My first full build from scratch

[birch]

16 minutes ago, ScottR said:

I have used the Tru-oil slurry method of grain filling with shellac and found it to be very effective that way as well. it basically substitutes shellac and wood dust for the pumice that Prostheta's method describes. And Andy, I've found that lacquer sticks to Tru-oil like a champ.

SR

I'm not sure I understand. So you use the same method but sand through the wet shellac instead of tru oil and let the wood dust fill the pores? 

Edited April 11, 2016 by birch
Clarity

[ScottR]

Yes. The first couple of applications included wood dust in the slurry and after that I used shellac and alcohol as a lubricant.....actually you could say I applied the next coat of shellac with fine sandpaper and added a bit of alcohol if it thickened up before I finished the coat. This leveled the previous coat (mostly) and created a pore filling slurry. It went pretty quickly because shellac sets up quickly. When the pores were sufficiently filled I let it set up a couple of hours and did a final leveling by dry sanding and hung it up overnight and started shooting lacquer the next day.

SR

[birch]

20 hours ago, Prostheta said:

You'd probably have more success with Timbermate, however colour is the issue since there are many to work with here. A sealer of shellac (optional) fill with Timbermate and shooting your clear is an easy win. See how that French polishing video strikes you; if it's not your thing (it's an acquired taste) then go the more "standard" route I guess.

Oh so many options...

I'd like to try the method in the video if I can find a place to buy pumice. Denatured alcohol for the shellac is quite hard to obtain in Canada. The closest I could get was isopropyl of unknown purity so I'm testing that with the shellac right now.

I have some clear wood filler but it's waterbased and I'm never sure about compatibility of using different base materials together. I'm going to have to do some testing. 

[birch]

4 minutes ago, ScottR said:

Yes. The first couple of applications included wood dust in the slurry and after that I used shellac and alcohol as a lubricant.....actually you could say I applied the next coat of shellac with fine sandpaper and added a bit of alcohol if it thickened up before I finished the coat. This leveled the previous coat (mostly) and created a pore filling slurry. It went pretty quickly because shellac sets up quickly. When the pores were sufficiently filled I let it set up a couple of hours and did a final leveling by dry sanding and hung it up overnight and started shooting lacquer the next day.

SR

Ah I see. So are you talking 400 grit sandpaper, or finer?

[Prostheta]

Interesting use of shellac with Tru-oil. You're a mine of wonders, Scott.

[ScottR]

7 hours ago, birch said:

Ah I see. So are you talking 400 grit sandpaper, or finer?

400 is what I used, with a little 600 at the end.

SR

[ScottR]

6 hours ago, Prostheta said:

Interesting use of shellac with Tru-oil. You're a mine of wonders, Scott.

Actually Carl, I used shellac like Tru-oil....I haven't tried it with Tru-oil. That is a concept worth exploring though for sure.

SR

[Prostheta]

I guess that thinner cuts (1lb to 1-1/2lb?) stay mobile and workable due to there being more alcohol and less shellac sticking things up. This is more or less what I have mixed right now (1-1/2lb) for the test pieces on the bench. Sandpaper would be really prone to corning up, wouldn't it? I mean, this is entirely why French polishers use dust raised by pumice in combination with the shellac applied from the rubber. The rubber stays moist from its internal shellac/alcohol reservoir and oiled sole. Same process in essence, minus the pumice in the fill matrix. Either you'll go through a lot of sandpaper doing this as it loads with shellac or I'm missing something in my perception of what you're doing....

[ScottR]

Sand paper did corn up used dry. There was very little leveling to do that way though. Shellac is not very happy to have water on it so that was out. I considered mineral spirits as a wet sanding agent, but I didn't want any contaminants on the surface that I was going to spray with lacquer. I kept a bristle brush handy and after lightly sanding an area, I'd run the paper over the bristles, wipe the dust off the part, wipe the paper on my jeans and repeat. It's not as cumbersome as it sounds.

SR

[Prostheta]

Well, I tend to use Olive oil or Linseed as my lubricant for rubbing shellac. I think spiriting off your shellac is kind of a decontamination stage also. Not so sure about how to fully remove this before shooting anything over the top to be fair. The oil tends to sweat out so I can understand your issue. When I'm using shellac purely as a sealer I don't use a rubber, so oil is sort of a non-issue. Hmm. You've got me thinking now. That's not good.

[birch]

Having never used shellac before, I gather that it has a short working time. Is there a way to extend the working time or is it long enough for this if you work quickly?

Also I believe shellac dissolves into the previous coat so do you need to leave a coat to cure for any amount of time before starting another coat or are you just working it continuously until you're done?

[2.5itim]

I have only used shellac on scrap pieces but I didn't notice it to be super fast acting, to my knowledge it doesn't "burn in" to the existing finish. 

I believe you are thinking of nitro, it is super fast acting and does burn in. 

Im sorry if I'm wrong but I don't think that I am. 

Edited April 12, 2016 by 2.5itim

[ScottR]

It's long enough if you work quickly. I've always treated it like lacquer, when using it as a finish. Three coats a day. When I used it as a grain filler, I just went till I was done. I will be interested to see what Prostheta says about how much - if any- curing time is required.

SR

[curtisa]

5 hours ago, Prostheta said:

Well, I tend to use Olive oil or Linseed as my lubricant for rubbing shellac.

The one time I did a French polish I found I got better results using paraffin oil as the lubricating agent. Olive oil worked OK, but the finish build seemed easier to achieve evenly by switching to paraffin.

[Prostheta]

Shellac doesn't "cure" as such. It's dissolved in an evaporative solvent, in this case alcohol. Shellac can be dissolved with more solvent after application, exactly the same as nitro can be. Layers do burn into each other, yes.

Drying time is dependent on the thickness of the layer and percentage of solvent, the "cut". These can be anything from 1/2lb to 3lb cuts, which are measured in weight of shellac per gallon of alcohol.

Thin layers flash off almost instantly whilst thicker or painted ones easily take an hour or more. To dry thoroughly takes longer if several coats have been applied as the solvents migrate up and out slower with thicker applications. This is why my sample pieces in the Rick thread have roped; I applied too many too quickly in too few sessions.

Most similar oils are good for the lubricant. Olive and Linseed are just examples. As long as they don't cure before spiriting off, they're good. Never tried paraffin since food-safe ones are nicer to my life. 

[birch]

Mixed results using shellac as a grain filler... It worked very well on my flat test piece but when I tried on the curvy top, I didn't get very good results so I left the last coat alone. I'm going to keep working on the technique... 

 

[birch]

A couple more because the sunlight makes it glow 

[Prostheta]

Phew....I spent most of the morning chasing dust bunnies out from under the desk and re-routing cables around my aging and already-ancient desktop computer. Sorry I didn't pick this up last night, but we got home at 2:30am after babysitting our little nephew.

Okay, so shellac as a sealer or grain filler. It depends on the wood. Shellac can have a high surface tension (better way to describe "thickness") depending on how it is cut with alcohol. A 3lb cut is pretty substantial for example. It still sinks into the grain though, as the evaporating solvent makes it lose mass and shrink marginally. Shellac in this instance is best used to bind a matrix of wood dust raised from paper sanding (as per @ScottR's techniques) or by using pumice, which creates a pumice/wood dust fill. On its own it will seal the grain on first application, but not fill it immediately. It just doesn't have the body to do so on very absorbent and open-grained woods.

Last time I grain-filled with straight shellac was on Alder. Generally it doesn't need it, so it was more of a sealant than anything else. Still, all hardwood transports water and sugars through itself, so there's always a degree of grain porosity. Shellac is a great substrate for further finishing too.

How did you apply the shellac? I've never had good results by brushing it on, and have always used the wadded rubber applicator for a French polished application. Immensely slow but can be an amazing finish on its own. I've decided to do this with my ongoing bass project rather than shooting clear over the shellac base. If you don't spend a lot of time with French polished pieces, you forget just how slinky and deep they can be.

A rule of thumb with most types of finish application is to concentrate on getting the edges and details done perfectly first. The flat areas always look after themselves. Looking at your design, I would have started with the perimeter, f-hole, areas surrounding the pickup, rear cavity and neck pocket. Anything that has an edge or small surface area. The big flat areas are the hole straight.

[birch]

I did a first seal coat with Bullseye spray, using the spray to make sure I covered all areas. Following that, I had a 1 lb cut I mixed from flakes that I brushed and sanded starting on the upper bout around and including the f-hole. I didn't get much working time before it started to rope so I let it dry a while and flattened out the roped area before I tried it again. I got the same result the next time so I abandoned the process before I made too much of a mess and sprayed a last coat. 

It is noticeable that the grain is smoother where I sanded than the surrounding areas so I think the technique works. I think maybe I'm going too slow or applying too much shellac in an area at a time.

I tried the same process on a flat test piece and the results were great. I should have tried a curvy test piece first.

[Prostheta]

I have zero experience of pre-mixed shellac other than a bit of anecdotal info. One is that it isn't all dewaxed blonde shellac. This can be a problem when applying something else over the top of it. IIRC, Zinsser does dewaxed in tins in addition to the "stronger" waxier version. Second is shelf life. Shellac is good for six months or so when you make it yourself. I can't comment on how much better off-the-shelf products will be, however I'd probably see if they show a production date and if not, whether the store's stock is dusty and untouched.

Shellac is always best done with baby steps. I think aerosols can lay a lot of product on in a very short amount of time. They need a good long time for the solvents to outgas and the shellac to harden. Thankfully, shellac is ridiculously easy to repair and rework.

[birch]

12 minutes ago, Prostheta said:

I have zero experience of pre-mixed shellac other than a bit of anecdotal info. One is that it isn't all dewaxed blonde shellac. This can be a problem when applying something else over the top of it. IIRC, Zinsser does dewaxed in tins in addition to the "stronger" waxier version. Second is shelf life. Shellac is good for six months or so when you make it yourself. I can't comment on how much better off-the-shelf products will be, however I'd probably see if they show a production date and if not, whether the store's stock is dusty and untouched.

Shellac is always best done with baby steps. I think aerosols can lay a lot of product on in a very short amount of time. They need a good long time for the solvents to outgas and the shellac to harden. Thankfully, shellac is ridiculously easy to repair and rework.

 

I bought some dewaxed blonde flake intending to use just that but apparently it's near impossible to find denatured alcohol in BC. I ended up using isopropyl of unknown purity which took 5 days to dissolve the shellac and still left a thin gooey layer on the bottom of the jar. I have to find some denatured alcohol before I try mixing another batch. Someone told me it is sold as stove fuel in marine supply stores. I live quite close to the coast so I will look into that next time I'm in Vancouver.

All the information i was able to find about Zinsser shellac was also anecdotal so it is something of an unknown commodity to me. The can says it can be topcoated with any clear so I'm guessing it's dewaxed...

Edited April 17, 2016 by birch

[Prostheta]

Isopropyl works however it's just not perfect for French polishing on its own. For making a shellac sealer it'll work. The thin gooey layer is normal. You need to shake it every hour when you mix it up until it dissolves. My current batch created a thick layer like yours, so I have to spent twenty minutes shaking it over a couple of days to dislodge and get it dissolving again. Methylated spirits is another common name if that helps. Same thing in essence.

That's the thing about commercial products though isn't it? I mean, there's so much conflicting anecdotal info out there that you can only suck it and see before you know for sure. Even then, when you hit problems there are always ten different opinions on what happened, with everybody calling each other wrong in favour of their own idea. Hmm.

A quick read of threads associated with Zinsser spray shellac reveals variance from batch to batch. It's shellac after all - a natural product. Unless it's dewaxed blonde shellac, it can have a varying level of wax. No big deal for most finishes in reality. It's always the failures and issues that are the loudest even when they're the minority.

All in all I think that it's good for the job. If you're going to shoot over the top of it, just lightly scuff sand it to provide a degree of mechanical keying for the clear. It helps.

[MiKro]

Well I have not been on in a long time. So hello all. BTW nice build. As far as shellac, I have worked with shellac for more than 30 years.

The Zinsser brand is good for a canned, spray commercial shellac, One thing you must consider is this, Zinssers yellow labels have wax, There White label does not. Now on to using shellac flakes. If you do not have a good source for DN alcohol Use spirits. As in grain alcohol. If you are doing french polish the best grain alcohol you can find is "Everclear" 190proof or 95% drinking alcohol, for doing french polish.   So other than that All I can add is this shellac may appear hard within a week. It is not. depending on your cut allow 7 to 10 days per coat drying time before spraying any other type of clear finish. otherwise you have a high risk of continuous gassing and movement of the shellac and your clear coat will fail maybe not today but weeks or months later. One thing about shellac is this the better % your alcohol is the less this effect has. Shellac also does not like heat, Even a Stradivarius that is 100 years old will become gummy if exposed to higher temps., it is the nature of the beast. II use shellac exclusively for sealing all types of wood, especially to avoid blotching of stains and or dyes. I also use it as my toner base when spraying as it is easy to control when at a 1/2lb or 1/4lb cut.

Well Im sure I stepped on some toes, and maybe stepped in late but that's my take on it.

Good luck with your build , look forward to seeing it when it is done.

MK 

[birch]

2 hours ago, MiKro said:

Well I have not been on in a long time. So hello all. BTW nice build. As far as shellac, I have worked with shellac for more than 30 years.

The Zinsser brand is good for a canned, spray commercial shellac, One thing you must consider is this, Zinssers yellow labels have wax, There White label does not. Now on to using shellac flakes. If you do not have a good source for DN alcohol Use spirits. As in grain alcohol. If you are doing french polish the best grain alcohol you can find is "Everclear" 190proof or 95% drinking alcohol, for doing french polish.   So other than that All I can add is this shellac may appear hard within a week. It is not. depending on your cut allow 7 to 10 days per coat drying time before spraying any other type of clear finish. otherwise you have a high risk of continuous gassing and movement of the shellac and your clear coat will fail maybe not today but weeks or months later. One thing about shellac is this the better % your alcohol is the less this effect has. Shellac also does not like heat, Even a Stradivarius that is 100 years old will become gummy if exposed to higher temps., it is the nature of the beast. II use shellac exclusively for sealing all types of wood, especially to avoid blotching of stains and or dyes. I also use it as my toner base when spraying as it is easy to control when at a 1/2lb or 1/4lb cut.

Well Im sure I stepped on some toes, and maybe stepped in late but that's my take on it.

Good luck with your build , look forward to seeing it when it is done.

MK 

Great information, I didn't know about the 7-10 day drying time in particular. 

[Prostheta]

Hi Mike! Always good hearing from you. Good detailed info on the shellac, especially as Zinsser products are something totally unavailable here. A week or so for drying? That's definitely one to watch out for. I didn't realise shellac was so prone to holding onto the solvents.

That's what 30yrs of experience does for you though. We need more of that valuable input some days.