# Sanding between coats (Latex paint)



## titan7 (Aug 26, 2010)

I am in the process of spraying an Andersen Sliding Door Frame (Pine). I primed it, sanded with 320. Sprayed thinned Dunn Edward Premium SP1 White. Using a Titan 3 stage HVLP. After the first coat dried I could still see some uneven spots. I put down another coat on Monday, much better coverage, but got a few dust spots right at eye level :furious:, I will need to put plastic on top of my make shift paint booth in the garage this time. So I am thinking I should hit it lightly with 400grit before spraying the final coat. As it's thinned I am putting on more coats until I get perfect coverage. Is 400 okay for adhesion or does that matter? After my first coat I could still barely see some sanding lines (thin coat), so I am thinking 400 would be best as I need to remove the dust spots. 

thanks!!


----------



## user1007 (Sep 23, 2009)

I do not know the Dunn Edwards line but assume SP1 White is a color code? And you are spraying some sheen of latex/acrylic "enamel" in satin or semi-gloss. Or am I missing something and this is an oil enamel or alkyd finish?

Note that while latex acrylics surface dry quickly, it takes them up to 30 days to actually cure. If you sand them beyond the surface skin before cured you can end up with a sandpaper clogging gooey mess. So, be gentle even with the fine grit paper. And will it cut deep enough to fix your problems anyhow?

If this is a pine door, did you seal it before you primed it? That could be causing you some problems too if you did not. Pine is soft and absorbant. Sealing it gives primers and paints on top a better chance of staying only on the surface.

Don't be too much a perfectionist chasing every dust spot. You will slip and ding the door putting a hinge pin in or Fido will scratch it letting you know he wants to be elsewhere, or the wife will kick it open with her shoe to carry the laundry basket through. Murphy's Laws are always in play!


----------



## titan7 (Aug 26, 2010)

Sorry, I left some details out. I only primed the pine with an oil based primer as water based primer tend to lift the grain and they are not very sandable. This is the same thing the pro did on the first door that got damaged, warpped (Andersen said this happens?) Strange for SoCa weather, thus they sent a replacement door. I could not get a painter out to spray just the door frame so I decided to do it myself. I just borrowed my friends HVLP spayer. The paint is a semi-gloss latex SP1 is bright white, I did sand after the 1st coat of paint very lightly with 320. I was planning on using 400 this time.

Agree, chasing perfect finish is hard. I would just leave the dust spots but I need to get better coverage on the moulding that is holding the glass in place on the inside of the frame. I have the door laying flat on 6/5 gallon paint buckets with towels on top. This is how my painter did the original door, works great for not getting sags in the paint but it's hard to spray that inside molding part. I will get it finished up tomorrow AM.


----------



## user1007 (Sep 23, 2009)

If there is a next time, remember you need to seal pine. A mix of 1:1 processed, not raw, lindseed oil and mineral spirits or paint thinner works well and is cheap. then prime and paint.

That is not your problem now though. Just keep going the way you are being careful not to over abrade the surface.


----------



## titan7 (Aug 26, 2010)

Lol, I hope there is not a next time!


----------



## titan7 (Aug 26, 2010)

Well I ended up with 4 coats, I did not thin coat three enough and had some orange peel and sputtering. Let dry 24 hrs lightly sanded and thinned the paint and shot the final coat which appears near perfect. Cut the masking tape off the glass (that was not fun). Now I am going to let it dry until Sunday when my brother can come over and help me swap out the doors. So a 3 stage HVLP will spray latex but it needs to be properly thinned. I think I will be purchasing a 4 stage Fuji for future projects.


----------

