base coat directly over epoxy

S

sooner80

Im painting the dash from a harley fairing , already sanded down with 180 & is ready for epoxy , is it ok to apply the base coat directly over the epoxy without sanding (pain to sand all nooks ) just want to verify that I'll get proper adhesion ? The base will be applied about 1 hour after epoxy .. Does this sound acceptable .
Thanks Scott
 
I would go a little finer grit(atleast 320) on the final sand before epoxy. What color? Just my $.02

Are you going to reduce the epoxy at all?
 
Base over fresh epoxy is the best way to do it. Reduce your epoxy 1:1:1 so it is a thin "sealer" coat and it lays down texture free. Sand to atleast 320 before epoxy sealer.
 
orangejuiced86;18341 said:
I would go a little finer grit(atleast 320) on the final sand before epoxy. What color? Just my $.02

Are you going to reduce the epoxy at all?
Click to expand...

Darn, you must have beat me by seconds!
 
The dash will be HOK Black pearl over SPI black epoxy , & was thinkin that the dash need to be sanded again , so you think 320 would be good ?
Thanks Scott
 
me opinion is take it down to 500. reduce the epoxy as a sealer 1:1:1 and go from there with your base.

I've never pushed the final grit before base. I always go 500-600.
 
320 will work, but you need to make sure that you spray your sealer wet enough so it fills the scratches. Most of the time, I do my final blocking with 320 then go over it with 400 wet on a soft pad just to be sure. It is cheap insurance in my opinion. For metallics, sand to 600 before sealer.
 
I was just concerned that if I went with a finer grit say 400-600 that the epoxy wouldnt stick as well . The dash is made of fiberglass
 
OK I'm confused... I thought the epoxy needs p180 or less to get a good mech bond. Does the fiberglass have a chem bond metal doesn't that reduces the need for the 180?
 
It's harder to get adhesion to some substrates than others. Are you certain the dash is fiberglass? Some plastics require adhesion promoter, and without it there will not be adhesion regardless of the depth of the scratches.

We should be exactly sure of what you are spraying over before making recommendations.
 
My $.02 worth is that the mechanical bond provided by the anchor pattern is all about surface area. You provide more surface area and you will have more bond UNTIL your reach to the point where the bonding agent begins to bridge the anchor pattern, at which point you won't have as much surface in the bond.

Epoxy sticks far better than base or clear, so why would it not stick to 600 grit is my way of thinking. I shot SPI epoxy over 600 grit and it seemed to stick like glue.

Others may tell me I am all wet, but until then that is my way of thinking.
 
Crash has a good point (as always). In addition to what he said, I think you may be skipping a step. No matter how straight you think that glass fairing looks, it would be best in my opinion to spray a couple coats of epoxy on the parts and block sand them. If you sanded the fiberglass to 180, spray epoxy over that. Then block it with 320 to make sure you dont have any high or low spots. You might fecide to go a step finer with wet paper, then spray your last coat of epoxy 1:1:1

When I first read your post I thought primer blocking had already been done.
 
Its not the fairing , I have no problem with epoxy,prime & block on it ..This is the dash inside the fairing off an 2006 street glide the part that holds the gauges , speakers & radio etc... I could prime it after the epoxy & sand it but its already nice & smooth (sanded with 320 ) thats why I was thinking of going straight to the base after epoxy
 
I did one a few years back that was an "elcheapo" thing off ebay. it was a hand laid fiberglass piece. Needed some work to make it look nice. But he only paid $100 for the outer and inner. IMG_1256.jpg

IMG_1277.jpg

IMG_1294.jpg
 
Nice job, the one I'm workin on is new from harley & has lots more holes . I think its molded plastic so it will get adhesion promoter . I would post a pic but every time I preview just shows the red x
 
I did one last year just as Strum 456 described.... Sanded with 220 or something.... 3 coats of epoxy unreduced... sanded after a couple days to probably 320... sealed with the Epoxy mixed 1:1:1 and then the base clear
fairinghd.jpg
 
Not all plastics need adhesion promoter. If you can, carve a sliver off the backside and see if it floats in water. Be careful to knock off any air bubbles that would give a false result. "If it's a floater, it needs promoter!"
 
To check if it's a variety of ABS (needs no promoter) slice off a sliver and put it in some lacquer thinner or urethane reducer-it will turn to mush or melt in 15-30 minutes.
 
You must log in or register to reply here.
Back
Top