from back in the late 60's we found we could use latex paints as primer and apply enamel over them.
So now here it is a few decades later and as we're trying to learn to use these latex and acrylic paints, I find some problems.
I coated a few MDO panels with an water based background.After the surface had been drying several days it still had this slightly tacky feeling to it. I opened a can of bulletin color and striped the borders. This paint is usually dry in a few hours. It's a week later and the enamel feels like it's perfect for laying leaf.
How does this stuff outgas? How do folks work with this type of unpredictable time frame? I didn't try the old hydrogen peroxide trick yet.
Posted by Bob Kaschak (Member # 3146) on :
Hi Rick,
I switched from oil based (One Shot, etc), to all latex based about 15 years ago.
As far as brands, everyone has an opinion, so I would suggest any of the name brand (more expensive) ones.
What I have learned. Not all exterior latex paints are the same. I have used some brands that smell, work, dry and feel completely differently than another latex paint with the same "properties." I have run into some paints that just don't feel dry for a while, so I avoided those.
Latex paints have different coverage ranges (300 square foot per quart (thick paint), all the way to 450 square foot per quart (a nice thickness to work with). I prefer paints in the 400-450 sq ft/qt coverage, because they flow a bit better.
I spray most of my backgrounds with a simple HVLP gun with a 2.2 mm tip. I apply 3 light coats to help it out-gas easily.
All of my borders, carved letter outlines, etc are painted full body from the can and not too thick. Most are second coated. Roller coating is two coats also.
I have had no problems of paint not drying or curing when the paint is stirred well and applied in a few light coats.
Most of my work is carved, gold leaf and it works well with that also.
Mack water based brushes and Kafka striping brushes work well with latex paints.
With the size of my signs, the amount of colors, the various layers, it would be a nightmare to do it all with oil based. The fumes, cleaning of brushes from one color to the next, the amount of thinner alone, etc, would be a pain.
As far as longevity, the latex far out lasts the old One Shot that I used to used. Don't get me wrong, if I did vehicle work and such, I would use One Shot, etc, but for dimensional signs, it's latex all the way.
[ October 08, 2018, 09:52 AM: Message edited by: Bob Kaschak ]
Posted by Dave Sherby (Member # 698) on :
I can ditto what Bob said. Now here's an observation from my own experience. I started the switch to latex back when Gary Anderson started selling his Rhino paint. When it became too much for him he sold it to an Indiana company that dropped the ball, (they were perplexed that they would need to ship the paint) so I contacted Gary and he said his Rhino line was Porter Acri Shield and that his original colors were formulated by a joint effort between him and Porter. I'll tell you, that Porter paint became my favorite latex. It flows off Mack latex quills beautifully, has very good coverage, relaxes as good as any latex I've tried but still dries quickly.
Well the last paint retailer in my area that carried Porter retired and closed his store. So I was forced to start using Sherwin Williams. Here comes the point of all this. I noticed that unlike the Porter that was completely dry to the touch within 24 hours, the Sherwin Williams was still slightly tacky several days later. One set of pole cabs I cut out of HDU was still tacky 2 weeks after painting, tacky enough that when I stacked one on the other and picked up the top cap, the bottom one stayed stuck to the top one. I asked the Sherwin Williams rep about it and he said their paint can stay slightly tacky until full cure, 30 DAYS! I think I'm going to make another effort to find a Porter dealer. So anyway, some brands may dry to the touch over night and some may stay a little sticky for a month.
Posted by Rick Sacks (Member # 379) on :
Do you guys find curing time consistent with different colors?
Posted by Bob Kaschak (Member # 3146) on :
Hi Rick,
Yes, I find that they all seen to cure and dry the same. During humid weather, they may take a little while longer, but if working indoors they should be dry feeling later that day or the next day at best.
I mostly use the highest gloss paint they offer (usually a soft gloss), as with any other type of paint, it seems to have the best longevity. If its an interior job, I lean more to the satins/flats.
Hear in the Adirondacks, its like the Pacific northwest during the fall, just cloudy, rainy, and wet with temps in the 40's-50's. Here inside the shop I try to keep the temp around 72 and the humidity around 50%. Drying seems consistent in these conditions.
