LumberJocks

Acrylic poly over chalk paint...

  • Advertise with us

« back to Finishing forum

Forum topic by AAANDRRREW posted 12-29-2015 10:30 PM 504 views 0 times favorited 4 replies Add to Favorites Watch
View AAANDRRREW's profile

AAANDRRREW

111 posts in 634 days


12-29-2015 10:30 PM

Hello all,
I recently finally figured out a good process for applying oil based poly and getting good results (thin it, wipe on, sand/buff at the end).

Well that victory was short lived. My wife would like to chalk paint a pine entryway bench I built her. She did some research and found a poly she wanted to finish it with – it’s varathane water borne crystal clear poly, matte finish. I did some research and found you can’t really thin water based too too much. So I decided I better start practicing.

I am making a decorative plate holder as well. I painted it flat black with latex paint. I tried two methods (there are two pieces to the holder because it is not assembled yet. I tried wiping it on full strength and I tried using a foam brush. I cannot tell the difference in finish with either method yet. Anyway, I put a coat on. The wood grained raised as it cured. I hit it lightly with 220 sand paper, added another coat. Once cured, 220 again and another coat. Although the finish seems smooth (no nibs or crap in it) I cannot tell if the lines I see are the wood grain or brush marks. Also, I don’t know how I feel about the finish – I’ve never used matte poly before, nor have I used water borne much either. I have attached photos of the plate holder (yes, it’s kinda crude) with the light reflecting to see the lines. I also attached a photo of the poly she wants me to use. I am hoping someone will tell me that’s just the wood grain and as I continue to apply coats it will get smoother. Or maybe this is how it looked when you poly over paint. (Which I’ve never done before either)

So far, I’d have to say I was surprised wiping it vs foam brushing it yielded the same results, and I am pleased with how easy this stuff goes on and how quickly it dries – but I am not sure how I like the finish. I can also say, to this point, I prefer oil based poly.


4 replies so far

View David Taylor's profile

David Taylor

326 posts in 549 days


#1 posted 12-30-2015 12:35 AM

That definitely looks like wood grain to me. I don’t know if it will smooth out, though – that might take many, many coats. I would try a couple more coats and see what it does.

-- Learn Relentlessly

View AAANDRRREW's profile

AAANDRRREW

111 posts in 634 days


#2 posted 12-30-2015 12:47 AM

OK, I planned on doing a few more coats anyway – this piece is kind of the practice for the bench.

So – lets say its wood grain. Why did this happen? Did I not sand enough before paint? Did I not sand enough after my first coat of poly? (I couldn’t go too much more without biting right through the poly and paint…).
To help clarify and hopefully figure out why I got what I got, this is what I did:

1. Sanded raw wood (pine) with 120 as I always do, to what I thought was a nice smooth surface.
2. blew off saw dust then used damp rag (water) to wipe down – then dried with another rag
3. painted with two coats of flat latex paint
4. brushed said poly on with foam brush – let cure
5. sanded with 220, pretty rigorously
6. cleaned off dust w/ damp rag, dried
7. coat of poly
8. sanded as before
9. coat of poly
10. let dry, got upset, took pic, posted here :)

View Ger21's profile

Ger21

1047 posts in 2593 days


#3 posted 12-30-2015 12:36 PM

What does it look like after the latex paint, but before the poly?

If the latex finish isn’t perfect, any flaws will transfer to the final finish.

Water based poly can dry really fast, so it can be tricky to not end up with brush marks.

My preference would be to spray on the poly.

-- Gerry, http://www.thecncwoodworker.com/index.html http://www.jointcam.com

View AAANDRRREW's profile

AAANDRRREW

111 posts in 634 days


#4 posted 01-06-2016 02:06 PM

Hi,

I would say that the paint before poly had some grooves like you see above (which I think and others I have show say is wood grain). I did practice some more on some scrap and sanded after the paint dried (before poly) with 220 grit sandpaper. Seems to have helped. I’m not sure if the black paint really accents the imperfections vs a stain or is it something I’m doing wrong.

Unless someone else gives me a tip on what I’m doing wrong, I will just lightly sand the painted surface to try and get the grain knocked down some so it doesn’t show through the poly as much. Its difficult to do a good job at this though because you sand just a little bit too much and your through the paint to raw wood…

I also tried something different – I noticed that the painted wood SOAKS up the poly way more than stained wood. To the point of I load my brush up to what I think is a good amount, and before I can make a full brush stroke, its dry and I need to get more on the brush. I did try and load my brush up more than I normally would and apply. I felt like I was slathering it some, but that piece seemed to dry to a better finish. I wonder if I’m not applying enough, so the thin coat dries really quick, along with the added working as I apply more poly gives me the results I don’t like. Problem with slathering it on like this is obviously drips and runs.

Speaking of overworking the poly…. I’m a chemical engineer and when I read somewhere that over brushing causes the chemistry to screw up – I have a hard time swallowing this. It seems like the shearing force of the brush wouldn’t be enough to physically alter the chemicals… Is this overworking more of a “its drying fast and if you keep messing with it, you’re not giving it time to self level and you’ll end up with strokes?” I’d say at most I take 4 swipes at it with a 2” brush, the last one being just barely dragging it across to get the bubbles/brush marks out.

I did also try wiping on diluted and non-diluted with a rag… It went on ok and the finish was ok, but it was rougher than a brush but slightly better than a cheap foam brush. Maybe I’ll wander over to youtube to see if there are some vids of ppl applying it so I can get a better idea of how much is good and how many strokes I get before its game over.

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com