Tuesday, February 23, 2016
Sandpaper Grits
Prop Agenda: We all know about sandpaper grit. The lower the grit, the more coarse the sandpaper is, while the higher the grit, the less material it removes (and the smoother you can make your surface). You may have noticed that sometimes the grit has a “P” preceding the number. What does that mean?
Subscribe to:
Post Comments (Atom)
4 comments:
I had no idea that’s why sandpaper is rated the way it is, nor that the “P” was a European scale. I figured that the “P” was for the in between kind of numbers while the numbers sans “P” were the basic scale – kind of like how rosco added more colors and put them in the 300s as opposed to just adding them onto the end. The author makes a good distinction that the numerical values almost never line up on the extreme ends of the scale and a person – such as myself before seeing this chart – would use the completely wrong grit if not informed otherwise. Another cool thing about this article is that the grit is determined by the particle size of what comes off the material – which is really intelligent but I honestly don’t know what to do with that information nor how they figure out that measurement in the first place.
I had no idea that sandpaper was rated like this. The fact that it goes off the size of the particle makes a lot of sense, but I had just never thought of it that way. I also didn’t know there was such a vast difference between the two measuring scales. Usually when I pick up a piece of sandpaper I just look to see if it’a about the coarseness that I want and go with that. In theatre you don't necessarily have to worry too much about all the different rates of sandpaper because you aren't doing fine woodworking and usually you're just trying to get glue or paint off a piece of wood. Comparing the two scales with the average particle size really makes me wonder what they base the number off. Why is a 600 grit or a P1200 grit called that if it doesn't relate to the value of the particle size? It’s always interesting to see the dichotomy between European and American measuring standards. Where did we split off? Why have we never standardized things? Why, of all things, is sandpaper still different?
My life has changed forever. I knew grit and P did not mean the same thing but I thought that they were the same roughness. I cannot believe that grit and P do not correlate, I kind of feel like my whole life is a lie. I rarely sharpen my chisels using wet/dry paper an usually use the stones in the architecture shop, but the one time I did I went up to 4000 but I don’t know if that was grit or P. That is something I should know if I’m using it for my chisels. That seems to be the biggest problem with them not correlating because I rarely sand anything over 220, except a finish which I might take to 400, but even then, the difference is not that intense. I don’t know where I have used P if it is in the Arch shop or our shop but from what I know, I think at Home Depot, their sandpaper is mostly all grit. I now know that in general grit is finer than P for a specific number.
There isn’t much to say about this article, but it is something good to know. The important part to know is that both scales operate in the same manner (lower number is coarser) and that the coarser grits are more similar than the higher grits. This might make more difference working in props, but working in scenery I rarely go above 180 or 220 grit. It wouldn’t make much difference to me. It would make a difference to me if someone told me to buy a particular grit of sandpaper. I imagine that if one knew they wanted a particular P grit, they would designate it. Clearly, this would matter a lot more for fine wood working, but this information would also come in handy if one were to work with a foreign painter or scenic company. In the end, however, one can always tell what sandpaper they want by the feel.
Post a Comment