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Glass finishing question

Charles in SC

Well Known Member
On the inside of my James cowl the weave of the glass fabric is standing pretty proud. To get this ready for paint should I sand it and if so how much? If I sand it much I will be removing glass fabric. If I just sand it very lightly it really only sands the high spots in the weave. If I sand and fill it will add thickness and weight. What are the pros and cons here. If I sand light and paint there will be weave showing but it will not add much weight. This is the way I am thinking is best. What say Yee?
 
I have an early SJ cowl without the sandwich core, and it is like you describe. Either sand off half a layer or be concerned about adhesion. I lightly sand blasted mine and won't worry about adhesion. The weave pattern will remain, but be painted and sealed to oils.
 
I am in the process of finishing my cowl fitting now. For the inside, I sanded pretty aggressively and mixed a slurry of flox and resin. I used old hotel card keys to spread it to make the surface pretty smooth. I know it probably added about 1/2 pound but I have a FP Catto and light battery so I have a bit of weight to give away up front.

I want the inside of the cowl to be smooth and easily cleaned. It will not be perfectly smooth, but will be easy to clean after it is primed and painted.
 
On the inside of the Vans cowl I just scuffed with red scotchbrite in a orbital sander and then epoxy primed.

Not fully smoothed but should be easy to wipe down. The scotchbrite worked better than sandpaper since it seems to get down into the "valleys" rather than simply removing the "hill tops".
 
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