 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
| HomeDiscussion Groups General ModelsRailroadsRocketsRadio Controlled Air ModelsHelicoptersLand ModelsWater ModelsModelGeeks.com Contact UsLink To UsSearch & Site Map |
Model Forum / General / Models / July 2006Proper way to sand plastic before painting?
Hi. I sanded some plastic parts quickly with some 600 grit sandpaper to remove a small seem. Then I washed and dried them before spraying them with Tamiya lacquer, but I noticed that where I had sanded, the paint didn't take very well, and it took some extra coats. Now I'm sanding some other parts, and I've used 600, then 1000, then 2000 with water, but it still seems to have slight velvety or matte layer that I can buff off with my finger nails. I'm guessing this "fuzz" was what caused the paint to not stick properly. What's the proper way to sand plastic before painting? Thanks, Justin. > Hi. I sanded some plastic parts quickly with some 600 grit sandpaper > to remove a small seem. Then I washed and dried them before spraying [quoted text clipped - 7 lines] > > What's the proper way to sand plastic before painting? Seems to me that you're doing it just fine. The problem may lie with the fact that you are not priming the plastic before painting. Try using a model primer or, as I do, a thin spray of cellulose car primer.  SignatureEnzo I wear the cheese. It does not wear me. >Hi. I sanded some plastic parts quickly with some 600 grit sandpaper to >remove a small seem. Then I washed and dried them before spraying them [quoted text clipped - 9 lines] > >Thanks, Justin. i use the disposable nail buffers to remove that. find a 4 way and use the shine edge. at your cosmetics counter. > Hi. I sanded some plastic parts quickly with some 600 grit sandpaper to > remove a small seem. Then I washed and dried them before spraying them > with Tamiya lacquer, but I noticed that where I had sanded, the paint > didn't take very well, and it took some extra coats. Primer. Thou must prime before painting. Not only for its paint adherance but the primer will also help to reveal flaws in the prepared surface that might require further attention with the sandpaper or filler before you lay on your topcoat(s). WmB Not just prime but one must also wash the parts, I recommend Westley's Blechewhite tire cleaner. >>Hi. I sanded some plastic parts quickly with some 600 grit sandpaper to >>remove a small seem. Then I washed and dried them before spraying them [quoted text clipped - 7 lines] > > WmB First, one basic question: WHAT are you sanding? You mention "fuzz", which is typical of sanding vinyl kits. I don't know how builders deal with that problem. Resin can also be problematic. Often the surface of resin parts is hard and smooth while the interior can be softer and appear porous. In such cases, a thin coat of superglue, sanded and polished, can re-seal the surface. If you are sanding styrene, 600 grit should be just fine - especially if you are using matte paints. Gloss and silver may require higher grits depending on your painting technique. I suspect the problem is with the "washing" step. You need to remove not just the sanding dust, but also the mold release and finger oil. Hot water and detergent (not soap) followed by a nice alcohol wipe works well. An old toothbrush, toothpicks and cropped acid brushes are very helpful in scrubbing all the debris out of the nooks and crannies. And yes, a primer coat is always an excellent idea. Find the boo-boos BEFORE you get serious. Greg Reynolds, IPMS >Hi. I sanded some plastic parts quickly with some 600 grit sandpaper to >remove a small seem. Then I washed and dried them before spraying them [quoted text clipped - 9 lines] > >Thanks, Justin. I'm sanding styrene. I used hot water with detergent, but I just wiped it. I should probably have used a toothbrush. Yeah, as others have mentioned, I will use a primer for the more important parts of the kit (the Academy 1:48th CH-53E, incase anyone was wondering). I assume a flat, light or medium gray Tamiya acyrlic is OK as a primer? Thanks, Justin. > First, one basic question: WHAT are you sanding? > [quoted text clipped - 35 lines] > > > >Thanks, Justin. > Resin can also be problematic. Often the surface of resin parts is > hard and smooth while the interior can be softer and appear porous. In > such cases, a thin coat of superglue, sanded and polished, can > re-seal the surface. Only on crappy resin kits, properly done resin is monolithic. > I suspect the problem is with the "washing" step. You need to remove > not just the sanding dust, but also the mold release and finger oil. > Hot water and detergent (not soap) followed by a nice alcohol wipe > works well. An old toothbrush, toothpicks and cropped acid brushes are > very helpful in scrubbing all the debris out of the nooks and > crannies. Detergent and alcohol do not work well enough on some of the resins now being used (Smooth-On resins in particular, usually white or grey in color). A detergent and toothbrush wash is a good idea to get particulates off the surface but you need a silicone stripper like Westley's Blechewhite tire cleaner to really get rid of the mold release. > Hi. I sanded some plastic parts quickly with some 600 grit sandpaper to > remove a small seem. Then I washed and dried them before spraying them [quoted text clipped - 9 lines] > > Thanks, Justin. I usually prime surfaces before painting. I use Krylon sandable primer. I learned to use it a number of years ago based on recommendations from this list, and use it exclusively now, though I am sure there are other primers that are good. Also, did you wash with soap and water, or just water. If you used soap, you MUST rinse thoroughly to remove any trace of soap/detergent film. |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.