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For those of you who are currently using this process with good results I have a few questions. What types of finishes are you using it under? And what is your process?

While I am an old Dutchman and thereby genetically resistant to change, I am willing to learn new tricks. After reading about this several times I decided to run some test panels the other day while I was spraying some repair jobs. I ran two panels, one Mahogany and one EIR. One coat nitro sealer, 2 hour dry time, fill with tinted DW compound ( actually covered entire board), 4 hrs dry time, sand back level with 220, second coat of sealer. This is similar to what I do with an oil based paste filler. The shrink back was almost instant. In fact after a 24 hr dry, aside from the color left in the pores, it doesn't look much better than what I would have gotten with just two coats of my high build sealer.

So what are you guys doing different?

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Well Howard...you basically got it down...
lets see, as me remember ...
its colour the stuff.
shove it in ,
let it dry,
sand it,
repeat then
splash it with something.


Oh ya...mix in some glue with the colour...helps prevent shrinkage.

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Audiences and dispensations on Thursdays ~ by appointment only.


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Filling with drywall compound is like a slower more labor intensive version of filling with pumice.

Lather, rinse, repeat. Eventually the pores will fill, but it will take a bunch of iterations.

-jd

I think Robbie O'Brian was the first to bring it to my attention. I didn't have a problem with it shrinking, but was unable to get it dyed dark enough so I abandoned the experiment.

Steve

On my FP and on woods with a lot of color variation I use epoxy. Under most of my lacquer I use a commercial oil based paste, similar to pore-o-pac. I get some shrink back with it but not like this. Was hoping to get away from the 24 hr dry time involved.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Pore 0 pac and epoxy work so well and are not that expensive so why experiment with joint compound? I used to do drywall installation and after working with this stuff I wouldn't want it near any of my guitars. I would use plaster of Paris before joint compound. Woodworkers and carpenters have used this stuff for this exact thing for eons. Piano makers have also used this technique too...mike

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Guitars, guitars and more guitars.

A few years back when I was just doing my own stuff I was single process and it was epoxy. But now that I am doing more repair and re-finish for other shops as well as finishing some guitars for others and my own builds, pore filling is a bottleneck in the process. Epoxy takes 2 days to complete as a process and I have about 2-2.5 hrs in each guitar to accomplish it. Paste filler takes 24hrs as a process and has a labor burden of about 45-60 minutes. I didn't expect the DW compound to improve on the labor part of the process over the paste filler but was hoping to cut down the dry times and be able to seal, pore fill, and seal all in one day and cut out some overall process time. I was basically looking to get things through the booth and into drying quicker. I have used plaster of paris, but only under opaque finishes.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Plaster of Paris should be fine under water clear finishes, you've just got to get the stuff into the pores and not sat on the surface. One of the criticisms of PoP by the old timers was that the pore filler turned a lighter colour over time. Probably why it's imperative to go very dark and use a permanent light fast dye.

Brian,
Have you tried TimberMate? It dries really fast, like 20 minutes, and it sands very easily. It is water based, water clean up, and any left over product can be re-used simply by adding water to reactivate/ rehydrate it. Plus, a little goes a long way because you don't have to apply loads of it.
I have been using it on necks for the last 3 or 4 guitars and it is super easy, fast, and simple to use. I have not used it on a box yet because I really like how z-poxy pops the grain. When I run out of z-poxy, I may give it a shot on a full box. I have used it under nitro and wipe on poly with great success.
Tony

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http://www.CostaGuitars.com
PMoMC

I still use the pore o paq but by adding a little naphtha and using a wool bonnet buffer you can fill a guitar in less time than you may think. CF Martin taught me this method and it sure does work. You know my number Brian.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

John, how do you use the wool bonnet? As a wipe rag?

I've used drywall compound as a pore filler per the O'Brien method. It seemed to work well. It took just a few hours to do two applications. There may have been some shrink back but it's hardly noticeable. If I use that method again I may go a third coat with longer wait time between applications. You really have to lay on the dye for it to color properly. It's a bit deceiving coloring it since the drywall compound is wet, it looks darker than it actually will be when it dries. I finished with shellac French polish.

I experimented with drywall compound and couldn't get it dark enough. Seems I'm not alone. I used TimberMate on my last guitar and it worked well, although it has a weird smell. I don't think it emits harmful odors, just rather strong. As Tony said, it dries quickly.

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George :-)

As long as we're on the subject.
We all know that there are many different ways to fill pores. Each has it's ups and downs.

In this case, Brian is looking for something that applies quickly and cleans up easily.

Might I suggest a medium viscosity CA, spread evenly and hit with an accelerant? Scrape back to bare wood and the pores should be filled virtually instantly done.

Like the O.P. I have been looking for the same cure-all.

The last couple builds, I used Durham's Rock Hard but was thinking of trying drywall compound on the next build.
Main issue with Durham's was the sand back was dirty, time consuming and wasn't friendly to maple bindings.

I did have good luck with Egg Whites and can't remember why I got away from that. Maybe will try that again. As I recall, I usually sanded back too far and couldn't bring myself to trust that any egg white slurry that wasn't completely gone was going to mess with the final tone color under lacquer. But that was by far the fastest pore fill I've used.

Medium Visc CA. I'm gonna give that a try too.

Good luck Brian,

Dave

To those who seem to be having problems getting their filler dark enough, dye is the wrong tint for this type thing. Dye works fine for creating shading toners and such in finishes but you need a good solid pigment to tone a grain filler of any type. I use pigments for all mine when they need colored, I am partial to Mixol's oxide pigments as they are easy to use and completely colorfast but any high quality pigment as used for tinting paint can be used.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

I used Cal-Tint II Lamp Black. Kept putting more and more in, but maybe I just gave up too soon? I don't know. Maybe I'll do another test panel and see.

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George :-)

It really does stink. Smells like a petroleum product, but it is water based from what I remember.

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http://www.CostaGuitars.com
PMoMC

huh...guess since I'm a stoopid smoker I never really noticed any unusual smell to timbermate...of course since I've used famowood as a wood filler for years (solvent based), work around painters too much for my tastes, etc., something would have to smell awful strongly before I had any real notice of it..timbermate does dry pretty darn quickly, and is so water soluble that you can wipe it away with a wet rag after it has completely dried (like days after)...has a nice consistency and spreads very easily

Famowood (pigment darkened as mentioned), rag and DA wipe to clear, spray sealcoat, 2nd coat of Famo if necessary. Very fast, tolerable shrinkage.

The drywall compound mixes like 20 minute hot mud will not shrink as they set up chemically. I've never tried it and don't think I will but that might be an alternative and it should sand just as easily.

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Thank You and Best To All

On the medium CA as pore filler, I know of one builder who does exactly that for a number of reasons (pore filling + sealing) and has immaculate finishes. Squeegees it on with a plastic card. I'll probably go that route myself, or mix up some sort of UV curing resin, when I start building again.

It definitely matters what drywall compound you're using, since they are formulated differently and can act very differently. I have used this DAP patching compound stuff (comes in a tiny little tub, like 2.5" round and 2" tall) that dries very quickly, like a few minutes, and doesn't shrink perceptibly. I can't see why it wouldn't work well on pores given that very large chunks of it seem to hold their volume.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

would it be possible to mix the drywall compound with natural earth pigments such a burnt umber?

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We are all in the gutter but some of us are looking at guitars.

I think we may have stumbled upon the recipe here. As Larry pointed out the setting type drywall compounds don't shrink much. I was using USG Sheetrock brand DURABOND 20 and had almost zero shrinkage. George and I had the same problem with color. I used dye and lamp black but could only achieve a dark grey. I trust that Brian is spot on with the pigments for coloring.

I am currently using CA and have no problems with the fumes as I use my downdraft sanding table for that operation.

The best filler I have used is McFaddens pore filler, which I think they dont sell anymore. Its basically fine mud. I would highly recommend a few coats of finish and or sealers/finish before pore filling. If you sand through it, you will get light and dark spots. The trick to all of it is to sand evenly no matter what you use. I think I am going to try Crystalac again on a lighter wood with more layers of lacquer to it don't soak in. Wet sand it down with 400 or so.

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Jason Moe
LaCrosse WI 54601