White spots in fiberglass laminate

[jimmywayne]

last night i was laying a 8ft x 24 in in between the stringers from the stern up toward the front of my searay boat. I was sweating like a rain storm last night. Quite a few drips have made in the lay up. Now there is quite a few spots in the lay up. Kinda looks like dry spots in it. some of the spots are 2 inches in diameter. Do you think my sweat caused this to occur. i wiped myself with a rag a few times to try to reduce the drips getting on the laminate. Also when i was getting the excess resin out of the laminate it came out looking white. will these white spots weaken the laminate. I would hate for this laminate to break loose in the future as everything glassed to it would come off with it. engine mount and the glass going around the stringers. I am working with epoxy resin from uscomposites and 1208 biaxal mat. Any help would br greatly appreciated. Thanks jimmy.

 

[drewpster]

Re: White spots in fiberglass laminate

It is doubtful that the tiny amount of sweat is going to have any effect on the bond of the epoxy. After the epoxy cures use a scotch bright pad and a little water and scuff the surface off before you do any sanding for your next layers or doing any painting.
Did the cloth look translucent when you applied the resin? How did you remove the excess resin?

 

[jimmywayne]

Re: White spots in fiberglass laminate

Hey Drewpster thanks for the reply! I hope the sweat thing didnt sound like a joke. it was a lot of hot sweat dripping on that laminate. The high here in Decatur AL was 100 saturday But i know not to fiberglass in a rain storm. Yes the cloth did look translucent. I didnt look at every inch of it though. I removed the excess resin with a laminate roller. Heres what i done. I cut the piece to fit between the stringers ahead of time til i got ready for it i rolled it up and sat it on the table in my shop. I went out that evening when i got ready to use it. It was still about 90 degrees out. The humidity said about 70 percent. according to our weatherbug program i have on my computer. I noticed it had a few dirt spots and a lil fiberglass dust, not oil and it was only on the first foot of it. Darn it i should have cleaned that table I was able to blow it out without tearing up the cloth. So i vacuummed and acetoned the area. I used a new white rag to clean the boat. I mixed up a batch of resin and brushed it on the boat across the entire area with a chip brush. I laid the cloth and worked the wrinkles out of it by hand. I poured the rest of the resin that was left in the cup. I spread it across the glass with a bondo spreader. i then used those little pink corona rollers you get off uscomposites for sreading resin across the entire laminate. im sweating whille all this going After about 10 min i noticed white areas in the cloth. So i mixed up another batch of resin. I brushed it on. Those white spots wasnt disappearing. so i continued on rolling with the pink roller. after a couple of min i rolled out the air bubbles with the laminate roller. Thats when i noticed the resin was coming out looking white. I hope this didnt sound too confusing. This morning i went out to the boat and felt the cloth and the white spots. It all feels cured. What should i use to sand the cloth? Are those 36 grit flap disc good? Again Drewpster thanks for the quick response. I appreciate the advice

 

[drewpster]

Re: White spots in fiberglass laminate

What kind of cloth and epoxy are you using?

 

[drewpster]

Re: White spots in fiberglass laminate

I,m in Chattanooga, the heat has been a killer this week. I can certainly understand the sweat thing. Its like working in a warm bowl of soup around here these days.

 

[jimmywayne]

Re: White spots in fiberglass laminate

Hey drewp. Im actually reading your boat restoration now. Thats a nice shop you have. The shop i have is small i live in the city darn city ordinances want let me have a bigger shop. It gets a lil crammed up in there. I like that form you have made to set your hull on. i got my boat sitting on a bunk type trailer Im using uscomposites 635 thin epoxy system with the 3:1 hardener. The glass is 1208 biaxal mat.Ijust got it off the uscomposites website where i got the rest of my stuff. What would you recommend as far as sanding? I have an angle grinder and a belt sander The cloth is resting on the edges of my filets i have made for the stringers and i dont want to be too aggressive sanding it I understand the scotch pad and water thing to clean it before as to not spread the contaminates all over the surface. The white spots have never happened to me before. Ive patched a
few thin areas in the hull with this same stuff and it didnt have spots in it. Im wondering what caused it? Should i even worry about it? Again thanks for the replys Jimmy

 

[drewpster]

Re: White spots in fiberglass laminate

As long as you are sure you got everything saturated, I would not be concerned. If you are sanding for another layer of cloth I would use 150-180 and an orbital sander. You can use a backing pad on your grinder with a light grit. But I think the lightest you are going to find is still going to be to aggressive. The belt sander with a light grit may be ok. If you are sanding to paint 220 is fine. You just want to scuff to get the surface clean. You may want to look in to getting an orbital. They are pretty cheap at Harbor Frieght. I use a Dewalt and it has lasted a long time.

 

[jimmywayne]

Re: White spots in fiberglass laminate

Hey drewp. I really appreciate you helping me out on this situation i have been nervously sweating about! I will def get an orbiatal sander and the grits that you recomended using.
I just came back from home depot and the highest grit for the angle grinder was 100 grit Ive used an orbital at work and very pleased with the results when ive used it. I just need a bigger air comp in my garage. A sander like that is just a dead air bleed on that small comp. Again thanks for your advice now lets get out there and sweat!!! Hope you and me dont shrivel up like a raisin out in this heat!