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Finishing

Shellac polishing with pad

INGREDIENTS

bioetanoloAlcool: Denatured ethyl alcohol at 96 ° colorless distilled from agricultural products rich in carbohydrates and sugars (corn, sorghum, wheat, barley, etc..) And cellulosic biomass. Bioethanol can be used instead of ethyl alcohol denatured with the advantage of eliminating the annoying problem of the residue and the bad rosaceo odoration resulting from denaturant. Bioethanol is therefore ideal for the dilution of different types of resins (shellac, dewaxed shellac, sandracca, copal, benzoe, etc..) And to carry out any cleaning even when mixed with water, acetone, turpentine, etc..


 

gommalacca scaglieShellac

Natural shellac flakes indicated  for finishing and polishing antique furniture and wooden objects.

Or

gommalacca decerataDewaxed shellac flakes

bleached and purified from coloring matter, to meet special needs restoration or use of light woods.


 

gomma benzoe benzoinoBenzoe (benzoin resin).

The benzoe is a precious resin. In the polishing pad benzoin, added to the shellac in small percentages, gives a high gloss and improves the smoothness. The benzoe is therefore essential to get the high degree of finish.


Preparation of the stock solution 20%

1- Put 200gr. shellac flakes in a vessel 1 L.

2- Pour the alcohol up to fill the container.

3- Mix well, seal the container and shake. Leave it for about 12 hours.

schema travasoFilter the resulting solution.
Pour the solution into a clean container by filtering with a stocking (nylon) and a strainer to remove any residue.


PREPARATION OF 4 SOLUTIONS

Solution at 10%:   sol 10

Fill a recipient for ½ with the mother solution (20%) and ½ with alcohol.


 

Solution at 7,5%:   sol 7.5

Fill a recipient for ¾ with solution at 10% and ¼ with alcool.


 

Solution at 5%:     sol 5

Fill a recipient for ½  with solution at 10% and ½ with alcool.


 

Solution at2,5%:  sol 2.5

Fill a recipient for ½  with solution at  5% and ½ with alcool.


For the final Polishing you can use a solution of 2-3% of Benzoin.
The process of realization of the solution of benzoin 2-3% is the same as explained for the shellac.
Use ½ of a 5% solution to get the required percentage of 2.5%.


PAD CONSTRUCTION

For pad construction are required:

- 2 white ply cotton or linen or linen/cotton 15x15cm.

recommended to use the linen for the first coats and cotton for the latest.

- Not colored wool, it curled forms the core of the pad. To give substance to the pad you can use cotton-wool placed inside the wool. The use of only cotton is not recommended because it hardens and does not distribute properly the shellac.

- 2 jars. For charging and pad maintaining.

tampone01

- Place the first sheet at the mouth of the jar.
- Place the core inside.
- Pour the solution into the nucleus.
- Push to absorb the solution.
- Wring the pad so as to avoid excessive leakage of solution.
- Wrap with second sheet.


PAD MAINTAINING

tampone02

- The pad should be stored in a tightly closed jar.
- Pour a few millimeters of alcohol to saturate the internal environment.
- Insert a thickness so as not to touch the swab with alcohol.


THE COATING PHASES

- The sanding

Sand the wood up to the sandpaper 1500 through the various degrees. 60, 80, 120, 180, 220, 400, 600, 800, 1200, 1500.

- The wetting

rub a wet cloth on the wood so as to be thoroughly dampened. Wait for it to dry. This is to bring out all the "hairs" of the wood. Now to the touch you can feel the roughness. Remember that this step is necessary otherwise you will compromise all the work.

- The sanding

Sand the wood starting with 1500, then 2000.

Personally I also pass the 2500, the 3000 and the 5000.

- Fill the pores

pomice polvere

This step is used to fill the pores of the wood. Spread the fine pumice dust "4/0" on the table. The powder should be distributed evenly over the entire table. This can be done by putting the powder into a canvas bag and pat on the table. Once deployed, a cloth pass transversely to the fibers so as to remove the excess pumice.

Swab to wipe lightly moistened with 2.5% solution. Spread well before doing parallel trajectories to the fibers, then in a circular way, then to 8 shape (described later).

lana acciaio

Allow to dry well (even 8 hours). Sand with extra-fine steel-wool "0000". This serves to eliminate any lumps formed.

Personally I jump this step for choice. To obtain a more "look-craft" instrument I prefer not fill every pores. This involves not a perfectly polished mirror but slightly "out of focus" in the final result.


THE ROUGHING

N.B. Good habit is to perform the first coats with brush, with solution 10% or even 20%. This allows to accumulate a good layer of shellac in a short time on which then perform the next steps with the low concentration solutions of shellac and realize a good polishing.

N.B. The whole process doesn't provide for presence of any type of oil! A guitar is not a furniture piece!

Keep the pad with the thumb, index and middle fingers. With ring finger, little finger and the palm of your hand, hold the tail of the pad.
It is advisable to flatten the part that will be in contact with the wood.

Pass the swab solution at 10%.

parallelo

The first path is parallel trajectory to the grain.
This is the spread.
The ideal position is to have the reflection of light on the table. This allows you to observe the progress of the work.

Caution! Never stop the pad! Planar and take off!

One stop of the pad can create the burn. Point at which the shellac will no longer attack! It follows a return to the first step of this chapter!

THE PROCESSING

circolare

The second trajectory is circular shape. Clockwise and then counterclockwise or vice versa.

8

The third trajectory is eight shape. In all direction.

The pad will drain as you pass it.
Should be considered 2 trails left by the swab. The first is when the pad is just charged, the pass is smooth. Then we will see the trail change, instead of adding shellac seems to carry it. The resistance of the pad on the surface increases making the passing harder. Understand the end of the second wake when the pad starts to not slip more steadily. STOP!

Richarge the pad and repeat the operation.

Personally I repeat it 3 or 4 times. Because I skipped pores-filling and is necessary to repeat this procedure several times.

Place the pad in the jar as previously described.

Allow to dry as much as possible.

I usually wait 24 hours. This is "First hand". Also consider that the shellac dries in a few minutes but the complete evaporation of the alcohol will apply after a month.
Recommended to give 2 "hand" for each solution.


THE FINISHING

Before proceeding with the 7.5% solution smoothing with:

- Steel-wool 4/0.

- Sandpaper 1500. (Many first pour a few drops of water on the table. This makes smoother passage).

This operation will remove small accumulations of shellac, bringing smooth and uniform table. Now we ready for the next solution.

Pass the swab solution at 7,5%.

Is performed with the same procedures previously described.
Allow to dry as much as possible.

Before proceeding with the 5% solution smoothing with:

- Steel-wool 4/0.

- Sandpaper 1500.

Pass the swab solution at 5%.

Is performed with the same procedures previously described.
Allow to dry as much as possible.

Before proceeding with the 2,5% solution smoothing with:

- Sandpaper 1500.

Pass the swab solution at2,5%.

Is performed with the same procedures previously described.

The trajectories will be performed as previously described but with "parallel" concluding passage.

Allow to dry as much as possible.

Some people perform last step with the pad exclusively alcohol charged.


THE GLOSS POLISHING

Is performed by passing the pad charged with 2.5% Benzoe solution.

s performed with the same procedures previously described.


NOTE

- If you want to obtain a final matte finishing you will pass the steel-wool in a uniform manner.

- It is recommended to replace the pad every time you change solution.
- It is recommended to perform a new passage of 2.5% solution of shellac and benzoe 2.5% after about a month.

- All products listed in the guide are available online. In particular, I recommend a shop in the site link page.
- This guide is intended for beginners and tries to explain the different steps to make a good guitar polishing but can not replace the manual experience, it constitutes the most important element to get a good result.
- For any clarification, correction, comment or information please contact me in the site web contact area. 


Francesco Verginelli

I'll be happy to answer you!

You can contact me via my Contact Page.

fv

Francesco Verginelli
info@fvguitars.com
My address
Rome - Italy

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