MIMF

Rockhard is still showing up as in stock in the few places I checked, so buy it while you can I guess.

One thing I found difficult with Rockhard was I could not keep it from skinning over in the can which meant straining it every time.

Thanks for your thoughts on P&L H38 and Epiphanes. I have good access to Epiphanes through my boatyard day job. Epiphanes and Captain's varnish are the two we use the most. I've never tried it on a guitar though, I'll do that.

Right: they've totally changed the formula of the Rockhard varnish: it's not a polyurethane, and takes at least a day to dry per coat. The P&L is no faster, but in the trials I did it looks better and seems to be harder.

There are two basic problems with water based finishes: the water, and what you have to do to the finish to get it into the water. Water based finishes are basically just normal finishes that have been whipped up in some water, the way oil is in mayonnaise. The finish doesn't need to have enough solvent in it to make it brushable or sprayable, so you can cut down on the VOC content. In theory, it should work just like a normal finish, but in practice it doesn't.

When you spread a water based finish on a wood surface, the first thing that wets the wood is the water. As the water evaporates the little droplets of finish come in contact with the surface, but don't wet it out as well as the straight finish would. The result is that water based finishes directly on wood have a 'veiled' look: you don't get the 'light' you do with a normal solvent based finish applied directly. The usual work-around for this is to put some sort of solvent based finish on as a seal coat: normally either shellac or epoxy. This helps, but a lot depends on the refractive indexes of the two coatings: if they're different, it still ends up veiled, only less so. The water based finish tends to be engineered to work with one or another base coat, so you'd better like what they recommend. I'm not a fan of epoxy, particularly as a finish, so that lets me out of some of the water based stuff.

You can't just mix finish and water, any more than you can oil and water. Mayonnaise relies on the lecithin emulsifier in the egg yolk to get the oil and water to mix, and water based finishes use emulsifiers too. In some of the ones I've tried it seems as though the emulsifiers stay in the finial film, and cause problems. Since they're there to help water wet the finish material, some of the ones I've tried have been very prone to becoming gummy from too much hand contact. This might not be a problem on kitchen cabinets, but on a guitar neck it's a drag. I had a couple come back after a year or so with the necks feeling like they were coated in chewing gum. In other cases, the emulsifier seems to have weakened the film. One type would go cloudy as soon as you tried to buff it, with the film seeming to be microscopically fractured. Another coat of finish would restore the look, but then you have to smooth it out again. I've also seen water based finishes that simply built up 'way too much, and formed a film that was gummy in texture, with very high damping.

I admit that it's been some time since I've tried a water based finish. I dislike the finishing stage enough so that I sure don't want to have to re-do an instrument because of a failure of the finish, and I've had too many problems with water based ones to want to take a chance. They keep working on them, and I'm told the newer ones are a big improvement, but given where they were when I tried them, they'd have to have improved a LOT before I'd try again. Shellac and a good oil-resin varnish seem fine to me right now, and at least I'm pretty sure of what I'm getting in the medium to long term.

As a Rockhard oil varnish refugee, I'm liking Epifane's varnish quite a bit so far, though I'm only on my second with it.

Pat

Alan, I've seen references to Brian Burn's pore filling technique but have been unable to find details online. Could you please give some tips?

Mario, any particular flavor of Epifanes? I see that they have a Clear Varish, Rapid Clear, Rapid Coat, Wood Finish Gloss, as well as a 2 part version. Also, if I recall correctly, you posted some pictures of the flooring in your house that you coated with Waterlox. Have you tried it on an instrument or have a recommendation for or against it?

Brian's pore fill technique is, I'm pretty sure, much the same as the usual French polish method, but faster. I just used it on a couple of guitars, and it worked well, so here's what I did.

First: the idea behind it is that you're filling the pores with a mix of pumice and wood dust, using shellac as the binder. You apply it with a pad, a little at a time. Good results depend on having the right balance of filler and binder: too little shellac and the stuff won't stick, too much and you end up with mud on the surface. Since the mud is more or less opaque, and hard to remove (it's got glass in it, which makes it hard to sand...) you really want to avoid that problem, so it's best to err on the side of too little shellac to begin with.

With that in mind, you make up a pad as you wood for FP: I like to use wool in the center and linen for the cover. Coarse linen works fine, and holds up better in the fill stage than finer stuff. I get too much lint from cotton.

Wet the pad with your shellac solution. In this case, start with some 2# cut shellac ( 2# of resin to a gallon of alcohol) and thin one volume of it out with two volumes of acetone. This makes a very thin mix of shellac. Put a 'spit coat' of this on the surface: enough to wet it all, but not so much as to actually form a film on the surface.

Put some alcohol/acetone mixture on the pad, and sprinkle a bit of #4F pumice on the pad. Allow the pumice to 'clear' (take up the solvent), and then start to work in into the surface using a circular motion. You should hear it grinding away. Keep adding solvent and pumice as needed to do the whole surface.

At this point, with any luck, the first area you did will be dry, and the surface will feel gritty with pumice. Put some more shellac on the pad and start working that area again. The binder will help to stick the dust in the pores, and you should start to make some progress.

From here it's a 'lather, rinse, repeat' sort of thing. If the pores look open, and there's grit on the surface, add some more shellac. If things are filling so that there's no grit around, and there is no mud on the surface, add some alcohol and pumice. If you get a patch of mud try to pick it up with the pad and move it to a dry spot. Ideally, what you'll see on the filled areas if you look at them in grazing light is shiny filled pores level with the surface and the wood in between is dull. When you get the whole ting to look like that stop, and get some fresh air.

Within a few hours, and certainly by the next day, evaporation of the solvent will cause the binder to shrink back, and the pores won't be level any more. You'll have to fill again. The trick here is to be quick: the longer you have alcohol in contact with the filled pores, the more they will swell back up, and then, of course, they'll shrink back again later. I try to go over the whole surface very quickly on each pass after the first fill, to minimize this. The first fill might take an hour or so, but each subsequent one might only take ten or fifteen minutes. Here's where the solvent mix shows to advantage: because it evaporates so fast you've probably done more of the filling on the first pass, and subsequent ones have less to do. I only did one or two follow up passes on these most recent guitars, and saw little or no shrinkage later.

If you're using a varnish finish, allow the fill coat to dry for a day or two, if possible, and then sand back to level with fine paper: I like to use 220. Note that the filled pores might still absorb some varnish, which will then shrink back and cause the pores to show. Usually that's just in small areas, and I simply go over them with a little CA, level back, and proceed.

Thank you Alan. I was trying to understand what the acetone brought to the party.

I'm with Mario on the Epiphanes.... I'm using the clear 'high gloss", I start out with a 1:1:1 with their accelerator [essentially added solids that make a pseudo "short oil" varnish out of a "long oil"] and their thinner (or really good turps). It is varnish, so extra drying time and a fair wait for any buffing...if you even want to.

I don't have spray capabilities so this is the best brush finish I've found to date... I will admit that I still FP tops,varnish back and sides.... and I use DemBart gunstock/checkering oil on the necks.

Mike J

Jamestown Distributors in Bristol RI is the USA source of the Epiphanes varnishes. I was talking with Austin Clark , noted mandolin maker, about these varnishes, as he has some good experience with the company. He told me to get the "clear gloss varnish" not the "clear gloss wood finish". The reason is the clear gloss varnish has a bunch of phenolic resin in it and the other doesn't.

I got a can of the stuff but have yet to use it. That should happen in a few days as I'm in the beginning stage of finishing a mandolin for the Healdsburg guitar festival. Currently waiting for the shellac sealer coat to harden a bit.

I have been doing the french polish in a spare bedroom...nice, dust free and convenient. I would do the oil varnish in my attached garage shop, what type of exhaust fan is recommended for the oil varnish? Explosion proof required? I would be brushing, not spraying but would rather err on the safe side.

See the following response from Pratt and Lambert regarding my question above.

7/16/2013 10:40:28 AM [Agent Note]
Hello Danny,

Thank you for contacting the Pratt & Lambert website.

Honestly, your basic exhaust fan will be fine. You aren't spraying our product, so there should not be any risk of sparking. Just make sure you apply our product somewhat away from the fan. Ventilation is key, in terms of the odor dissipating.

Thanks again for your inquiry. Good luck with your project. Please let us know if you have any other questions or concerns.

Sincerely,

Daniel
Pratt & Lambert Product Support


7/16/2013 10:18:23 AM [Customer Note]
Are you requesting literature? ? N/A

I will be using #38 for acoustic guitars, brushing or wiping, not spraying. What type of exhaust fan is required? Is an explosion proof fan required? Thanks Danny

Alan Carruth wrote:Right: they've totally changed the formula of the Rockhard varnish: it's not a polyurethane, and takes at least a day to dry per coat.

I'm curious when they changed and what major aspect of the change was. I think I bought the quart I just finished up was purchased in the fall of 2012. It seemed to dry pretty good, easily sanded in six hours. Not so any more eh? Too bad, I liked it for the first couple coats as it was a deep amber and gave great color. Too much so for a full five-six coats, I finished off with Captain's varnish which is more clear. Captain's can be sanded for recoating in about 8-10 on a good day.

What I've heard is that the old formula used a phenolic resin, and they can't get it any more.

If anyone is wanting a water clear, fast drying and incredibly tough, brush-able urethane finish I can recommend a moisture cure urethane floor finish. I get it in 4 oz bottles from U-40 as permagloss. The stuff will show witness lines until you get it level but I've been finding that just one or two coats is plenty in terms of protection if you have a level substrate. It will spray if thinned slightly but you need a booth or spray outdoors. It's no fun to buff so I don't try for a gloss if my topcoat isn't perfect. It won't skin over in the bottle but it will jell if any humidity gets in.

Waddy,
I went out to the Vermont Coatings website, but found nothing about a Polywhey formulation specifically for instruments. Is this something one has to write to them about?

I think you do have to ask for it specifically. I was told to order the Furniture finish, and to ask for the instrument formulation in the notes on the order.

Thanks, Waddy.

Tom, just as an FYI check out my thread about water based finish and glue lines. My question in that thread is borne out of my first use of Poly whey luthier's formulation. I will continue to update my experience as I sort out the issue I am having (hopefully I have it beat now).

Thanks,I'll pay attention and see if I have any glue line problems. Never heard of that issue before.