Done With Nitro....going To Wipe On Poly

[madhattr88]

Up til this point I pay someone to spray my solid bodies with nitro cellulose. I don't like it, sure it looks great, but it chips and cracks during the final assembly process. (Hardware, neck fit, etc). Not to mention he raised his prices to $300. So I will be finishing them myself. The only spray system I have is a pre-Val unit. I have searched everywhere for info on wipe on poly and I'm currently reading Flexners book. Instead of starting from scratch and experimenting, I was hoping to find some luthiers on here that can give me a few tips. Any polyurethane guys out there?

I tru oil the necks. So I'm just looking to get a high gloss on my bodies.

Thanks!!!

[killemall8]

Nitro is the worst idea of a finish ever invented, if you ask me.

I have shot poly for years. I spray it though, i have never done a wiped on finish.

[curtisa]

My last few builds have been wipe-on poly. Like you I'm limited by the equipment that's available to me (or rather the lack of it), so I have to use alternative methods of finishing.

It's reasonably hard wearing provided you build it up, which will take much longer than spraying. It's not as hard as nitro, but a lot more durable than oil. I usually bank on two coats in 24hrs in warm and dry conditions. If it's cooler I'll do one coat a day. I'll generally aim for 12-14 coats total, and then leave it about a month to cure properly before polishing, assembling and playing.

Use old cotton T-shirts or similar lint-free material as your application rags and expect to go through a lot of squares of rag material before you're done. Don't try to use the rag more than once. When the poly dries on the rag it will go like cardboard. Place used, wet rags outside laid flat on the ground when you're done applying a coat, as the poly is exothermic and can ignite a rag if it's screwed up and placed in an enclosed space. Wear rubber gloves too - since the poly is almost water-thin it soaks through everything. I use those disposable latex single-use gloves that Ansell make in boxes of 100 pairs. If you have the body mounted on a post in a vice, or suspended from the ceiling you can get away with only one glove and make the box last twice as long.

I usually do light coats to start with, just placing the rag over the neck of the container and inverting the contents briefly to wet the rag enough to get the poly on the instrument. Doing heavy coats early on looks really good initially but seems to increase the drying time between each coat, and the finish devleops a rubbery feel that takes a while to cure out. Once I have about 4-6 light coats on I'll start applying heavier coats. I'll tip a small amount of poly into a small tub and soak the rag in the mix, squeezing the excess out before applying it to the instrument.

Lightly kiss the instrument with 600-800 grit paper between each coat for the earlier stages, just enough to remove any surface imperfections and dust nibs. I've found that you can use much lighter grit sandpaper when you switch to the latter heavier coats, or even skip sanding between every altenate coat. Steel wool or scotchbrite saucepan scourers can work too if used lightly, just remember to go over the instrument with a clean cloth after sanding/scrubbing/scouring and remove any steel wool shavings, dust or scuzz before coating again.

A light touch with the rag makes application relatively simple and foolproof. Aim for long sweeping motions in one direction only, overlapping each pass slightly as you go. When you hold the body up at various angles in the light you should be able to see how you're progressing and if you've missed any spots. If you can avoid it don't go over the same area more than once while wet, as it's difficult to get the edges to re-blend once the initial coat is down. If it looks like you've missed a bit or it's drying a bit patchy, just let it dry and fix it up in the next sanding/coating run. Depending on your timber choice you may find a couple of spots where the poly dries slightly differently to the surrounding areas (usually this shows up as a dull patch that suddenly appears when doing the sanding between coats). Again don't sweat it, as you build up the coats this will eventually blend in to the surrounding finish.

Watch for runs as you apply the finish. If you do light coats early on runs probably won't occur. During the heavier coats you can get a run, but if you remember to squeeze out the excess and blend your edges as you go you should be pretty safe. If you do get a run just wait till it dries and take care of it when you do the next sanding pass. Conversely don't let your rag get too dry as you apply the poly, regularly "rejuvinate" your rag with more poly as you go. You'll feel it if the rag starts to dry too much as it will feel like it's dragging on the surface as you go, and the finish will start to look streaky when held up in glancing light.

Satin poly is more forgiving in application and appearance than the gloss, but you can always steel wool the gloss to take it back to a satin appearance if you like. The satin poly also tends to build up to a semi-gloss look once you get above about 8 coats, so depending on the look you're aiming for you may need to re-introduce a bit of satin by buffing with steel wool again.

[rhoads56]

$300 is a bargain for the time, effort and materials. Im not sure how it is chipping during assembly, that has never happened to me. Re-drill all your holes if that is where the problems are.

[ScottR]

Wipe on poly has witness lines. I personally like nitro. High gloss and easy to repair. For 300 bucks you can get a low end compressor and gun that will do a much better job than wipe on. Even if you like poly better, sprayin gwill give you a nicer finish with less work.

SR

[Ripthorn]

I have been using EM6000 (waterbased lacquer) and have been rather pleased with it. Complete burn-in, so no witness lines. I've done one or two instruments in wipe-on poly and am not much of a fan of it. Then again, with all the effort put into a spray job, $300 really is not all that bad. But as Scott said, you could get your own setup for about that price that will finish many a guitar, but then you have to put in the time and effort, along with all the consumables (sandpaper,polish, etc.) and you are on the hook for those times when you inevitably will sand through the finish (I still occasionally do that, and always kick myself afterwards, certain that it will never happen again).

[Prostheta]

Like ScottR says, for about the price of one spray job you could maybe cover equipment to do it yourself including a temporary spraying booth made of sheet plastic and cheap (but safe!) respirator. For the price of two you can get much better gear and more than reasonable semi-permanent booth setup. Investment will pay off in the long run and is worth considering.

I feel like a broken record when I bring up the cost of time. A hand-applied finish is great in terms of not needing anywhere other than a clean reasonably ventilated area but timewise it'll rack up. Spending time on hand-rubbed finishes will intrude on your other profitable works. Best buying someone else's time (premises and insurance too) to free up your own. Each hand-rubbed job will leave you in the same position you are now, waiting to invest in a spray setup.

Oh, and a Mirka CEROS.

[madhattr88]

Tons of great info!! Thanks guys. Do u use minwax wipe on ploy, or make your own mixture?

Also, how do u go about wet sanding and polishing?

[Ripthorn]

I did the minwax route myself. I grain filled, wetsanded, and polished as normal, though it didn't take quite the same shine as nitro. I was personally underwhelmed and won't be doing one again unless it is something like for my kids.

[killemall8]

The thing i hate most about nitro is its cure time. It takes so dang long to dry, for it to end up not even being that durable of a finish.

I have some EM7000 WB lacquer that i want to try. It says it only takes a week to fully cure.

[madhattr88]

Think I can shoot poly thru my preval sprayer instead of wiping it on? Would this be a better route??

[verhoevenc]

I'm also at my wit's end with Nitro. My friend (acoustics) has fewer issues... but when you start having a lot of holes, complexity or surface, etc. like electrics do... I find issues arise. Most notablly separation around tuners (less so with push fit bushings on acoustic style tuners) and cracks around holes (electrics have more of them).

Chris

[rhoads56]

When you say cracks around holes, are these from inserting screws? Or from the buffing process?

I can honestly say these things have never been an issue for me. Is it a difference in technique, or products?

[demonx]

All I got from the whole post was blah blah blah $300

Thats a ****ing bargain! Last resprays I did I quoted $500ea for and the customer jumped at it. When I was doing all the work I was pissed off at myself that I charged so little for all the work involved.

I usually turn down spray work as it's simply a pain in the arse and people usually aren't willing to pay for the time involved.

To answer your question though, I've never wiped on a polyurethane finish, I have always sprayed, so I cannot offer advice. I have wiped on epoxies, however I would not leave that as a top coat, I believe its best to spray a clear over the top.

[Prostheta]

Calm down and get the coffee machine on before hammering the keyboard there, Allan!

I guess it is what it is. That costing should be passed onto the client or it hits madhattr88's bottom line. A $200 additional line cost (or raised anyway) deserves thought. I would be somewhat reticent to equate a hand-rubbed finish to one that is sprayed however. In my view the former should be charged at a higher rate which sort of defeats the point of the question. Sorry this doesn't help.

[demonx]

Calm down and get the coffee machine on before hammering the keyboard there, Allan!

My opening comment was a poor attempt at humour, not a personal attack as you might have read it!

[rhoads56]

Mr Searl, $500 is too cheap. I haven't done a respray in the last 12 months under $950 for bodies, and $250 for necks.

But, our economy can handle those sort of prices.

[demonx]

I agree with the too cheap. I don't normally take on this sort if work, it was for a guy who's a return retail customer on other items and I threw him a bone but regretted it later. In the future I plan on simply refusing all respray work.

[rhoads56]

Yeah, thats why I raised prices to what I have. Didn't stop anyone though. I just need to learn to say no.

[curtisa]

My personal situation is not so much that I couldn't afford a basic spray setup, but rather given my current rate of building I can more justify a simpler hands-on approach. Since my workflow is still a case of "do what I can when I can, or when I feel like it" wipe-on poly makes a pretty good alternative for me. The other factor in my chosing to forego a spray setup is my workspace simply doesn't lend itself well to a spray gun - I would have to be spraying outside, and would thus have to be battling the elements for most of the year to get anything finished.

I can see that if you were in the business of turning around instruments quickly and consistently a spray setup is the way to go.

[Prostheta]

Indeed. If the additional hours saved using a dedicated setup could be invested in other profitable works then it is a business decision rather than one of preference.

[madhattr88]

Seems like every builder has their own finishing opinions. Which is a good thing. Makes us all more interesting. I just want to do everything myself and not rely on others for finishing. And the best way for me to get a gloss body is with poly. Whether wipe on or sprayed.

[Prostheta]

Although it can be perceived as the "amateur approach" I have had fantastic results with 2k in a can. There is a caveat however - the premixed 2k poly is just far too solvent heavy. Not sure if this kind of product is available where you are, but I have bought rattlecans of 2k poly in the UK where the hardener is in a separate compartment to the solids and solvent which is "activated" by pressing an insert from the cap into the bottom of the can to marry both components. That technically dried to the touch within half an hour or so and is fully cured within a day or two. Amazing stuff. Three cans clears an entire instrument however I guess you need to time your successive coats to ensure each layer chemically bonds to the last rather than mechanically to reduce the occurrence of any witness lines.

These cans run a bit pricey but can produce a durable amazing finish compared to the run of the mill premix rattlecans. You might want to look into these and perhaps do a test. I know this isn't directly answering the wipe-on poly topic however it is a good one for the time-impaired if you have a clean area to do this kind of work.

[HuntinDoug]

I have a local guy I started using a while back. His name is Alexander Williamson. He is a luthier, but his shop is set of specifically for professional guitar finishing. His prices are very reasonable, and his quality is good enough that an un-named, well known northern KY custom shop uses him exclusively. They actually brought him in for a few months to train him on their procedures. Now they farm out all the finishing to him. I think he uses Simtech Poly.

Here's his Facebook- https://www.facebook.com/WilliamsonWorks

[killemall8]

Wow, almost a grand for a respray of just a body. I cant believe people actually pay for that. You can buy most whole new guitars for that price. I wouldnt want to charge that much even if somebody was willing to pay it. Seems insanely overpriced to me. Bu they, if they pay it.