Finish Problem

[dabeeler]

I recently made a pencil and pen finishing with CA over shellac. I applied the shellac, made from dewaxed flakes and about a 2lb cut or so cut, and brought up a high gloss polish by adding a drop of BLO to the shellac which was then applied with the blank spinning in the lathe. The friction brought up a very deep high gloss shine that felt very smooth and got very hot as it does when applying CA/BLO. I then applied four coats of CA (medium) and BLO to create a durable top coat. This was taken from the lathe to the Beal Buffer and processed with Tripolee, White Diamond and Ren Wax, the result of which really looked good. One blank was Bubinga and the other Purpleheart.

Now the problem. I have been using the Bubinga pencil and almost immediately it began to show dull spots under the finish on the lower barrel which have grown in size and are very noticeable. These dull areas appear to be under the CA finish. The Purpleheart pen which has not been used has not developed any dull spots as of yet. Both were done last weekend.

Any theories on what is happening here?

David

 

[workinforwood]

Shellac sticks to just about anything and can go under or over pretty much anything, so I have no clue what the problem is with the CA finish. Did you rough up the shellac a bit before applying the CA? Maybe the CA isn't sticking and what you are seeing is a layer of air or moisture inbetween the two products.

 

[DCBluesman]

My educated guess is that your Tripoli buff went through the CA in places. As soon as the undercoat (shellac) began to be exposed to the oils from your hand and the natural dirt and chemicals in the environment, it dulled. Tripoli on a buffing wheel is very abrasive.

 

[NewLondon88]

My guess is that although you got a nice looking finish on the shellac, it was dry to the
touch but not cured. The alcohol that is still in the shellac can act as a solvent on both
the shellac and the glue.
Again, just a guess. I'm no expert on either one.

 

[jttheclockman]

A few things here. Why did you use the shellac??? Using a thin coat of CA would have sealed the wood just fine. If you wanted a bit of color the blo would have done that. You are mixing too many variables in a finish and unless they are the same brand such as dyes and stains and things like you would use on flat work it is a bad idea. You have to remember when using a mixture of blo and CA you are doing 2 things and am no scientist so I can not prove it but it would make sense, you change the chemical makeup of the CA and also you are thinning it. So this means more coats in my opinion.

Anything could have happened. The blo mixing with the shellac may not have dried properly before you put the CA and blo on. The CA/blo may not have dried properly before you went and buffed. Like someone else said you may have buffed the coats of CA off because like I said you need to step up the amount of coats if using CA/blo. You maybe getting off gassing due to the wood type under the finish.

Now there maybe a silver lining, it may disapear when dries or settles down. Give it a couple days and see what happens. Do not put it in sunlight. This is only my opinion and you get what you paid for it.

 

[leehljp]

I agree with Lou on this.

I used to get that often and finally learned that when I see a "flat spot" it is because there is not enough CA there to hold the shine. Of course it was shining when I took it off of the lathe, but that didn't mean that there is CA there.

CA thickness/application is VERY subjective. The vast majority of CA "flat spots" is due to sanding through or buffing through and leaving only the wax be the 'shine', which later wears off.