OK so Im have trouble with getting the scratch marks off of my model. I prmered it and it still shows the scuff marks from where Ive been sanding. Ive been using from start to finish…220…320…2000. Ive tried using Mr. Surfacer 1200 with a brush but the scuff marks are still there. Is there a certain trick to this? Im lost. Thanks in advance, any help is good!
Semper Fi,
Bret
Sounds like you’re dry sanding… Always wet sand… You’ll never get rid of sand-scratches with dry sandpaper… I know they aren’t “Cool” like the high-dollar hobby stuff, but I use Testor’s sanding films, Scotch-brite pads, and Wal-Mart Primer…
ok so if I wet sand over the scuff marks starting from 220 and wrk my way to 2000, will it get rid of the scuff marks?
If they’re deep, you’ll have to fill them and start over… Try thinning your putty as well… Dunno what kind you’re using though, and it makes a difference…
nah they are not that deep
Then the question would be, “HOW are you sanding?” Are you using a block, your fingers, sanding sticks, are you going back & forth, in a circular motion, etc… The trick is to feather the edges out…
Im using sheets of sanding paper with my fingers and Im going in circular motion mostly.
I have used sanding sticks that you can find in the cosmetics dept of most drug stores. There is one type that has four different grits on it. I have used the finest (polishing) grit to successfully polish canopy glass after it has gotten scratched. I’m not sure how it would work on a painted surface, but It might be worth a try - you could try it wet too.
Chris
I agree that wet sanding it definitely the right approach. Problem is that many of the cosmetics sticks disintegrate when wet. You can get small sanding sticks at Hobby Lobby under the Steven’s label that hold up a bit better (you can get them in bulk from MicroMark) I use the mylar-backed sanding films for most of my non-NMF sanding. I use MicroMesh system for NMF work. One trick I learned from grinding telescope mirrors that works very well on models is to sand in one direction with the initial grit (NOT in circles) then when you switch to the next finer grit you sand perpendicular to the initial passes. As you work your way down keep switching orientations and don’t switch grits until all the scratches from the earlier passes are GONE. This ensures no leftover scratches and also avoids faceting of the surface.
Try getting a set of Micromesh sheets, and use them wet. Being cloth-backed, if you look after them, and wash them out each time, they’ll last for years, but make sure that you follow the instructions, and sand in straight lines, with each successive grade at 90 degrees to the preceding. You’ll find that the final grades will leave a glass-smooth finish; I’ve used them on canopies, with nary a single scratch visible, even managed, at work, to get a chrome appearance on previously corroded aluminium. It’s possible to find Micromesh on sticks, as well, up to four grades on each stick. Little-Cars, in the U.K., stocks them, so they’re readily available. If you decide to stick with ordinary paper-backed materials, try an old furniture-polishers’ trick; after going through the grades, up to the very finest, turn the paper over, and use the back. It will impart a gloss finish, and, even though it won’t get rid of any deep scratches that you’ve left, it’ll make them a lot easier to see before you start painting.
Edgar
“Ive been using from start to finish…220…320…2000”;
Does this mean you have gone straight from 320 to 2000? If you have that is your problem, you have jumped to many grades in one go & I would also say 220 & possibly 320 are to coarse to start with.
Using 2000 to finish 320 is a bit like David & Goliath, only this time Davie boy is not going to win. Unless you are boing some fancy finish like NMF, 1000 or 1200 is usually enough to get the surface correct for painting, working somewhere along the lines of 400, 600 then 1000.
Wetsanding isn’t always necessary and is hardly ever practical. What you need to do is get a set of polishing sticks and pads. The sticks will generally cover the range from 150 through 2000. The pads will get you from 2400 through 12000. It takes time, but you don’t have to hold your model under running water.
Personally, I get mine from micromark.com because they’re the only place I know that carries them.
http://www.micromark.com/SOFT-TOUCH-PAD-SET-SET-OF-6,7787.html
http://www.micromark.com/5-PIECE-FLEX-PAD-SET,7367.html
-Fred
Also lets keep in mind that the final finish dictates the final grit you need to sand to. If you’re doing a flat finish you’ll find that at 600 grit you’re already way past what is needed. 240 is more than sufficient for most situations especially if you’ve taken care to eliminate the larger scratches from previous grits. I too usually dry sand for flat finishes with the exception of the final grit. Also with wet sanding at 600 grit you can go over the painted surface with relative care and this is good for any of those little blemishes that show up if you’re air quality isn’t up to the task (dust, flakes, etc.) Just remember the final flat coat after the wet sanding or you’ll have shiny spots on the finish.
I usually sand seam lines and putty with 220 wet/dry sandpaper (dry) wrapped around a tongue depressor or popcicle stick, always sanding on a 45 degree angle to the stick,.(this insures a perfect surface shape with no bumps or waves). Then wet sand with 320 wet ,.then 400 wet,…then 600 wet, this is usually sufficient for just about any paint finish. If you are using a metalizer continue to 800 or 1000 wet. One thing is, that it is very possible that you are not getting all the scratches out when you think you have, (this happens to everybody). Also primer will help to fill the heavy scratches over the first initial rough sanding. Dave.
I always use a Flex-i-file for my fuselage and wing leading edge seams. The mylar strips of the flex-i-file conform to the curved shape of the seam and avoid those nasty flat spots you can create if you’re not careful. Also you get enough control with the Flex-i-files that you can prevent damaging to panel lines that meet the seams at right angles either along the fuselage or along the wing leading edge. You can get Flex-i-files at MicroMark.