Ive read through the archives on everything i could find on the topic but decided to start a thread for some more personal inputs (hopefully)
I am having some major problems with millions of very tiny pinholes when i polish my glosscoats, especially show up on dark tints since the holes get filled up with polishing compound.
So heres how I do it:
laminating the board, squeegee a clear coat of lam resin to avoid a too dry lam.
* hotcoat
sanding 80/120
clean the room and the board thoroughly. (compressed air, walking the board up and down with a pair of new gloves, wipe it with a piece of tape)
glossing the board in a heated room (21-22 celsius/ 70f ?) with a mix of 5% styrene/5% wax in styrene/ uv hardener and 2% Mekp. I wait until it has evened out then i flash it with a sunbed that i got mounted in the ceiling for 30 secs. (I can’t get real gloss resin in the part of the world i live)
letting it cure for 2-3 days on the racks
sand it dry 400/600/800, wet 800/1000/1200/1500
Using a wool bonnet for compound/polish.
So here’s when the problems start to show, once it goes from a matte finish to a more glossy look.
The boards are filled with tiny tiny pinholes and now ive reached the point of not knowing what to do or what to do different.
The gloss looks good, and isn’t filled with dust (what i can see at least)
I use a new brush for every gloss run I do. Usually shape and glass 3-4 boards at a time. So 1 brush for 1-2 boards, its soaked in acetone between use.
Blowing the dust out of the holes does not work.
Attaching a picture below on how it looks on a dark board. Lighter tints have them as well but does not show anywhere close to dark ones.
Possibly old resin (I had that problem a while back with similar results). Possibly wax wasn’t fully dissolved. Possibly air whipped into the resin when you mixed it making little bubbles. Those are the possibilities I can think of. A quick wipe with acetone or styrene might make it disappear. I’m sure others will chime in who’ve run into your issue.
I wiped with styrene and they don’t fully disappear but show a little less. Problem is that the polished surface gets a odd matte look and once you polish it again everything is back to where i started.
I have thought about the the wax not being fully dissolved and will try to keep it in a warmer room for a couple of days before next gloss.
Many years ago I had the same problem , it turned out to be the cloth was the culprit , for some reason the cloth would not fully saturate , different cloth no problem . good luck .
Everything shows on a dark lam. Those type of pinholes are usually a case of trapped air. In the early 90’s myself and a couple of other glassers I knew tried UV Gloss. We found it to be problematic. We went back to Catalyzed Gloss Reichold. When you “Flash” the UV Gloss, you seal the surface but air is trapped beneath the skin of the UV Gloss resin. The air and gasses escape via tiny bubbles. The bubbles pop and form pinholes. Also when you flash UV Gloss you are not giving the resin an opportunity to flow out and level. If the resin doesn’t level, it is much harder to sand. I wouldn’t use UV for gloss. It’s fine for a hotcoat. If you do use UV in your Gloss, let it set for 20 or 30minutes before you flash it. It’s always been my experience that you do not have to let a UV board cure.
That makes sense. I usually wait for 5-10 minutes before I flash it. Will skip the UV powder on next batch of boards and just let it cure. Thing is that I am usually having a little problem with 2-3 streaks from the brush that I need to take extra care of at the 400 grit to get flat.
What causes crystallization?
Does 5% wax/5% styrene sound right? Have been thinking it could be a little too much wax.
Thanks for the input regarding that it could also be the cloth. I had this problem with both Hexcel and Aerialite cloth.
I don’t think it is the cloth. I like both, but prefer BGF Aerialite. I use Wax/Styrene solution and it is 5% wax in Styrene. I am pretty lax with my measurements. If you are using a Gloss Resin, technically you would not need Wax & Styrene as it already contains both. There is a formula going around here on Swaylocks that suggests extra wax and Styrene. I even add a little Acetone. It helps thin out the resin so that it spreads better. I don’t believe you are overdoing the Wax/Styrene.
The specks are pits caused from micro bubbles trapped just below the wax layer and opened up when fine sanded. Use 100% finishing resin at 60 degrees or more and you won’t get those. Sanding resin (waxed laminating) will usually give you pits.
If you’re in a location where you can’t get gloss resin then disregard
Excepting a flawed finish and rubbing something on the surface to hide it might be setting the bar a little low.
I would try heating just the wax additive to make sure the wax is dissolved before mixing with resin. Then heat the batch to 70 degrees. Maybe pour it through a fine mesh filter cone after mixing with catalyst. 70 degrees sounds good but if you stir too briskly, introducing air bubbles and then place under UV lamps, the temperature might rise and cause any remaining bubbles to enlarge. Try keeping the temperature constant until the resin is ‘set.’ Also, try stirring slowly to introduce less air in the mix. There are even vacuum cannisters in which you can place your resin pot to pull out excess air before using. When brushing the resin out, don’t get too aggressive with your brushing technique. I know that with epoxy for instance, aggressive use of a squeegee can introduce a ‘froth’ that is basically little bubbles trapped in the resin.
Use black polish compounds to polish dark boards, you can buy automotive products for light or dark cars. If you get those tiny holes use the compressor to blow the sanding dust out of them. Sand to your desired grit…like 500+, then use a dark polish to finish the luster. the holes will fill with the dark polish and will be less noticable. …" less noticable only"
Since you can’t get gloss resin Johns method sounds like a good start.
i would also add a fair amount of styrene also so it’s a thinner coat. I’ve found that wherever resin pools and is thicker you’re more likely to get the bubbles (specks).
I believe the micro bubbles are a chemical reaction as opposed to foreign matter or rigorous mixing, but minding those things can’t hurt.
I used a few drops of baby oil and rubbed the area with white pinholes and 90% disappeared. I will try to get a hold of some polish for black cars. I think that it’s my cutting compound that first fills the holes with the dried compound and I can only find black polish for that final touch.
Found out that turtle wax has a “black edition” with several products for black and dark cars.
My main goal is, of course, to not get the pinholes at all so I will do a few changes on the next gloss.
If anyone else has had this problem feel free to add more potential reasons/solutions
Got a feeling that I have flashed the gloss way too early, will just let it cure with MEKP only next time and make sure the wax is not too cold.
I think this was recently discussed in another thread. I would just take some acryic paint and wipe it into holes, then maybe seal it with some polish. I think you just need to “stain” the powder left in the micro pits/holes. If they’re bubbles under the surface that’s another story.
If your Gloss coat is layed on nice and sanded properly; You should be able to go straight to polish. Don’t use a rubbing compound if you can get out of it. Never use the Red compound and never use a light colored compound on a dark board. If you need to get rid of “Swirls” use 3M Perfect It. If you sand properly and go thru the grits you shouldn’t have Swirls or scratches. I like to use an Orbital Sander on the last grit or hand sand it wet. I use plain old #2 Fiberglass Polish. Used to always use a wool bonnet, but have been using the foamies the last few years. Lowel
