Wipe-On Poly Application

[rgand]

After starting to buff out the clear on my Roadhouse body, I have realized that I need to put a better clear on. I'm thinking of going with Minwax Wipe-On Poly, which a test piece tels me will work over what is there already. I know thin coats are best and just keep building.

I can't find a good video that shows anyone putting it on a whole body, much less with a stain/finish on it. The most helpful videos have been someone putting the stuff on top of a guitar with square corners, some with binding but none on all sides of a body with a 7/16" roundover.

Does anyone have experience with this?

Specifically I need to know if I should put it on the top and let that set up then flip it and put some on the back. I guess the sides would probably get done with the top, maybe.

Also, how many coats should I put on before starting to level sand it. Not just scuffing but actual wet sanding. I'm a bit concerned about sanding through the color layers which are rather thin. I'm not going to be able to touch this up if I sand through so I want to get it right first off.

Lastly, what temperatures do I need to have to get the poly to cure properly between coats? Right now, it's 48° in my garage. I sure don't want to wait until summer for this but I will if need be. I can start my next project and get that along considerably before it needs a finish. Then I could just do both.

Thanks for any suggestions on this.

 

[Cagey]

I haven't done bodies with wipe-on poly, but I've done a couple necks. If I were to do a body, I think I'd put a paddle/tongue/holder of some sort in the neck pock the way you would if you were going to spray it, then a long screw in place of the strap hanger at the rear, so you could rest it while standing up and holding it by the neck handle, shish-kebob style. Once it's all coated, then hang it.

As for number of coats, I don't remember. You don't have to put it on super-thin like you do with the polymerizing oils. In fact, as I recall, a generous wet wipe (although,  not as wet as you'd get with a brush) will result in a finer finish. If you're too thin, it has more of a tendency to streak or have a sort of turbulent finish. Also, you don't want to have to "work" it. The less wiping you do, the better off you are.

As for temperature, I don't recall what they recommend, but most finishes are happy with what is comfortable for humans. 48° might be a bit cool, but I don't think it would hurt it. Probably just slow down the cure. On the other hand, the stuff I used (Behlen's "Master Gel") didn't have an obnoxious odor or off-gas that much, so if you had to do it in the house it wouldn't be the end of the world.

 

[rgand]

Thanks, Kevin. Those are some good ideas. I hadn't thought of putting a long screw in place of the rear strap hanger. That I will do before starting with this. I'll probably do a handful of coats before attacking it with sandpaper and then only lightly.

It would probably be a good idea to do a sample to see how long it takes to set up to workable in those temps first. I may be able to rig up a place for it to dry inside, safe from dogs and cats.

One problem with working in a cold garage is it causes me to find other things to do inside.  :laughing7:

 

[Cagey]

A sample is good idea. There's sort of a trick to wiping on poly, although I couldn't describe it. You have to sorta just do it, adjusting your technique as you go to get the result you want. It's not like wiping on oil or stain, where you're literally just wiping it in as if you were cleaning a window. It's more like you're brushing it on, but with a cloth and a small amount of pressure. The same caveats apply about streaking, overworking, amount of material, etc. and since poly is tougher to work with once it's cured, you want as good a finish as you can get so only nominal attention is needed after the fact to clean it up.

 

[rgand]

I've done small samples for color or whatever but not in 48° conditions. This will be fun interesting to see how long it takes before it's ready for another coat.

It'll certainly require several cups of coffee.

 

[DarkPenguin]

What I did and then where it seems to have f'd up.

I put the dye down until I was happy.
Shellacked until it was level and filled.
Three coats of wipe on poly on the top and sides. (I had it laying flat on my table.)
Scuff sand.
Three more coats of wipe on poly.
Scuff sand.
Three more coats.
Scuff sand.
Three more.
Final sand.
Buff.
Polish.
Repeat for the back.

I had to sand off whatever poly had dripped to the back. Not a lot but then there were so many coats it built up along the edges. The net of this is that I sanded through in spots and just gave up on it.

I didn't level things with shellac on the back as evenly as I did on the front. The net of that was that I went through the poly into the shellac at spots.

The front has some odd scratches that appear to be under the surface. I presume this is an artifact of how the scuff sanding filled but these didn't happen on the back.

The sides were a nightmare but then there were oddities with the construction of this body to begin with. This is mostly a learning experience and not the final body I want to make so it's all good.

Also dust will screw you. It is a lot of coats and a lot of tiny application rags that can lint all over everything. The best coats went on when the furnace was broken.

 

[Rick]

I've done lot's of objects (doors, tables, clocks and picture frames) with wipe on polys and they come out looking great.  I always used true oil on necks and bodies, it seems little thinner, but poly should work.

Make yourself a handle as Cagey suggests.  That way you can do one coat at a time and just hang it to dry.

I never level sand it, I just scuff sand between coats.
I never wet sand.
The last coat is the last coat, no sanding, just leave it.  It will be beautiful.

As to number coats, as many as look good to you.

The secret is thin coats.

As to temperature, 48 degrees is too cold.  Bring it inside.  I wouldn't do it below 60 degrees. Plus you don't want to be bothered with dust from the garage.  I've found I can sand it down and start over, and I've never seen a blemish.

(PS do any grain filling before you start)

 

[Cagey]

Sanding sides and edges is always a problem due to some physical things that tough to feel/control.

Where the problem comes from is the distribution of pressure. When you're sanding a large, flat surface, the amount of pressure you apply is more or less evenly spread across the contact surface. So, if there are 6sq" of sanding surface, and you apply 2lbs of pressure, then you're applying .33lbs/sq" of pressure to the surface. When you get to the edge of that surface, if the sanding surface gets reduced due to overtravel/overhang, the surface area changes. When that happens, even if you're applying the same 2lbs of pressure, then the amount of pressure increases on the contact area directly proportional to decrease in contact area. So, if for example the contact area is reduced to half, the pressure doubles. With the increased pressure comes increased cutting force, and you remove more material. Around the edges, the problem is even more exaggerated, as the contact area may reduce by as much as 10 times or more, with the concurrent multiplication in pressure. So, what feels like light sanding, or even just no more aggressive that what you were doing, suddenly turns into the jaws of death, chewing finish off at a high rate of speed like a buncha Langoliers.

So, what's a mother to do? Well, forewarned is forearmed. Lighten on up the edges when sanding. They rarely need the amount of attention you give to the larger surface areas. Also, prior to sanding, be careful about finishing the edges so they don't need so much attention later. If you're getting sags/runs, you're over-applying material or it's too thin or it's setting up too slowly. One way to avoid inadvertent over-attention to the edges is, ironically, to pay extra attention to them. Shoot the edges first, so when you move to the planar areas you can ignore the edges. Keeps material buildup to a minimum, making sags/runs less likely and requiring heroic measures later to clean up.

 

[rgand]

Thanks for all your input. It looks like I'll need to heed the collective advice here. Right now, we have rain and cold so it isn't finishing weather. When I get a nicer spell, I'll jump in and start getting it done.

Meanwhile, I've started the next project to keep busy. There's a lot to do before that one will be ready for a finish. It will go slower because when I can, I'll be on the Roadhouse.

 

[Mr. Neutron]

I agree with Rick about 48 degs. being too cool to put on poly, even the thinned out wipe on stuff. It sounds like you've already made a good decision to wait until you get some warmer weather.  :icon_thumright:

Is there a chance that you can lay a coat on inside your house where it's warm, let it air for an hour, then maybe take it out to the garage? I've done almost that with both guitars and cedar or fir arrows I make for my traditional archery shooting. I would spread out old papers, towels, or leftover sheets of plastic from when we painted our house's interior. Mostly on our dining table, keeping in mind that our dining table is a home-made table designed to look like an old ranch-hand/bunkhouse kinda dining table, so it ain't a thing of beauty. I got by well enough to keep the wife off my back during these times of crafting. But my wife is pretty understanding about such things, fortunately for me.  :hello2: After I got a coat on my guitar stuff or wooden arrows, and it got to dry for half n hour or maybe more, down to the basement it would go, where the temps are easily 20 degs. less than whatever it is upstairs. Be patient, and figure on only one coat per day, if you're lucky.

FWIW, I put it on wipe on poly with my finger, wearing  green vinyl glove, kind like I do Tru-Oil. I had issues with whatever else I tried to use leaving particles in the finish......

 

[rgand]

Yeah, too cold right now to do anything of the sort in the garage. I'm sorely limited on doing it in the house with all the cat/dog fur and dust tracked in and kicked up by them (just a cat right now but she had lead feet). Perhaps I can figure something out in a back room.

Right now I'm in the process of making a work bench and then a sled to skinny down wood for the bodies. I also intend to get some kind of spray booth built for finishing but that will happen down the line, when I figure out where the heck I'll put such a thing.

I'll experiment with the rubber glove. It sounds like a good way to get the poly wiped on. Thanks for the idea.

 

[Cagey]

I saw a quickie spray booth idea article somewhere that I thought was interesting. Basically, the guy installed an explosion-proof exhaust fan on the sidewall of his garage. Then he built three wood panels roughly 3' x 4' with hinges on one long side, and attached one on either side of the fan and one across the top. When he needed a booth, he could lift the top one and fold out the two sides. Gave him a ventilated box roughly 4' on a side and 3' deep to paint in. When finished, the panels could be folded back in and the floor space regained.

Seems like a clever idea, but I wonder how clean it actually was without filtered make-up air. Seems like it would pull every airborne particle or critter in the garage (and then some) past the freshly painted part, turning it into a fuzzbeast. On the other hand, if you had a relatively clean garage and could close all the openings but one with a filter over it, maybe that would be close enough for rock 'n' roll.

 

[rgand]

I've been looking on Youtube at things similar to that. This guy has a video with some good ideas in it. His fan system is good but the ducting is way overkill. The basic paint booth is sound and not expensive looking, though. All I have to do is clear space enough for one.

 

[Cagey]

Yeah, that ducting was poorly thought out. Everything was sized wrong. I half-expected that duct work to just collapse in on itself at the same time it wasn't pulling enough in the booth to clear it. But, I guess it all worked out in the end.

 

[rgand]

It would be better to mount the fan unit directly on the booth and make the exhaust duct as big as possible to go outside. I did like the use of Coroplast sheets for the walls and doors. Allowing light in is a good idea.

I saw this video where another guy built a portable booth. There are a lot of good ideas for this. I recall seeing a Dan Erlewine video where he had one mounted directly on his garage wall.

 

[Cagey]

That portable unit is nice enough, although the design makes changing the filter unusually difficult. Something that's going to suck as much particulate as that is should have filters that are easily replaced, as they're going to load up fairly quickly.

The Erlewine design is closer to what I was thinking of for something that doesn't use up any space when not in use.

 

[rgand]

I don't remember how Erlewine had his filters but I agree with you that they need to be easily replaced.

That guy with the portable one sucked everything through the filters and back out the top of it into the room where he's working, less the particulates. I suspect he'll still be getting a good deal of solvent vapors to breathe. :toothy12:

There are certainly some good ideas in his design, too. I like the portability of it but it would end up being something that needs to be moved to get to something else in the shop (In my case, garage). There's a point of diminishing returns on the number of portable items that can be in any functional workspace and still be usable. It is a clean unit, though if the filter had better access. I'd sure hate to have to remove the whole back just to change it.

Well, I have plenty of time to think that over. I'll not be ready to build one for a while.

 

[Rob]

I haven't done it with guitars but have used the minwax wipe on poly on a lot of table tops. I would recommend an absolute minimum of 5 thin coats. After the final coat, let it totally dry (days). I would then very lightly just breath over the body with 0000 steel wool in long, smooth, easy strokes. You'll feel the smoothness. This has worked for me.
Good luck with whatever method you choose.

 

[rgand]

Thanks for the input on this, Rob. It will get at least that many. I suspect quite a few more although I'll stop when it seems right.

 

[Bob Hoover Ross]

I would recommend an absolute minimum of 5 thin coats. After the final coat, let it totally dry (days). I would then very lightly just breath over the body with 0000 steel wool in long, smooth, easy strokes. You'll feel the smoothness.

So are you *not* sanding between coats?