Using the RR epoxy - which, in general, I think is great stuff.
after laminating I’ve sanded all the bumps out and have it nice and smooth. The problem comes in trying to use the epoxy for a final/gloss coat. I’ve brushed it out like a regular hotcoat. And I’ve tried to squeegee it on as a very thin coat. I just want it to flow out and get and even coat to give me a nice shiny finish - which the resin dries with naturally.
My attemps so far have gone two ways - either I get build-ups on the rails that look like the resin is running off around dry spots (regardless - it seems - of how smooth it looks after brushing it out - And I have tried hard to make sure that it’s evenly brushed out), or… I get voids where the resin seems to pull away from areas leaving a low spot that shows the sanded surface. I think it may be that the resin is too viscous (I’m using the F stuff too). The surface of RR Epoxy is shiny and I’d really like to get a nice even final/gloss coat.
Any ideas as to how to get this final coat smooth and even? I’m probably missing something very basic.
My laminating is getting better, but it’s damn frustrating to not be able to get the final finish uniform.
I sanded to 150 – blew off the blank real well with air pressure – moved the board to dust free conditions temperature controled conditions with the temperature dropping gradually from around 75 degrees – taped the rails off well below the mid line – took as clean a piece of lint free cotton as I could find (old t-shirt) and wiped the board down with ethanol (board’s gott be clean/clean/clean!) – Let the ethanol evaporate – mixed my resin with additive “F” (I always put the additive in the hardener and mix it before I mix the whole batch) – Got out my favorite 2 inch Purdy bursh that I keep primo and brushed out the resin pouring it out much the same way you do for laminating – once the material was spread fairly evenly I brushed board twice in each direction finishing lengthwise. I touched a few of the thin spots with a little acid brush and pulled the tape in about an hour. The boards I’ve done have skinned beautifully.
Thanks Rich. It sounds like maybe I’m just not getting it perfectly clean. Although I’ve wiped the board all down with acetone before glossing - maybe I’m not careful enough with sanding…?
I’ll get my hands on some ethanol, resand and try one more time. I’ve got just enough epoxy left to do so.
If it dosen’t fly I’ll sand it out again and finish with Future. (arrgh! - shoulda been done last week!)
I had the exact same problem (pulling away in spots) when glossing once. I chalked it up as a contamination problem of sort. That is; either from me handling the board (oil/dirt on my hands) or maybe just didn’t clean or blow it off well enough.
Halycon outline an exact procedure that I use when applying epoxy over epoxy. I *sand/scuff with as low as 100 and do a wipe down that’s very similar. I also use disposable brushes - more for ease than anything, but I also think things can get contaminated when using solvents to clean used brushes.
*A lot of people say you can skip scuffing if you’re laying within 24 hours, but it’s such a simple step, why pass on it? I also think the scuffing helps break up any possible surface tension problems when applying additional layers - and also scuffing promote better adhesion in my mind.
Maybe Halycon, Bert, or another pro could help with my latter comments. These are just my thoughts and don’t really have any scientific backing for them.
Stay away from acetone whey your using epoxy. There’s no need for it. Ethanol is your solvent for clean up on brushes and everything else.
No need to scuff the surface if it’s fresh, that is less than 48 hours old. Just wipe it down with ethanol and go for it. I just clean up the bumps on the laps a little with a course file and some 60 grit after doing the bottom and do the same when the lamination is finished before the hot coat. I go to about 150 so the hot coat skins over nice, but that’s about all there is to it. You just have to wipe carefully and don’t touch the surface before you shoot the sanding coat.
They say Epoxy doesn’t polish well. I’ve never tried it. a second hot coat after sanding might give a surface that could be sanded down to 600 grit and a then a polishing compound used at a very slow speed. I don’t this it would be a good idea to attempt the same polishing techniques that are used with poly. Another alternative is laquer based polyurethane. I see Hiberglass Hawaii has the high gloss stuff in quarts now. It would spray on great and leave a very nice finish. I’m not much for sparying laquer so I may try brushing it and see how it levels.
Everything must be clean. That’s the board, the room, the brush, the bucket and everything else that might come in contact with the resin. Contamination will surely ruin your gloss coat.
I usually sand to 100 for glossing. I’ve seen others go to as far as 220 but I’ve never seen the advantage to the extra work. 100 is just fine.
You’ll never get a good gloss using a sqeegee, you have to use a brush. It takes a certain amount of resin for it to be able to “flow out”. Using too little and the resin can’t move and self level. This does add a bit more weight than getting it really thin but it’s the only way to get that show room finish. If you don’t want the extra weight then go for a sanded finish.
With Additive F you can polish RR epoxy. In fact it polishes just about like polyester. Without Additive F epoxy doesn’t polish well at all.
When glossing with epoxy double the amount of Additive F. This will give you better flow and your gloss will come out flatter.
As for urethane finishing, this takes really good equipment and a VERY clean spray booth with a constant flow of fresh air. Most of us aren’t set up to do this reasonably. I’ve done a good bit of this and it’s a real professional type of effort to even attempt it. As much as I did, I never had the equipment to get the consistant results I wanted. This is also VERY toxic.
I think it was a somewhat dirty surface. I use alcohol after cleaning thoroughly with a vacuum and clean cloths. As was mentioned, brush it on evenly and then brush two times each way…then walk away till you pull tape. Mine using this method(same as halycon…) have gotten better and better, granted I have only done 4 so far. I had some pin bubbles and pulls on the first few, but since I have cleaned more thoroughly I have had good sucess, comes out nice and shiny. Have fun…
My problem - I’m sure now - is the environment. I’m shaping, lamming, sanding and glossing in the same dusty shed. Not much I can do about that right now. I can surely live with a few zits, but not the pulls and runs. I’ll clean up as best I can and give it another shot.
Worst would be sanding -again- out to a fine grit and finishing with Future. Which looks fine to me. Except that on one board I’ve made I have a decent swirl color design which will only look it’s best with a gloss.
Also - Rich, Acetone seems to work fine on epoxy. I know it’s ‘dirty’ stuff, but I have it on hand and until I can get my hands on ethanol it’s the only game in town.
Thanks again everyone - off to the shed again tonight.
The dry spots on the rails are probably from oil in your hands. All hands have a certain amount fo oil. Wiping the board down with denatured alcohol will help remove this. By the way, denatured alcohol is ethenol with 5% wood alcohol which makes it poison. They put a small amount in so people can’t drink it since ethenol (grain alcohol) is what is in alcoholic beverages.
Rubbing alcohol tends to leave behind a film. That’s why it’s not good to use to clean camera lens. I don’t know how much this might effect a glass job on a board, but I doubt that it would help.
Try using a ‘tack’ cloth. They pick up EVERYTHING (dust, sanding grit, etc.) and also reduce/eliminate STATIC ELECTRICITY (which might be repelling the epoxy from those spots you mentioned).
Tack cloths are available at hardware stores. They are used when working on urethane floors, for example, when it is very important to get the surface as CLEAN as possible. Cost less than $1 for one tack cloth and that is more than enough for one board.
Pure acetone is quite toxic if you breath its fumes or drink it, but not too toxic on unbroken skin.
When hand sanding, it really easy to leave behind greasy grimey paw prints as you hold the board with non-sanding hand. Also, some sandpaper has a stearate coating that can affect finish coats. I even wonder if flipping sandpaper over can transmit grease from your hand? Store bought “tack rags” may contain substances that can give problems. For final sanding, use fresh uncoated sandpaper and wear rubber gloves.
You can take a single edge razor blade and scrape the bead off where the tape was. You can take a block with sandpaper on it and take it down by hand. 150 grit would work fine. Use a light touch.
Cool , thanks. After taking it down, do you buff it out, or leave it dull? Since it was the “gloss” coat, the final coat? I mean, my gloss job comes out perfect, like a mirror(finally…). Except for the slight ridge left on the tape line(rail center) after glossing both sides. So just sand and buff the rail center? How do you do it? Thanks…