Spraying Polyacrylic...

[pslamp32]

So i've finally dialed in my HVLP to the point where I'm confident enough to use it for important projects. My question is how many coats of water-based poly do you usually spray? I'm spraying quartersawn white oak tabletops...

This is before spraying the poly.

I've sprayed about 5 coats. It looks great but since I didn't fill the grain at all there are still ridges where the grain still shows. Should I continue spraying until it all fills in and everything is level or leave it as is. I assume spraying requires more coats than brushing, am i right here?

 

[jeff...]

If you didn't stain the wood, sand it with fine sand paper in between coats till the finish is built up enough. The cool thing about polycrylic is it does not dissolve or soften itself after dry with a wet coat, like some finishes do, so it's easy to build up. Several mist coats should do the trick...

If you stained the wood you'll have light spots where the grain is high and the wood is uneven which will be exposed by sanding - that's one red looking piece of white oak? Is it just the lighting or is it cherry stained?

Thanks

 

[pslamp32]

Yes it is dyed with transtint.

 

[skysharks]

Depending on how thick each coat is, but like Jeff said light coats with sanding between. My experience usually about 7 coats and the ridges should about disapear.
I know at first it looks like man are they ever going away, then bam it happens.

Yes I Said "bam":rotflm:

 

[DaveO]

If you are trying to fill the grain with top coat finish you will need to apply several coats and then take a sanding block (with a broad flat surface) and remove the finish from the high spots leaving it only in the low spots. Like Jeff mentioned be careful of cutting through the dye on the high spots. A top coat finish is going to lie on the wood like a blanket building up equally on the high grain and the low grain. That is why grain fillers are used first to fill the grain before a top coat is applying.
Once you've got the surface leveled, a few coats on top will give you a glass like surface. Spraying won't build a finish as fast as brushing, but you will get much better results.
Dave

 

[skysharks]

:icon_thumboth these guys are absoluetly correct.
I had to learn the hard way and ended up getting into my stained high spots.
So I would keep putting it on till the low spots where good and covered, of course sanding in between each coat.
What I wasn't picking up on, was what Dave said ,was that each layer was coming up uniformily. SO I always would end up with a nice and shiny surface but not glass/mirror smooth.:tinysmile_cry_t4:
So if you haven't used a grain filler, then you will have to use Dave's rememdy, which I have done on way too many occasions. :embaresse
cause I was in a rush.:BangHead:
And I hate sanding, but I was my own worse enemy.

Now I really do allot of prep work and try not to be in a rush:eusa_danc

 

[Travis Porter]

I haven't sprayed polycrilic, but with Target USL I only have to sand the final coat. If you want to get the top smooth, sanding between coats of clear finish is the way to go IMO. I normally spray 7 to 10 coats as it dries fast.