Even with 1-1/16" poplar, a 48" wide shelf may sag, particularly if loaded with heavy books (e.g., 10" deep).

I used standards and clips to get adjustable shelves.  I would probably not do that again, as once set up, we rarely if ever adjusted them.  It was generally more appealing to have the shelves line up across the face.*  Thus, rather than end screw the shelves from the outside, I would use cleats on the inside.  That allows shelves to be removable with no hardware showing.  If you want a more rustic look, I would not use a wood fill, but rather use either domed wood plugs or dowels  cut flush and sanded.  Dowels cut and sanded are considered by some to be an additional artistic touch.

*A curio cabinet I built, on the other hand, was intentionally designed with short shelves at multiple levels and not lined up side to side.  The purpose was different.  A bookshelf to me is functional over appearance.

[T3sl4co1l]

Drywall screws are fine.

I stopped using drywall screws after having some break, and they are the worst for rusting and bleeding through.  Unlike construction screws, they are not specified for live loads.  I suspect the problem is that they are not heat treated to prevent work hardening, but maybe it is just a problem with cheap material selection.

IIRC, they're somewhere around 1045 steel, which doesn't really harden, but still hard enough that it tends to snap rather than bend.  They're good for some strength, but to be fair I should've said deck screws -- or I suppose that includes the "construction" kind -- essentially same style, but made for it, properly tempered (hm, I don't know what alloys, actually), and coatings to reduce friction and corrosion.

Main thing is, just avoid those traditional/old style tapered screws: mild steel, huge friction, half of them strip out before even getting flush, even with pilot holes.  Man I hate those things...

It is not as pretty, but a strip can be added along the edge underneath a thin shelf to strengthen it preventing sagging under load.

Yep, greatly saves on material.  The sides are braced by the shelves so don't need much any stiffening, but the shelves themselves benefit from a flange or beam along them.  Doesn't have to be at the front (though, that may be the most convenient mounting place), and doesn't have to be wood either -- indeed, if you need to save vertical height, or weight, consider an exceptionally stiff material (in comparison), like steel!  Just mount it in such a way to avoid expansion issues -- drill slotted holes for example.  Hot-rolled flat (mounted flush to the face) or angle (mounted face or underneath) would do well, and has a soft corner safe for touching; it might be worth sanding and varnishing/painting before assembly to get a more pleasant finish.

Even aluminum is a great improvement, though you need more of it (although, less by overall weight, if you can afford the increased vertical space).

Tim

[PlainName]

In one instance I solved the problem of long shelves by putting a fake vertical leg in the middle (both length and widthways)

It was actually just several sections (to avoid making holes in the shelves) so the top shelf pushed on the next one down, all the way to the floor. Sounds terrible but actually useful as bookends. I suppose, if some equipment instead of books were on there, each support could be moved over a bit to give space, but it would spoil the effect of a square post exactly fitting square holes through all the shelves

[madires]

You can get special wood construction screws, e.g. SPAX, plus covers (plastic caps).

[David Hess]

Drywall screws are fine.

I stopped using drywall screws after having some break, and they are the worst for rusting and bleeding through.  Unlike construction screws, they are not specified for live loads.  I suspect the problem is that they are not heat treated to prevent work hardening, but maybe it is just a problem with cheap material selection.

IIRC, they're somewhere around 1045 steel, which doesn't really harden, but still hard enough that it tends to snap rather than bend.  They're good for some strength, but to be fair I should've said deck screws -- or I suppose that includes the "construction" kind -- essentially same style, but made for it, properly tempered (hm, I don't know what alloys, actually), ...

I was looking for non-Philips/slotted drive construction screws for use in an overhead safety application (1), and what originally caught my eye is that GRK provides bending, shear, and tensile strength in their datasheets.  They also make the same screws in with finishing trim heads and stainless.

It is not as pretty, but a strip can be added along the edge underneath a thin shelf to strengthen it preventing sagging under load.

Yep, greatly saves on material.  The sides are braced by the shelves so don't need much any stiffening, but the shelves themselves benefit from a flange or beam along them.  Doesn't have to be at the front (though, that may be the most convenient mounting place), and doesn't have to be wood either -- indeed, if you need to save vertical height, or weight, consider an exceptionally stiff material (in comparison), like steel!  Just mount it in such a way to avoid expansion issues -- drill slotted holes for example.  Hot-rolled flat (mounted flush to the face) or angle (mounted face or underneath) would do well, and has a soft corner safe for touching; it might be worth sanding and varnishing/painting before assembly to get a more pleasant finish.

An I-beam type of construction would be ideal for saving weight, but I settle for something like a 1x2 wooden strip along the bottom of the front edge so that it does not take up too much vertical space.  It would work better if set back slightly, but I prefer for it to be fully visible.  I am sure you know this, but for others, moving the edge of the strip further away from the center of bending places more strain on it so more force is applied to restore the bending, so extra thickness has more effect than extra width, which is why i-beams use that shape.

(1) A wooden stairway collapsed under me because it was held in place with only friction from overhead *nails*.  WTF!  Yea, government building inspectors and permits are about safety.  *rolls eyes*

[bostonman]

From reading the replies, it looks like the yellow Deckmate screws could bleed through over time.

I'm better of with stainless steel then?

[Ian.M]

Poplar is one of the preferred woods for sword sheaths because it doesn't have high enough tannic acid levels to corrode steel in a reasonably dry environment.  Therefore I think that unless you live in a tropical swamp, it is highly unlikely  that even uncoated plain steel screws will cause significant discoloration round them for more decades than any of us are likely to care about.   However, dip the screws in boiled linseed oil or varnish and drive them wet, and they will be significantly protected against corrosion, drive easier and hold better.

The highest risk of staining is from the plastics and resins in modern wood fillers degrading . . .

[bostonman]

The highest risk of staining is from the plastics and resins in modern wood fillers degrading

Ironically, wood fill is most likely the way I'm going. I know it may not be the prettiest, but it's the direction I'm planning to go.

My initial concern was whether the chemicals on the screws would begin deteriorating into the wood fill and then be exposed. Seems like maybe I don't need to worry as much as I do the wood fill.

[AndyBeez]

You can make a 'cheat filler' by mixing PVA wood glue with dust from the wood you are filling. Simply collect up the wood sandings. At a glance the color match can be pretty good. PVA is also reasonably inert to metal fixings if kept dry.

[jpanhalt]

I still don't see why you want a plastic wood filler rather than dowels sanded flush.  Look at any fender bender repaired with "Bondo" vs. old fashioned, skillful bumping and just a little lead 10 years later.  The plastic always shows.

End screws in the shelves will be strong enough, but your bookcase cannot be taken apart for moving.  In other words, it will become a fixture in the house.  Why not build it on the wall?

[bostonman]

Why not build it on the wall?

Without increasing support, I wouldn't trust the wall beams.