How to Pore Fill Rosette

[scamp]

Hi All

Working on my first from scratch build ( based on Martin 000 12 fret )
It has a European spruce top and Cocobolo sides and back.
I thought I would try and make an interesting Rosette out of Cocobolo scraps and some purfling I made from veneer.
It came out cool ( see below ) but now I am wondering if the Cocobolo will be a problem when I try and finish the guitar.
I need to be very careful on not staining the spruce with the oils from the Cocobolo.
Also.. I would assume I need to pore fill the Cocobolo rosette but not sure how best to do it without staining the spruce.

Any suggestions???

[Stray Feathers]

That's a one-of-a-kind rosette - nicely done! Many (most?) pore fillers will suggest you seal with unwaxed shellac or vinyl sealer before you pore fill, and that should seal the cocobolo and help prevent staining the spruce. It has worked for me so far. A clear filler like AquaCoat would also be more forgiving if you do get it on the spruce. Bruce W.

[Srick]

GluBoost fill and finish, a flexible CA worked very well on my recent first build. And definitely, seal with shellac.

[scamp]

GluBoost fill and finish, a flexible CA worked very well on my recent first build. And definitely, seal with shellac.

Thanks. Which GluBoost fill and finish product did you use? There seems to be a “ regular “ one and a “thin” one. Also seems like this is some kind of CA glue so I assume you need to be careful and probably seal the spruce around the rosette. I also assume you don’t use the accelerator that’s available.

[Kevin Sjostrand]

My first question is what are you going to use finish the guitar?

I'm many cases you can put shellac as a sealer under a finish, such as lacquer. My experience with cocobolo is the pores are not large or deep so if you have "dewaxed" shellac, brush or carefully wipe on 2 or 3 coats os shellac and then sand it back flat. Even better is to rub fine cocobolo sawdust into the pores with a munica with the shellac. When I French polish I do this and I still do it to pore fill all my mahogany and Spanish cedar necks.

Easy, quick. Just don't over sand and remove the fill from the pores.

If you don't have shellac, float some thin CA onto the coco
Let dry...no accelerator, and scrap it down flush.
I just did that a couple days ago with this abalone rosette.

[scamp]

I plan on using True Oil for a finish so a shellac sealer is definitely an option. Good to hear that the Cocobolo can be potentially pore filled this way. I also like the idea of using some Cocobolo dust with the shellac. I used this technique before to a pore fill a mahogany neck end grain. Worked well. My only concern with this is the Cocobolo in the rosette has some light colored wood. Not sure how a dark cocobolo dust would fill the pores and not stand out. I may try some experiments.

Thanks again.

[Kevin Sjostrand]

I built this coco guitar in 2010. I don't remember for sure but I believe I did the pore fill using shellac and sawdust.

See the sides. I don't recall an issue with darkening the lighter grain but I recall the back center area was sapwood and there was some affect on that from the filling.

Maybe just use shellac???

[Srick]

GluBoost fill and finish, a flexible CA worked very well on my recent first build. And definitely, seal with shellac.

Thanks. Which GluBoost fill and finish product did you use? There seems to be a “ regular “ one and a “thin” one. Also seems like this is some kind of CA glue so I assume you need to be careful and probably seal the spruce around the rosette. I also assume you don’t use the accelerator that’s available.

I found the GluBoost very forgiving and it did not give me any problems with the spruce. Manufacturer’s recommendations are to spray the accelerator before and after. It’s a gentler accelerator than others I have used and it provides just enough working time.

I used both the regular and the thin*; I had to use several coats to get into all of the nooks around the rosette and binding. Scraping the surface is a bit more demanding as compared with traditional fillers and you need a good light source to evaluate your progress. GB also has tinting powder which I used on the neck.

I also liked GluBoost’s lack of shrinkage after setting. Considering that this was my first time using the product and the excellent result that I obtained tells me that the product is not very technique sensitive and is predictable. In comparison, Aquacoat was easy to use, but the slight shrinkage threw me off.

* the regular filled in bigger gaps, the thin flowed better into smaller gaps.
** also, the GluBoost works a lot differently than your usual CA. It is truly flexible, and less prone to chipping

[scamp]

Did a deep dive into possibly using Gluboost fill product on a rosette for pore filling and found some interesting info I thought would be good to share. According to the technical support person at Gluboost you need to be careful about doing this. According to them, there is the possibility the Gluboost could stain the spruce top. They have done extensive experiments and it appears any CA type glue ( which Gluboost is ) interacts with acids in the spruce which can cause staining. What is interesting is some spruce has the acid and some doesn’t. Even pieces from the same tree might have acid and others not. It also appears Sitka spruce is particularly bad vs other spruces such as European etc. So… they highly recommend testing on a sample of the spruce you are using.

Also, they say sealing with shellac may not be good enough to prevent staining on some spruce. Again they recommend testing a sample to be safe.

Hope this was helpful to someone.

[phavriluk]

MY OPINION (and it's only one person's opinion) is to not use any cyanoacrilates without being thoroughly familiar with them, and OJT on a new guitar ain't my choice of a place to develop familiarity. The stuff is irreversible and unforgiving. The best I can suggest is that it would be lots safer to fill, scrape, and recoat with shellac until the rosette is filled and leveled to satisfaction. CA's are good stuff for folks to use while on the clock, but I ain't and I can take the time to proceed carefully. The end result is no better with CA than shellac, just faster, and with speed comes risk.