Quick finishing question

Signed-In Members Don't See This Ad
hertzogcraig

hertzogcraig

Member
Joined
Mar 15, 2024
Messages
106
Location
Dillsburg, PA
So in alot of my embedded resin projects, I'm getting these white spots and not sure why, can anyone help me out? I've tried wet sanding, dry sanding, meticulously filling every little pit with CA before and after sanding, I still keep getting them. Can anyone help me figure out why and how to stop it? Sorry if this is an obvious thing and I'm just missing something
 

Attachments

  • IMG_0965.jpg
    IMG_0965.jpg
    149.4 KB · Views: 68
  • IMG_1099.jpg
    IMG_1099.jpg
    234.5 KB · Views: 61
  • IMG_1098.jpg
    IMG_1098.jpg
    227.9 KB · Views: 65
Signed-In Members Don't See This Ad
It looks to me like there might be voids where your getting dust collecting. If that's the case when you're through turning look and make sure the surface is smooth. Use compressed air to blow off your project. If you use water or DNA the dust will darken and be hard to see so make sure it dry. Fill any voids with CA then start sanding.
 
Thats what I thought too, but I had filled the voids with CA before this. Who knows, maybe I missed some, but I can't believe I had/missed that many
 
In my case sometimes I fill the voids and when sanding down those spots I open up new ones. The pictures look like you cast a somewhat porous material. If so that may be the case. What I do is when I get to the final sanding process, wet sanding, I start coating the whole thing with CA. Then when I get a level surface I start my finishing.
 
Kenny Durrant said:
In my case sometimes I fill the voids and when sanding down those spots I open up new ones. The pictures look like you cast a somewhat porous material. If so that may be the case. What I do is when I get to the final sanding process, wet sanding, I start coating the whole thing with CA. Then when I get a level surface I start my finishing.
Click to expand...
Yeah this is coffee beans. I'll try using more CA and see if that helps. Thanks
 
Are you using a pressure pot? From my experience and what I think see there it might be moisture in the resin. I saw this in greater evidence on a much larger casting solved in my case with a moisture trap on my compressor . Just my thought đź‘Ť
calabrese55
 
Also, I've found that even tiny-tiny ones, nearly invisible pinhole becomes obvious as a white dot whenever I use any kind of liquid polish. The polish gets in there and then dries to a white spot that (for me at least) seems to be virtually impossible to remove. Sometimes they are unavoidable, but I minimized their appearance when I went to buffing instead of using liquid polishes. - Dave
 
As Kenny wrote, "If that's the case when you're through turning look and make sure the surface is smooth." While many people use paper towel as the applicator successfully, I had problems with it as it did not apply silky smooth layers for me, and that sometimes led to white spots. I use foam applicators, or small pen parts bags or even latex gloves to smooth the CA, usually medium CA. That does require a bit more curing time. But when it is applied with smooth layers (for me) I have no problems with pits or pin holes in the CA.

One other factor is temp and humidity. Temps in the low 70°s and lower with high humidity - that also increase chances of white spots. These white spots are due specifically to temp and humidity and are on the surface and can be fine sanded off if a smooth surface was applied. See below

www.penturners.org

Imported Photo from leehljp

Imported Photo from leehljp. Please edit title and description.
www.penturners.org
www.penturners.org

Imported Photo from leehljp

Imported Photo from leehljp. Please edit title and description.
www.penturners.org
 
egnald said:
Also, I've found that even tiny-tiny ones, nearly invisible pinhole becomes obvious as a white dot whenever I use any kind of liquid polish. The polish gets in there and then dries to a white spot that (for me at least) seems to be virtually impossible to remove. Sometimes they are unavoidable, but I minimized their appearance when I went to buffing instead of using liquid polishes. - Dave
Click to expand...
Yes, that's exactly when they show up, after using Yorkshire grit
 
leehljp said:
As Kenny wrote, "If that's the case when you're through turning look and make sure the surface is smooth." While many people use paper towel as the applicator successfully, I had problems with it as it did not apply silky smooth layers for me, and that sometimes led to white spots. I use foam applicators, or small pen parts bags or even latex gloves to smooth the CA, usually medium CA. That does require a bit more curing time. But when it is applied with smooth layers (for me) I have no problems with pits or pin holes in the CA.

One other factor is temp and humidity. Temps in the low 70°s and lower with high humidity - that also increase chances of white spots. These white spots are due specifically to temp and humidity and are on the surface and can be fine sanded off if a smooth surface was applied. See below

www.penturners.org

Imported Photo from leehljp

Imported Photo from leehljp. Please edit title and description.
www.penturners.org
www.penturners.org

Imported Photo from leehljp

Imported Photo from leehljp. Please edit title and description.
www.penturners.org
Click to expand...
I switched to applying the CA with a gloves finger for this reason too
 
Using a very thin CA and wiping it on the blank while the lathe is stopped will help you get it on those small holes. Once you've found them you may need to fill each one individually if they are too deep. Then build your finish layers over them. It's very common with some embedded object casts.
 
JohnU said:
Using a very thin CA and wiping it on the blank while the lathe is stopped will help you get it on those small holes. Once you've found them you may need to fill each one individually if they are too deep. Then build your finish layers over them. It's very common with some embedded object casts.
Click to expand...
Sounds like I need to use more CA on these things than I was. Thank you all so much for the help, it was driving me nuts
 
You must log in or register to reply here.
Back
Top Bottom