# Sanding polyeurethane



## 6SpeedSD (Jan 21, 2011)

I'm getting ready to seal some furniture I made with polyeurethane. I know you are supposed to sand between coats with like 220 grit. My question is can I use a 5" orbital sander or does it really need to be done by hand with a block? I've never worked with the stuff before, so I wanted to ask before I messed around and ruined my finish by doing it wrong!


----------



## cabinetman (Jul 5, 2007)

6SpeedSD said:


> I'm getting ready to seal some furniture I made with polyeurethane. I know you are supposed to sand between coats with like 220 grit. My question is can I use a 5" orbital sander or does it really need to be done by hand with a block? I've never worked with the stuff before, so I wanted to ask before I messed around and ruined my finish by doing it wrong!



The finish should be cured. If not it will get gummy. I prefer to use 320x in between coats and do it by hand. 












 









.


----------



## 6SpeedSD (Jan 21, 2011)

Cured? As in heat cured?

I'm still new at all this so I apologize if that's a dumb question!


----------



## Geoguy (Feb 22, 2008)

*Read the label and follow product instructions*

The term "cured" can be confusing when speaking of polyurethane. To fully "cure" polyurethane can take three days or more. There's no need to wait three days between coats if "lightly sanding" to promote adhesion of the next coat. The product instructions may say to wait 24-hours and "lightly sand" (meaning by hand) between coats. I have used a random orbital sander between coats but it's probably too agressive and I don't especially recommend it.


----------



## 6SpeedSD (Jan 21, 2011)

Well I've applied one coat, and it looks and feels dry to the touch. It's been about 2 hours since I put it on. It feels rough to me. I know lightly sanding will
smoothen it out, but won't the next coat do the same thing?


----------



## PaperJam (Jul 31, 2010)

I like to use 220 after my first coat to knock down any bubbles and such, then I use 1000grit automotive sandpaper from Autozone between additional coats, then 2000grit after the final coat. 

It is all VERY light sanding, just enough to make it smooth unless there are obvious runs that need fixin. 

I used to use tack cloth after sanding to remove dust but recently switched to microfiber towels with excellent results. The microfiber towels will also tell you if you need to sand more because it acts like velcro on rough surfaces.


----------



## PaperJam (Jul 31, 2010)

6SpeedSD said:


> I know lightly sanding will
> smoothen it out, but won't the next coat do the same thing?


Your coats will get progressively smoother. I would wait at least 4-6 hours before you TEST sand or you risk making a big gummy smear spot that won't easily fix.


----------



## 6SpeedSD (Jan 21, 2011)

Sounds good. I'll let it sit overnight and give it a light once over. One of my pieces had a few bubbles pop out, but the other didn't. No runs so I'm good there.


----------



## 6SpeedSD (Jan 21, 2011)

I sealed a 3rd piece late this afternoon. 24"x12"x12" toy box for my son. All made of poplar. Only applied one coat, and it turned out perfect! The table I stained was also made of poplar, but it is really rough feeling. Why would one piece dry so smooth then the other so rough? And the piece that bubbles up on me was red oak.


----------



## Mizer (Mar 11, 2010)

As others have said if it is not cured it will gum up. When it is dry it will leave a white dust. I use a wipe on poly, mainly because I think over all it is quicker than spraying, unless you are doing a whole set of cabinets or something like that. The first two coats I cut (dilute) with mineral spirits. The last two are full strength. I use a sanding sponge between coats. I like to use the fine grit which is about 180. The first two sandings/coats I am just going over it pretty quick the third I take my time a little more and try to flatten (eliminating most shinny spots. The last sanding, which leads up to the fourth coat I take my time and get it completely flat, here is where you can get rid of any remaining swirls from sanding the wood.


----------

