Tiny Pinholes

General Discussion
1

Have you had any issues with tiny pinholes in the board after it is finish sanded? 

I have had this issue twice recently. The hot coat goes on perfectly but when I’m sanding I find a small patch of pinholes/ tiny divits just enough to feel but hardly see. 

It just happens in a small patch, not everywhere. 

Is it a contamination issue?   But why in just one area?

Also, what kind of 40 or 60 grit sanding pads for the air compressor sander attachment do you use?  Forgive me, but I don’t know the name of that tool just know how to use it?

Where do you buy yours? Anywhere online?

 

thanks a bunch!

@windywind

2

WELCOME back.

  glad to see you are making boards , still …

 

I have trouble with pinHEADS here

 

cheers !

 

 ben

3

Maybe air bubbles from mixing too vigorously?

4

windy wind

 

how are you?

all is well with me, life is good

you may be pulling your lam too tight and not leaving enough resin to fill between the weave,

EDIT: dont let the lam cure too slow as the blank will suck in the resin and you can get a dry lam.

you may be using sun cure , best to cure it slow, in and out of the sun as not to gas the blank and make volcanos especialy durring hot coat

if epoxy, do your fill coat as the temps drop as not to gas the blank

hope this helps

peace

Ken

 

5

Are you talking about the grinding discs for a lap grinder? Pnuematic die grinder? If so surf supply has them, so does HArbor freight. The best ones come from auto body supply shops, We buy ours off the Mac tools truck that comes through.

6

I quit using my die grinder and went to a Porter Cable random orbit sander. I use 80 grit Mirka white 5" PSA discs that I bought on Amazon. I find that I have more control. I only use the edge of the pad. This setup is also good for sanding rails and opening up the slots when sanding a board with FCS fusion boxes.

     The pinholes originally asked about are usually what we call “pin air”. The lam is to dry.


7

I reckon none of you were around when the Clark Foam disaster happened in 1990-1; those were some good times.

 

8

Yeah holly crap.

I mean holey crap.

Those were some gassy blanks.

Grubby said we were all using too much MEK.

He made some changes and it all went away.

But never fessed up to it.

Could have used some Solar-ez then huh?

9

Grubby never fessed up to anything.

His hard headedness is what led to his closure.

10

…is gassing due to the blanks+ humidity, for example blanks stored for long time in cold humid weather

Yesterday I glassed a board; all went perfect, today before sanding those micro bubbles started to appear…also delamed the stringer

I had a bad batch from Surfblanks Brazil + long storage with all the 70 blanks with this nightmare…lots of hours more to fix the fuckers. Salary for sweets…

11

Sometimes after cutting into older blanks, exposing the inner foam, heat will draw out the gas that is stored inside.

Seems to happen during the warmer months.

Gas only goes one direction. Up.

Glassing, especially the decks is best done as the air temp. is dropping as stated above. As the cooler temp seems to draw it inward.

That is an old trick I learned glassing epoxies years ago.

Those Surfblanks from Brazil use some weird wood that is full of oils.

Seen that before.

12

…I tested different possibilities: shaping a few, letting rest several days; pre heat them, dry them, Summer or Winter, etc nothing worked.

Yes, I laminated when the temp is dropping, actually all temps are low here. It s cold and humid; so I had all these glass well done with those dropped temps but next day when warm a bit nightmare begins.

In the middle I shaped a batch from Arctic that just arrived from there, nothing of this problem but the basswood stringers are a pain in the arse to work (they are not like the old Clarks basswood) and they are way heavier (and not stronger) than these other ones.

Today I shaped a Premium density one, that is a bit more difficult to shape due to the density; I mean, if you want a top quality shape without any mark or scratches.

13

@acuqa_ glassing yeah i have been buying them from Harbor Freight but they don’t last super long - I will check surf supply when I go there next.

Thank you @cleanlines i will go shopping for that white sand paper.  purple, green and all the other colors leave color stains.

btw where is the 3M god RESINHEAD!

14

Are you cleaning them? dip the face in acetone let the gummy resin bubble up. then blow it off, wipe it off etc. Acetone will kill the glue on the spindle and detach the disc.

The last time I bought harbor freight ones was 6 months ago if you keep em clean, they last a long long time. I think we still have all 4 or 5  in our rotation, and they get used daily. Literally if kept clean, you should easily be able to get 50-100 uses out of one disc.

Ironically the 3m ones fall apart the fastest, especially the ones with the yellow spindle,  the Spindles detatch  and the discs go flying. The ones off the truck, im not sure who makes but those can actually be 100 percent soaked in acetone without adversely affecting the glue, The ones they have at SS too.

15

thank you acqua glassing that is a great moneysaving technique!!!  I will do that right now.

The gummy resin builds up but half of the pad is still rough.  Thank you

good to know about the 3M ones… but they have sand paper and lord knows how much of that we go through!

16

Hi, could it be that your hot coat is going off a little too quickly?  I’ve had  instances where I made the batch too hot and it resulted in these “micropits” forming from the excess gasses generated.  Also, are you squeegeeing the laminate coat sufficientl? Leaving excess laminate coat on the glass could also lead to pockets of bubble-infused resin in your work.