Sanded down to stain (accident)

Hello all!

First time poster, long time lurker...Any help with this would be greatly appreciated! I bought 2 unfinished end tables and 1 coffee table. My wife and I sanded them down with 220 grit, applied a pre-stain conditioner, and did 1 coat of Polyurethane on the coffee table so far. The 2 end tables have 3 coats of Poly and are coming along beautifully, and we're very happy with the results!

However, when I went to sand (with a sanding block) the coffee table for a second coat of Poly, I somehow sanded right through down to the stain and now there is a few light spots all over the table!!! It was coming along so perfect until now...Ha. Needless to say my wife isn't very happy and neither am I. I used 320 grit sandpaper....Well, I figured I just sanded to hard and vowed to go lightly on the second coat...This morning, I decided to VERY lightly sand the table by hand...

SAME THING! Right down to the stain creating more light spots! What am I doing wrong!?!?! The 2 end tables didn't have this problem at all, and in fact I actually used 220 grit on those! Not sure what's going on! Any help would be greatly appreciated!

Thanks!
Andy

 

Try wiping those light spots with a rag and paint thinner. If they disappear when wet you have nothing to worry about. If they don't disappear, report back. If you have a picture, post it.

And welcome!

 

Welcome to the forums Andy!

Generally there is no need for a grit finer than 220 when working with wood finishes.
Do the light spots blend in when you apply the next coat of poly? what type of poly are you using? would these light spots show up in a pic? http://www.doityourself.com/forum/el...-pictures.html

 

Are you leaving out a step you did in your description?
Saying your sanding, prestain, then poly.
Did you stain it after the prestain?
Unless it's a soft wood there's no need for prestaining.
Should be just doing a very light hand sanding between coats.

 

Thanks for all the replies! I took a few pictures, but for some reason I keep getting "failed to upload" error message?

Anyways, the spots didn't blend in-I also tried to go over them with some more stain but it didn't take. I kind of just took it as a loss and figured I sanded to hard, but now I keep getting more and more spots every time I sand in between coats!

It's only noticeable right now if I told you about the spots-but I can't keep getting them or at the end of the project the tables will look terrible! I am using Minwax Oil based Polyurethane (clear gloss).

Thanks!

 

Yes, sorry! I meant to say we sanded them down, applied a pre-stain conditioner, then stained with Varathane "American Walnut" stain, then did the Poly! The tables are made from Parawood aka Rubberwood, I applied the Pre-Stain just as insurance!

 

Are you sure you are sanding thru the poly? poly will turn whitish when it's sanded but wiping with paint thinner or apply another coat of poly will remove the white cast. The stain not taking likely means you didn't sand thru the poly.

 

I'm almost positive I sanded through the poly. I just don't think it took because I just barely sanded through, just very light spots, especially around edges. I just can't understand why? 320 grit is very very fine...Should I use a scrubbing pad instead? Maybe Minwax makes a cheap/thin Polyurethane?

I was hoping to do 4-5 coats of Poly, but if it keeps sanding through and making spots maybe I'll have to stop now. (Everything has 3 coats).

 

220 is what I use for between coat sanding. If you're going through the poly, I think you're being too aggressive - the goal is not to remove material but rather just to roughen the surface.

 

I've never used 320 grit on wood and it takes a bit of effort to sand thru Minwax oil base poly with 220 grit sandpaper. How much pressure are you applying while sanding? It is feasible to sand thru on the edges but just on the edge itself, mostly because of the angle which sands easier and is harder to apply a thicker coat of poly to. I've applied [both brush and spray] many gallons of MInwax oil base poly with good results.

How are you applying the poly? are you thinning it any? have you stirred and mixed up the solids that tend to settle to the bottom of the can? After sanding have you wiped it down with a rag wet with mineral spirits and looked to see if the 'light' spots are still visible?