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At one time I thought it made more sense to label myself as interested in build rather than repair, but since I've had to repair everything I've ever built, the current label fits. Today I was sanding the pore fill (again) on #4 before getting ready to spray shellac sealer, and couldn't help but notice that I have a continuing problem with the final binder thickness; it's too thin in areas where I had to sand more to get thru the pores that were not as filled (on the sides). Makes me wonder if I should finish pore filling and sanding completely before starting the binding process.
Or else I should find an easier pore filling process than epoxy...? I think I went thru five layers of epoxy trying to fill all the pores on my first build with EIR...but then I wasn't thinning it until the last two layers, and this is my first time using West Systems epoxy. One thing I have learned is that process order is important, as is process improvement. Appreciate any inputs that might help a senior newby. Roy

Are you absolutely dead certain that your bindings are of relatively equal thickness before doing porefill?

Do you fare your sides before routing the binding channels?

In addition to what Ed recommends, what has helped me the most to keep the binding consistent is to over cut the binding channel by +.010” and bring the sides down to the binding, not the other way around. I want to say that John Hall recommended that the first time I saw it, but whoever it was, thank you!


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What do you mean by the above? If I understand what you said correctly, you shouldn't be sanding to get through pores that were not as filled. Pores that were not as filled need a second and possibly third coat of filler, depending on the type of wood.

Maybe I'm reading that wrong though.

You also shouldn't have to sand five times with epoxy filler. I've been using epoxy filler for years now and I've not had problems like what you describe. I'm wondering if there's something up with how you are assessing whether the pores are filled or not and when to stop sanding.

One thing I am sure of is that you shouldn't have to resort to installing the binding after pore filling the sides.

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I don't know what fare the sides means. I did sand them to make sure I didn't have any obvious dips in the sides before routing for the binding. I thought they looked pretty good, tried to check them as square w same result.

Set the bindings 10 thou deeper than the sides; I had heard that before, either forgot or didn't understand the benefit. That makes sense now. Yes, after mounting the bindings they were flush with the sides and original width, at least to my eyes.

I don't feel great about the epoxy process, I was using it non diluted at first, and felt like I had to sand thru the epoxy just to see where I was in terms of the pores. I did that 3 times and still felt like I had pores that needed more fill. Not a lot, but I thought I needed to get rid of all of them. That's when I thought I should dilute the next application and press more. Then I still had to sand thru it to make sure, and the last application was done the same way. I did wonder by that time whether the pores were filled enough that the shellac and/or lacquer could have filled them completely, but thought I might be sorry later if I left them. The tightest part of the waist bindings are now visibly more narrow. I think I should have started thinning after the first application of epoxy, and probably should have been trying to press the first layer down into the wood harder. I would have been quite surprised to hear some folks pore fill and then rout for the bindings.
So about all I know is to try pore filling and sanding some scrap EIR with the above method before the next build. I will recess the binding from now on. Thenks for the inputs all. Roy

Roy—

I can’t tell you what has been wrong with your process, but I can tell what has been wrong with mine, and what I strive to correct. If some of this sounds familiar, maybe this will be helpful to you.

1. I really need to have the sides be as close to done (not with pore filling, but in terms of being flat across and smooth along the length) as possible before I cut binding channels.

2. Once the bindings are installed, if I am doing any sanding of the sides, I have to be super duper careful to keep the weight of the sanding block AWAY from the binding. If the weight/pressure leans toward the edge, it is just too fast and easy to thin out the binding without blinking.

3. Too much leveling between coats of epoxy is a waste of time and material, and sand-throughs can make splotches. So, I have to stop myself from trying to completely level the early coats. They won’t completely level without sand-throughs. I have to let it build a bit before I try to completely remove every shiny spot. And again, keep the weight of the sanding block AWAY from the edge.

I hope that helps. Again, these are my shortcomings, but you might identify with one or more.

Don makes a good point in #3. If you sand the first epoxy application until all the shiny spots are gone, and keep doing that with the next coats, you'll just end up chasing your tail because you'll likely keep opening up new pores that then need to be filled. And then you set yourself up for further rounds of epoxy and sanding, etc. I don't know if that's what you have been doing. but if so, that would be one thing to change.

When sanding an epoxy pore filler coat, you shouldn't be sanding into the wood.

From what I've seen here, there are two main approaches that people use for epoxy fillers.

One is to sand the epoxy back to the wood (not into it) and repeat until all the pores are filled and the pore filler is leveled with the wood surface and is present only in the pores.

The other is to end up with a very thin coat of epoxy over the entire surface (because of the way it enhances the appearance of the grain). In that case you try to not sand through back to wood. You sand until the majority of the epoxy coat has lost its shine and there are tiny shiny dots (partially filled pores) left scattered around the surface. Repeat until there are no more shiny dots after sanding the epoxy. In my experience this happens with two to three coats.

I've done it both ways and they both work.

In case it might help, here's a photo of what I see when I sand an epoxy coat without sanding through to the wood. This was after the first coat. The sanded epoxy on the right has lost its gloss compared to the unsanded epoxy on the left and the shiny spots on the right are partially filled pores. This wood was sipo which had long, moderately deep pores that took three rounds to fill all the pores completely.

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I nearly quit building over struggling with pore filling. None of the SM stuff or LMI stuff that even was billed as what Martin used I could make work. Burlap and this and that it all added up to heartbreak and incompletely filled pores.

Then I read the article that was back then on LMI about using System III (or any quality epoxy) and micro balloons and my problems were solved. After that two coats always did the trick and it stayed in the pores and Bob was my uncle.

Then watching how professional finishers do it with epoxy and in one case a foam brush and it all made sense.

I always sanded back to bare wood with no issues and then did a 50/50 wash coat to pop figure and even out color. The way coat is optional but it sure makes the wood look purdy.

I got past it Roy and even though it very nearly made me quit building we do get past these things and then they are pretty much forgotten.

Listen to the guys (mean and women) here, epoxy is a good way to go it solved all my problems and you will do fine I am sure.

Epoxy is a great pore filler, stick with it, it’s worth it once you’ve nailed the process.

One thing - say you’ve done two epoxy coats and 99% of your pores are filled but there’s still a few tiny scattered open pores remaining. You could sigh and mix up more epoxy and coat it and wait for cure and sand the darn thing again

Or

You could grab a bottle of thin CA and drop fill those pores in a few minutes and move on with your build.

You could even just start spraying, assess the pores after a few coats are on and decide whether more fill is required or whether the finish itself is going to get you the rest of the way there. It’s no problem to drop an extra blob of nitro on here or there between coats.

The Carruth Scraper (Ultimate Scraper at Stewmac) with rounded corners, the large one, is what you need as well. You really should scrape before sanding. The rounded edge towards the binding. Lightly and with prejudice. If not careful, you could introduce gouges. This is how I avoid the bindings. A three inch (90mm Festool) ROS helps too. Hand block sanding ok but can introduce longitudinal lines. Really, its all in your learned technique.

Rectangular razor blades with hand rounded corners are very useful for small area work scraping. Taping some of the blade edge can help.

5" ROS can easily encompass entire side which puts excess pad flex on edges (you should never do that).

This sounds like a lot of advice for a singular job. But no one tool/technique will do it all.

Its funny how some people will say something that will stay with you. John Hall told me that almost anybody can assemble a guitar. Where the trouble arrises is in fit and finish.

Lots of good input here, thanks to all. It never occured to me that I didn't have to sand back to bare wood, but could use the epoxy as a levelled 'base coat'. Not really sure how I feel about that yet. I've looked at that rounded edge scraper, too. Just a bit pricy for my hobby budget right now. I still need to buy some of those bridge clamps with the mid clamp support thread before I try my first HHG bridge attachment. And I do need to build at least one more neck with a flow chart that makes sense rather than a willy nilly flow that drives silly repairs like my last one. I probably won't start the next guitar til the fall. But I will review these ideas before I start the prep processes. It's never boring or dull, and once in a while I actually feel like I've learned something that makes me just a little bit closer to confident. I am anxious to try resetting the binding on my next build. I think that may make a big diff. Again, Thanks. Roy

Sharp scraper is the way to go imho. The very best pore filler I have used is good old CA. Quick, easy and does a great job filling pores that don't pop out if you sand or scrape back to wood which is what I always do.

Second fav is Aqua-Coat. The AC is less expensive than CA and doesn't have the fumes. If you do CA be sure to be outside with good ventilation. A drop fill with CA here and there is okay inside.

In the end though the idea is to sand the filler BACK to wood not to sand wood. You should only be kissing it. Some as mentioned don't even sand back to wood if using epoxy. yymmv.

If you haven't already seen it, you might want to take a look at Hesh's tutorial on pore filling with epoxy. I followed his method on my first attempt and got great results. He used Z-poxy, but the tutorial applies to other epoxies as well.

http://luthiersforum.com/forum/viewtopic.php?f=10117&t=20320

Also, standard single edge razor blades are cheap and effective scrapers that work great for leveling epoxy.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Personally I prefer to glue the binding proud and level to the sides rather than over-cutting the channel and leveling the sides to the binding, since it's less total material removal. But I'm sure either way would work fine, especially with scraping, where you can more accurately concentrate material removal away from the edges than with sanding.

My favorite scraper is the 0.8mm here https://www.leevalley.com/en-ca/shop/tools/hand-tools/scrapers/32670-super-hard-milled-scrapers?item=05K3002
And buy the carbide burnisher while you're at it (excellent because it doesn't rust) https://www.leevalley.com/en-ca/shop/tools/sharpening/32643-veritas-carbide-burnisher?item=05K2030
Round over the corners on the scraper to eliminate the risk of scratching the wood and your hands.

I bought the Veritas scraper holder too, and one of those thick Carruth scrapers from StewMac, but in the end nothing beats a plain old card scraper held in the hands. 0.4mm thick is also nice to have if you ever need to work on concave surfaces like archtops.

I’m also a big card scraper fan. I have several of different thicknesses and make small ones and odd shaped ones from pieces of old handsaw blades. But I’ve got to say, that Carruth scraper has been seen in my hand more and more often over the past couple of years. Great tool.

Thanks for the reference to the 04 Hesh DIY about epoxy fill. There's so much info on this forum, but sometimes a search just brings up too much to find just what you need rather than other things that have all the words you used. OTOH, folks on this forum are always quick to help, even if it seems too simple for experienced eyes. On card scrapers, I'm doing much better with turning the hook, took me awhile. Thanks a lot folks. Roy

I would also try CA a pore fill. I use both CA and epoxy. And have had good luck with aqua coat as well. it takes three coats for the aqua coat fyi

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One more vote in favor of the card scraper. And I use Stanley knife blades instead of single-edged razor blades. Lots tougher and less chatter. I grind the edges round so I don't gouge with the edge of the blade.

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Peter Havriluk

If Carruth Scraper is beyond budget, a box of square razors will do. Round the corners.

I don't much think about whether I sand to wood or not. I generally get quite close while avoiding the binding. I can scrape that with a rounded razor. I seriously use razors more that the scraper. When my body is on the final approach, it tends to look quite splotchy. That is when I apply a 50/50 Expoxy/DNA wash coat. Evens it all out.

After first 2 or so coats of lacquer, I start to search for missed pore. I fill those with thickened lacquer. After that dries, rinse and repeat. THen more coats of lacquer. Then let it cure for a while, bumps and all. THis is my final surface prep. Scrape, level sand with 320-400. THEN spray away!

Everybody has their own approach No one approach is right for everybody. But the basics do apply: surface prep.

there is no such thing as a short cut in the finish process.
for best result you need to follow these simple rules
A sand sides reasonably flat before you rout binding channels.

B when routing the binding channel be just a tad lower so you sand side to the binding. The #1 error I see on beginner guitars is flaring the binding and thinning it so it looks uneven and pinched off from the face side. Sanding the side to the bind is more efficient.

C if sanded almost flat this final sanding will get you there and NEVER SAND WITHOUT A BLOCK

D Seal then fill and if you want to stain do that first.

E when filling read your label on the finish as to what is recommended. This is as much about chemical compatibility and technique. I have tried ca as a filler and found issues later in the guitars life. It can cause some adhesion issues. Super Glue is not a filler, its a glue. Fumes are not good to be around.

what I have learned in 25 years

it is hard to beat shellac , and I am talking about flake shellac 2 lb cut

fillers are tricky as you need to learn the technique of application. I tried just about everything out there. Pore o Paq is a mineral based filler and works well . Martin uses a very similar product. You can add stain to color it and the trick is to use a few drops of naphtha to aid in the flash time. I like using my ROS sander with a lambswool bonnet and scour it into the pores

Aqua coat this one is a no brainer , also able to color it. This wipes in well and I apply it with a latex or nitrile glove and rub in , working a side at a time and doing the back. my process is simple splat , rub then use a 5 in squeegee or a credit card and cut it diagonal across the grain. I allow about 2 hr between applications. I do 2 let dry sand with 400 then apply another coat . Let set overnight sand and seal.

using Nitro , if you are using vinyl sealer , shoot a coat of lacquer right away on top of the sealer for a better adhesion.

there are plenty of ways to do this seal and fill part but find the technique that works for you. Building a nice guitar isn't hard making it pretty is a lot more work. If you skimp on the prep don't expect a good result. PATIENCE

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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, anything I said that was wrong, plz correct. I'm never too old or too good to learn. I take all of your advice to heed.

Mike

John, what kind of color is compatible with Aqua Coat?

I’ve used SM Colortone stains with good results.


Steve

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Steve Smith
"Music is what feelings sound like"

I have used the transtints jeff jewitt puts them out. The Stew mac stuff is jeffs too I think

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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

Trying to do some delam nitro repair on #2. I have it prepped to 150; getting ready to spray shellac. I dunno cuts, so I mixed 3 gm of flake w 6 gm 99% alcohol. Looks quite sprayable. So if I spray shellac (is there a best temp range for the mixture?) and don't immediately plan to spray any lacquer, is there any particular treatment I need to give the shellac before I do a first nitro? And should the first coat be thinned? Appreciate any inputs, and thanks John for the prep outline. I'll be glad to keep that handy next time. Roy