Hardening soft wood -any suggestions?

dean

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I picked up a couple bodies on clearance at GFS (extra 25% off), and I'm planning out what I want to do with them. One was a LP-style body that looks like it was tossed in a corner and forgotten about - it's a mess! But for $24, I thought I'd see what I could do. The other one was a Paulownia body Strat that I will experiment with. As most of you know, Paulownia is quite soft, and the big concern is getting the screws to anchor the trem system solidly. I plan on converting the body to a hardtail by using more dense hardwoods to fill the gaps. The bridge screws will hold better in that. But I would also like to do whatever I can do make the guitar body more dense. I've searched the different methods for hardening softer woods, but I haven't found a system that will allow the hardener to soak into the body - most describe the hardeners as being surface conditioners. Has anyone ever tried to harden a softer wood? How did you do it? Any suggestions for products that might work for me? I also wonder if I could use a a thinned-down hardener to allow it to soak into the wood more deeply? I know that all these mods to the body will add weight, but the unfinished body only weighs 1.1 lbs! Any suggestions are appreciated!
 

Rufus

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Probably not the ideal solution...but if you HAD to do it...

Possibly drill and insert hardwood dowels into the body large enough to sink screws into the dowels, to hold the trem screws.

Like I said, probably not ideal, but there are probably WORSE ideas.

I wouldn't think a wood hardener would penetrate much below the surface and into the body...but, what do I know???
 

bgmacaw

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I assembled this paulownia GFS closeout Strat body in early 2020. You do have to be careful with it because it is "self relic-ing". Mine has a few dents and minor cracks from my clumsy mishandling (look just below the bridge for the dent I made when I dropped something accidentally). I guess it adds character. So far as supporting the trem system it has done well. No screws have pulled out or loosened. I'm not a heavy trem user though and it's decked on this guitar.

strat-o-dan partscaster.jpg
 

teletimetx

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Not aware of a real hardening agent that can be done inexpensively for a single piece. PTYP (pressure treated yellow pine) is harder and heavier than ordinary shop pine, but not sure there’s anyone out there who would take a single piece?

How about saw the body in half, insert rough 3/4” (1” nominal) walnut slab, plane combined body back to thickness you can live with? Trim to shape and then rue the time you just wasted on this entirely inadequate suggestion.

Many bodies have been successfully made with Palownia. Maybe someone with real experience will pipe in.
 

nojazzhere

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I picked up a couple bodies on clearance at GFS (extra 25% off), and I'm planning out what I want to do with them. One was a LP-style body that looks like it was tossed in a corner and forgotten about - it's a mess! But for $24, I thought I'd see what I could do. The other one was a Paulownia body Strat that I will experiment with. As most of you know, Paulownia is quite soft, and the big concern is getting the screws to anchor the trem system solidly. I plan on converting the body to a hardtail by using more dense hardwoods to fill the gaps. The bridge screws will hold better in that. But I would also like to do whatever I can do make the guitar body more dense. I've searched the different methods for hardening softer woods, but I haven't found a system that will allow the hardener to soak into the body - most describe the hardeners as being surface conditioners. Has anyone ever tried to harden a softer wood? How did you do it? Any suggestions for products that might work for me? I also wonder if I could use a a thinned-down hardener to allow it to soak into the wood more deeply? I know that all these mods to the body will add weight, but the unfinished body only weighs 1.1 lbs! Any suggestions are appreciated!
For what it's worth, I assembled my #1 Tele-style in 2019 (so going on three years) with a Paulownia body from GFS, and I've had NO issues with screws not holding, or anything else. I admit it dents if you even look at it hard, but other than that, it's a very lightweight and resonant guitar. I finished it with Tru Oil, and often get nice comments and compliments on how the Tru Oil brought out the grain. See for yourself.......and good luck.
1652300813644.jpeg
 
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PhredE

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Two-part penetrating epoxy will work (I've used it on wooden boats).
(I include the link to show it is a real 'thing', and sold by commonly known distributors -- no affiliation.. etc. etc)

The standard process is to drill small holes and 'inject' the mixed epoxy into the wood. Using that method, you'll have to cover the holes after the stuff is injected -- FYI.
The stuff works well though. I've used it on boat hulls and cabins with great success. Seems to flow via capillary action and is very thin. It will seep and seek until it 'finds' all the voids and areas of lesser density in the wood.
 

Freeman Keller

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I have no experience with hardening soft wood but I do know that Ibanez built a few guitars with bass wood which is about as soft as you can get. I know they finished them in some sort of epoxy so the surface resists dings and scratches better.

When I pore fill I dilute my finishing resin (Zpoxy) with DNA and it soaks into the wood pretty effectively - I would be inclined to give it two or three coats of highly diluted resin. Screws could be oversized and soak some finishing resin or water thin CA into the holes, inserts and machine bolts would be even better.

As with any finishing experiment, practice on scrap.
 

Beebe

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Not what you are looking for, but Barite makes a surface coating hard as H E 🏒🏒.

I added Barite White pigment to shellac to make a semi transparent white. I couldn't sand through it with 400 grit on a 5" Bosch orbital sander. It was just polishing it!

You can find affordable Barite powder that is more of a tan color sold for use in oil drilling or industrial coatings.

It's a really dense material. You'll be amazed at how heavy it feels in the container.
 

dean

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Thanks for the suggestions, so far. As far as the cavity filling goes, I’ve always wanted a hardtail - I never used the trem on Strats I’ve owned (Teles are more my style). If I can’t do anything about hardening the wood, I’ll likely go with the hardest coating I can find. Like I said, this was so inexpensive that it’s the perfect foundation for experimenting.
 

Beebe

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Hard wax oil is a penetrating finish that hardens the surface of the wood. Dissolve Carnauba Wax in Turpentine and mix with pure Linseed or Tung oil. Dilute it with extra Turpentine to get the first coat to penetrate deeper.

You'll need either time or heat to get the wax to dissolve. Careful with heat around the Turpentine. Definitely a double boiler type situation.

Edit: I suspect that water popping the grain before applying the oil will also help with even absorption.
 
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Beebe

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Just posting ideas as they come: Beeswax is commonly used to lubricate and secure screws in softwood. It helps prevent the screws from ripping apart the wood. I'd go so far as to say it would be incorrect to the install screws into soft wood without it (or equivalent).

And be very careful with applying torque when screwing in. I'd go a little less tight than your instincts tell you to go and it'll probably be fine.

As an alternative to installing hard wood dowels where the screws go... I suspect that adding some hard wax oil to the insides of the screw holes could help strengthen the wood around the hole. It requires oxygen to cure, but it's probably ok if it doesn't fully cure or cures very slowly over the years. My gut tells me it won't bond to the screw... especially if the screw is coated with a non drying oil (like used in watches) or wax.
 

old wrench

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If you want to harden-up the whole body -

There are several products out there specifically for hardening wood

The only one that I've used myself is the Minwax stuff - The box stores carry it

I used it to stabilize the plinths on some old wooden columns that had a little bit of rot

It's very thin - like water-thin, and it soaks right in - it really does harden the wood



If it's just the screw holes that you want to harden up -

Assemble the parts like you normally would - but just lightly snug up the screws/fasteners

Back the screws out - then thoroughly wet down the screw holes with water-thin CA glue

If the wood really sucks up the CA - let it dry, then give it another application and let it dry.

Now you can re-assemble - but when you go to install the screws, first give them a reverse turn until you feel the screw drop into the original threads that they cut the first time - then just screw them down like normal - but don't go crazy with the torque

I've done this myself and it works pretty good for soft woods - reinforce the hole before you strip it out

I think most of time we tend to get a little over-zealous and end up over-tightening wood screws ;)

.
 




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