toddler68 Posted January 25, 2005 Report Share Posted January 25, 2005 I brushed on about 4 coats of clear urethane (General Finishes Urethane Oil from Woodcraft, to be exact) and started knocking down the dust nibs and drips with some 400 grit wet. Now I've got this weird gloss/matte pattern like a topographical map in the finish. I read Bob Flexner's finishing book which describes this phenomenon as 'sand through' but doesn't suggest any ways to fix it. Any ideas? Quote Link to comment Share on other sites More sharing options...
Blueroomstudios Posted January 26, 2005 Report Share Posted January 26, 2005 If I read you right you have a generally matte finish but with lots of little low shiny spots right. If this what you have it's not a sand through I don't think. When sanding this you need to sand until everything is matte and no shiny spots are left. If you don't think you have enough clear there to handle the sanding add a coat or two to prevent a sand through. Then sand everything to matte. Quote Link to comment Share on other sites More sharing options...
toddler68 Posted January 27, 2005 Author Report Share Posted January 27, 2005 No matter how much I sand the shiny spots, they don't go away. If anything they're getting bigger. Almost like I'm sanding off the matte layer and exposing a shiny layer underneath. I think I might try a different brand of poly. I did some searching on the site and I think I've got some options. But I will try putting on another coat and sanding again before I do anything else. I suspect that maybe I didn't level well enough between coats. If all else fails I'll just take it to a body shop, have them shoot the clear and be done with it. Quote Link to comment Share on other sites More sharing options...
erikbojerik Posted January 27, 2005 Report Share Posted January 27, 2005 Yep...you sanded through at least one of the coats. No amount of sanding will make it better, you need to add more clear coat. When you say "I brushed on 4 coats" did you let it dry between coats? If so, then you're almost guaranteed of a sand-through. If you apply polyU and allow it to dry between coats, the coats don't melt together like nitro. They lay on top of each other. What you need to do is to apply a coat, let it tack up for ~15 minutes, then apply more (repeat as needed); this way the coats will blend but won't run (I lay the body flat). I've never tried this with a brush, always rattle cans; I think the brush will leave grooves in the underlying coats using this method. With the rattle cans the coats are pretty thin. I typically use up 2-3 rattle cans of poly per body (leaving ~1/4 in the bottom of each can), and I still wish the finish was thicker (as I also tend to sand through sometimes). Quote Link to comment Share on other sites More sharing options...
toddler68 Posted January 27, 2005 Author Report Share Posted January 27, 2005 Yeah, spray is probably the way to go. What brand do you use? Quote Link to comment Share on other sites More sharing options...
erikbojerik Posted January 27, 2005 Report Share Posted January 27, 2005 Minwax Fast-Dry Polyurethane (NOT the polycrylic in the similar-looking can). Home Depot. It goes on thin...I'm seriously thinking of graduating to an air gun. Quote Link to comment Share on other sites More sharing options...
toddler68 Posted January 28, 2005 Author Report Share Posted January 28, 2005 ...I'm seriously thinking of graduating to an air gun. ← Yeah, I probably should do the same. I think I still managed to sand down to bare wood with 4 coats on it! What a wicked pisser! So I decided to experiment with something different. I cut my urethane 2:1 with boiled linseed oil and rubbed it on. It looks freakin' awesome after 1 coat and I'll try putting 4 or 5 coats on and see what it looks like after that. I just hope it's durable enough. Quote Link to comment Share on other sites More sharing options...
BJPUC Posted January 29, 2005 Report Share Posted January 29, 2005 what brand urethane did you use? Quote Link to comment Share on other sites More sharing options...
toddler68 Posted January 29, 2005 Author Report Share Posted January 29, 2005 what brand urethane did you use? ← General Finishes Arm-R-Coat Oil & Urethane Topcoat from Woodcraft. The mix I made with the above and boiled linseed oil took over 24 hours to dry to the touch. Didn't want to wait that long in between coats, so I bought some Minwax Wipe-on poly which only takes 3 hours; it is really starting to look good now. I'll try several more coats of that and then get to buffing. I also took erikbojerik's advice and got some of the Minwax Fast-dry spray. I may use that as the final topcoat or wait and try it on the next project. Quote Link to comment Share on other sites More sharing options...
BJPUC Posted January 30, 2005 Report Share Posted January 30, 2005 thanx for the info!!! will try! Quote Link to comment Share on other sites More sharing options...
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