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  1. #1
    Join Date
    Jan 2010
    Posts
    78

    Default Repairing scratch in countertop

    Hi, I have a property that has what I believe to be a solid surface/corian type countertop. It just got about a 1 foot scratch in it. The color of the countertop is a dark green/mottled type color. The fine scratch shows as being very light/white (it really sticks out). My question is...how do I confirm if this is a solid surface material or not? I would think that the scratch would "blend" more if the color ran throughout. I do have a cutting board made from the same material that I could do some light experimenting with. If it is solid surface, should the scratch just buff out? I was just going to find a permanent marker that is similar in color and cover the scratch with this. Thanks for any advice.

  2. #2
    Join Date
    Nov 2007
    Posts
    980

    Default Re: Repairing scratch in countertop

    if it solid surface the color will go all the way through. solid surface countertops are basically a dense plastic. they can be sanded out with a good quality orbital sander making sure you keep the sander flat on the counter top and moving don't keep it in one place or apply uneven pressure as this will make a valley in the top. you sand solid surface using micron paper

  3. #3
    Join Date
    Jun 2011
    Posts
    208

    Default Re: Repairing scratch in countertop

    Well, you've come to the right place.

    Do NOT try to colour that scratch with a felt marker. Doing that will make eliminating that scratch much harder.

    The plastic your Corian counter top is made of is called "polymethyl methacrylate" and it's the same plastic that Plexiglas is made of. In fact, polymethyl methacrylate is used to make quality latex paint resins, clear and non-yellowing floor "waxes", acrylic grout and masonary sealers as well as acrylic finger nail polish for the ladies.

    Rather than try to sand or buff that scratch out, you're likely to have more success simply filling in the scratch with the same plastic. Go to any drug store and buy some CLEAR acrylic nail polish or nail polish gloss coat.

    I'd put masking tape on each side of the scratch, apply the clear nail polish to the scratch, spread the nail polish so that it's uniform along the scratch's length, and then pull the masking tape off. You'll have a much easier time polishing the thin bit of polymethyl methacrylate down to the counter's surface than removing all of the polymethyl methacrylate to the depth of the scratch.

    Why is the scratch white?

    That's cuz of something called "Fresnel's Law" which says that the fraction of the incident light reflected off of an interface is equal to:

    the difference in the refractive indices across the interface

    divided by

    the sum of the refractive indices across the interface,

    all squared.

    http://en.wikipedia.org/wiki/Fresnel_equations.

    (Look at the 2nd last equation on that page. The n's represent the refractive indices on each side of the interface.)

    As long as you have a scratch in a solid material, then the refractive index of the solid is going to be large compared to that of air, and so MUCH of the incident light will reflect off the rough surface of the scratch.

    Light reflects and REFRACTS at the rough surface of the scratch, and the result is that incident light rays get bent in different directions (depending on it's frequency), and your eye sees that mixture of different frequencies of light coming from different places as the colour "white". So, your scratch is white simply because of the scattering of light. That is, your scratch is white for exactly the same reason that clowds, snowbanks, waterfalls and the head on a beer are all white, even though nothing inside any of these things is white in colour.

    By filling in the scratch with acrylic nail polish, Fresnel's law predicts that you will very much reduce the visibility of the scratch. That's because right now much of the incident light is reflecting off the scratch surface, thereby creating the illusion of the colour "white".

    By filling in the scratch with clear nail polish, you have exactly the same material (and hence refractive index) on both sides of the scratched surface, and therefore according to Fresnel's law, the amount of light that will reflect off that scratch surface will become zero. No light reflecting off the rough scratched surface means no production of white light.

    Instead, the same amount of light will now reflect off the solid/air surface of the clear nail polish. And, since that surface is going to be much smoother, it should blend in much better with the surrounding Corian surface. And, if you're not happy with it the way it is, I'd start investigating how to buff the clear nail polish down.

    You'd lose little and gain much by scratching the underside of your Corian cutting board and then filling in that scratch with clear nail polish. And if it works well for you, don't thank me, thank Augustin-Jean Fresnel.
    Last edited by Nestor; 07-20-2011 at 02:05 AM.

  4. #4
    Join Date
    Nov 2007
    Posts
    980

    Default Re: Repairing scratch in countertop

    I do solid surface counter tops. sanding them is the normal process. for instance when you join two pieces together you use an epoxy that a color matched which usually is purchased through the supplier of the countertop. you want an exact color match. then when the two pieces are put together some of the epoxy puckers up from the joint. after it sets the whole area of the joint is sanded so that it all blends. you don't want to try mixing up some product recommended from wiki depend on the people who are in the trades and not on internet searches. the wrong products can damage you surface.

    sanding the scratch out with a progressively finer grit paper is all you need, if it is indeed solid surface. if you look to the underside of the counter top it should look relatively the same as the top surface in color. if it is a ssv (solid surface vaneer) it will have press board on the bottom or plywood. if it is a ssv it still can be sanded but the vaneer is only about an 1/8 inch thick.

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