I’m having some troubles getting a simlpe layer of epoxy with pigment right.
A week after I did the lamination of my board I thought it would be nice to paint the bottom of the board yellow.
My idea was to do this with epoxy and add some yellow pigment.
I used a paintroller and the results looked good until I got back to see the cured layer the next morning:
It wasnt the smooth and shiny surface I saw the evening before, instead it had turned into a bumpy mess.
Anyone any ideas what might have gone wrong?
-The pigment vs epoxy mixingratio was 50 ml pigment for 500 ml epoxy, Im 200% sure I got this right;
-The epoxy surface before painting was sanded properly and I used thinner to degrease the surface;
-I used clean buckets and clean paintroller
-the guy in the store thought it might have to do something with the board becoming static because of the sanding. I seriously doubt this.
you can thin your epoxy with xylene (and other things), but you should avoid any wipe down of the clean, sanded epoxy surface before applying the next layer.
the common culprit when people get this type of issue with their epoxy coats tends to be a denatured alcohol or other solvent/thinner wipe down.
really, any sort of surface contamination left behind by greasy fingers or evaporated thinners can potentially cause issues like this where the epoxy separates and leaves dimples (orange peel, fish-eye).
a good piece of advice that I try to follow is to sand down the surface of the board and get it nice and clean prior to applying the next layer and then DO NOT TOUCH IT WITH ANYTHING.
the good thing is that you’ll make this mistake once and likely never again.
Well, I thinks thats incredible news. bad news. And close to impossible to not touch the board after sanding, but I have no choice.
Crap, I did’nt know epoxy was that sensitive…
You say any kind of solvent will possibly create this result.
What about ammonia or for example an organic degreaser?
Or is it just the fact that any solvent/liquid degreaser may cause this problem?
A few questions: What grit did you sand to? What kind of thinner did you use?
For what it’s worth it’s seems my biggest problems with fish eyes/separation occur when sanding to a high grit (400+) and when putting on a thin coat, a roller usually leaves a much thinner coat than a brush. To move the board after sanding you could use gloves to avoid getting fingerprint/oil on the sanded surface. Also some sandpaper I treated with wax, avoid those.
I don’t quite understand why washing with a thinner will create more problems, tho there seems to be empirical evidence that it does. Maybe the thinners contain small amounts of oil which is left as residue or whatever.
I’d try to sand it down a bit and try to scrub the low areas with a scotchbrite and then add another coat with a brush to save it. Then sand again…
I used 80 to get rid of the biggest bumps quickly, then moved on to 120 grid and at some points 240.
My idea was that the resin will fill up the minor scratches, which it did, but eventually I ran into this fish eye problem…
I used new disposable latex gloves for every epoxy job I did on this board so far. I even brushed my teeth and wore clean underwear. Nothing seemed to help.
I guess there is no other option than to sand it down (third time in a row) and start over.
Oh and yes, the thinner I used was the most aggressive there is available on the Dutch market. The one that even solves braincells. So its not white spirit or benzene.
I was thinking in maybe using some citric acid from the supermarket or some organic paint degreaser (Like St Marc Express, if you know that brand). I was hoping if anyone had experience with these.
New gloves, new brush, new bucket. Re-use the bucket for your next lamination. No re-used buckets for hotcoats.
If you’re sanding the lamination, just rough it up with 80 grit. That’s all. You’re not really sanding, just scratching the surface. A few passes with the soft block lengthwise, widthwise and diagonally. Literally just floating the block over the lamination to get some surface scratches. You shouldn’t be creating much dust, or your sanding too much.
Denatured alcohol wipe… twice… with clean “shop towels” each time. A shop towel is basically a roll of heavy duty paper towels sold in a big box at Home Depot. New towel with each wipe. Set the used towels aside to clean your squeegies and stuff with (using white vinegar, then rinsing them off with water). The denatured alcohol you buy should be ethanol, denatured with methanol. Both are excellent solvents, extremely volitile, and leave no residue. They are both used to clean cameras, sensors, lasers, and other extremely sensitive lenses specifically because they leave no residue. If the denatured alcohol you buy has any other additive in it, it may leave some kind of residue. The Klean-Strip brand sold at Home Depot is denatured with methanol. The MSDS sheets indicate it is 100.0% volitile - NO RESIDUE. It should be clear, and smell like alcohol, not gasoline, or anything else.
Additive F… 2cc/fl. oz. of hardener.
Flick and pull all the loose bristles out of the brush. I don’t use tape… I’m afraid the adhesive will leave a residue on the brush.
That’s all. I never have problems with orange peel, moonscapes, fisheyes, ripplemarks, fingerprints, footprints, or anything else… the occasional bug is about it. Good luck.
You guys have been very helpful. Im new to this forum and Im glad to see it works.
Regarding the orange peel, moonscapes, fisheyes, ripplemarks, fingerprints, footprints, I will do some testing first and try different methods on a piece of foam.
We don’t have Home Depot here but I’ll check some comparable products and their ingredients.
I’m no expert, but isn’t it generally frowned upon to use pigment in a hot coat? Shouldn’t pigment only be used in the lam stage? Not sure if this could be the source of the problem, but nobody has mentioned it yet. Also, not all pigments are created (formulated) equal. Some are for epoxy and some for polyester. Could his problem possibly just be the pigment itself and not the prep/process?
I handle my boards bare handed (but with very clean hands), never wipe 'em down with denatured (although I used to without problems), and never have issues with fish eyes on my fill coats using Resin Research epoxy. Usually see resin separation after the first pass with the china bristle brush, but go back over it lengthwise then crossways, then final pass lengthwise. I don't ever use a roller, so maybe there's something going on with that on your problem board?
Good point.Though I’m sure this pigment is for epoxy. They sell a polyurethane 2 components varnish too, with color or a transparent version. I guess thats what you guys call a hot coat.
I wanted to use that, but a mate told me better not to, because it’s such hazardous crap. (I trust my mates more than the shopkeeper).
He told me to use epoxy as the extra layer of ‘varnish’, sand it, polish it, etc.
According to him, dingrepair is a whole lot easier without the polyurethane crap (I’m using his words here) and less hazardous.
So thats why I did the last layer with epoxy. It is my “stand in” hot coat.
Perhaps you used the right pigment, but it has been said several times on this site by much more experienced folks than me (search threads) that pigmented hot coats are not a good idea.
A clean hot coat with epoxy needs Additive F (as greg l mentioned) and should be clear. You should take care of the color work under the hot coat either by:
pigmenting the resin during the lamination stage
painting the foam, or
painting a sanded hot-coat and applying a protective gloss coat or acrylic spray over it.
At this stage if you want color, you should probably choose option 3: sand off the bad yellow hot-coat, paint the board (search threads for proper paints/technique over a sanded hot-coat), then do a clear epoxy hot coat over the paint (don’t forget the additive F) or even just a clear acryllic spray to protect the paint if you want the board lighter.
Again, I am no expert, but I know enough that it is probably “playing with fire” to try to do a pigmented hot coat with epoxy.
Agreed… no weird thinners or solvents. No organic this or that. No citrus based stuff… Stick with DNA if you use anything at all. Some people use it, others don’t. I’ve done maybe 1 or two poly boards in the last few years. All the rest have been RR epoxy, of various formulations, and I use the same system, and get the same results, every time. Maybe it’s superstition, like a ball player who has to put on his sox a certain way, but why fix it if it aint broke?
BTW… Ace brand DNA is also ethanol with methanol. Do you have Ace Hardware stores near you?