Finishing Extira

[jchsawdust]

I have a few outdoor signs in the planning stage and wondered on how to finish a new product called Extira. It is similar to MDF but made for outdoor use.
My plan is to spray (HVLP) the piece, where the letters and graphic will be, with a latex primer and an all surface enamal.
Machine the letters and graphic (AREA CLEAR to make everything stand out).
And finally, clear top-coat the entire piece with an outdoor polyurethane.
My concern is using both water-based (primer and enamel) and solvent-based (clear top-coat) products together. Are they compatable when used together?
Of course, if there are better solutions and ideas, please pass them along too.
Thanks,
John H.

[kerrazy]

I would not suggest the comboination of Enamel and then the poly.

A couple of things,
1. ensure no 90 degree edges, as the paint won't adhere well to those, so relieve them with sandpaper or something similar.
2.A good latex primer will work well, but after you apply it set up a good size fan to blow over the sign blank, as the substrate is supposed to be waterproof, it will not absorb moisture so the fan will aid in moving the moisture out of the primer. at least 2 - 3 coats of primer, on all surfaces, other wise it may cup or warp.
3. Then I would suggest a good quality exterior household latex acrylic paint. Enamels do not have enough elasticity in them and harden to much, where the latex acrylic remains flexible over the years and will not crack and blister as easily. It also reduces the need for a clear coat afterward as well, as it is not as effected by UV rays as enamels and or clear coats.
have a look at http://makingdust.ca/gallery.htm
to see some similar work,
Dale

[dave_draper]

I agree with Dale, and would like to add that the quality of the primer and 100% ACRYLIC LATEX are KEY to the success of this project.

Top of the line Benjamin Moore, or Dutch Boy paints, or other top name brands in the 25 year catagory are the right choices.

One other thing: the flat sheen or satin finish will look better and give you less trouble than the gloss finish. There is omething about that gloss finsih that likes to scrape off when you run your finger nails across it. I think you will find the flat or satin to be a very professional looking finish.

Lastly, for purposes of longer life, use ready mixed paint from the factory when ever possible, and this is especially true if using red paints.

We have found that blue lasts much longer, and a sign with a dark blue background with gold leaf lettering will last for years.

If using Sign Gold plotter cut lettering for the lettering, you will have to use High Performance vinyl underneath the Sign Gold. We would use black HP vinyl as an OUTLINE/SHADOW then place the Sign Gold on top of that.

Sign Gold will wick up moisture fromn the latex paint and will develop dark brown freckles, ruining the project.

Be sure to seal all the edges of Sign Gold graphics.

I think that's about it.
Sorry for writing a book this.