Tipping with a dry brush, vs pre-dampening with thinner?

Discussion in 'Materials' started by rebar, Jul 25, 2017.

  1. rebar
    Joined: Sep 2008
    Posts: 38
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: iowa

    rebar Junior Member

    Iv been rolling and tipping rustoleum topside thinned 10% with MS and valspar hardener at 16:1 and the finish is acceptable..

    My problem is my tipping brush keeps drying out starting up high where the paint ends.. And slowly keeps drying down leaving dried paint which I don't want in the finish and is difficult to clean off.

    Has anyone had good luck pre wetting the brush with mineral spirits? Not dripping wet, but just damp enough to keep the paint from drying while painting for a long time?

    Would dampening your brush help the paint flow off as well?

    Thanks
     
  2. gonzo
    Joined: Aug 2002
    Posts: 13,929
    Likes: 481, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Wetting the brush helps. Also, it is better if you first soak it in thinners for an hour or so. That way the fibers are saturated.
     
  3. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 473, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I disagree about wetting the tip off brush. The trick with tipping off is all technique and you want a dry brush, that is used vertically or nearly so, with a light touch. You're not painting, or trying to move material around into a uniform film thickness, but just attempting to knock down the stipple left by the roller.

    Ambient temperature and the drying agent (valspar hardener) are likely causing your troubles. I'd suggest you stop using the hardener and if you need it, consider a flow promoter like Penetrol. Using a flow promoter will extend the wet edge time, which is what you really need, especially if it's being painted on a hot day. Penetrol will also let the paint "lay down" so it has time to lose the marks, before it firms up. I perform repairs in a subtropical environment, trust me, the paint needs to lay down, long before the vehicle flashes off, or you'll have marks.
     
  4. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,131
    Likes: 393, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Painting in strong sunlight is always problematic,too, so avoid that wherever possible.
     
  5. rebar
    Joined: Sep 2008
    Posts: 38
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: iowa

    rebar Junior Member

    Thanks Guys..

    I'm painting in shade and about 75 degree's. Its also about 55% humidity but the temperature and humidity rise when I open the door to get the fumes out.

    The dampened brush was just a idea because when I paint latex house paint, I always have a water spray bottle which I spray on the brush where the paint is drying close to the handle to ease clean up and it seemed to help the paint flow off the brush.

    The hardener is helping make the paint hard enough to get 3 coats on in 3 days.

    Iv got some penetrol.. But after I realized it slowed the drying, I will save it for faded plastic.
     
  6. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,131
    Likes: 393, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Presumably you are painting steel ? Certainly with any kind of brush painting, it is not a bad idea to first dampen the brush with the appropriate solvent, it also makes cleaning the brushes easier, and delays drying of paint on the brush..
     
  7. gonzo
    Joined: Aug 2002
    Posts: 13,929
    Likes: 481, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    I find that pre-soaking makes the bristles more flexible and softer. I do the same with water based paints.
     

  8. UNCIVILIZED
    Joined: Jun 2014
    Posts: 166
    Likes: 1, Points: 18, Legacy Rep: 31
    Location: Land O' the Great Lakes

    UNCIVILIZED DIY Junkyard MadScientist

    Goo to know, thanks guys!
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.