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We used hand sanders for roughing and hand sanding with 16 grit paper.
Final roughness of the surface depends an the type of glass and the resin system.
If you ever have to buy a motor for the compressor buy a Totally enclosed motor. (TEC) it is safer in a paint environment as it's close to the explosion proof motors which are super expensive. The TEC motors will not suck in dust as regular motors do.
I've got some 16 grit disks, tomorrow I'll try hand sanding with one of those.
I know we all have different ways and suggestions...but honesty. I use MIRKA sand paper and do not have an issue with it. Regardless if it is for my D/A or my long board. I also use the 3" Rol-Loc discs of different grits from 24,36, 60 and 80 grit.
AS I wrote...keeping your sandpaper and cold as possible will make it last longer...but that also depends on the grit. So trying to use 320 grit D/A paper to sand down rough VPA is the WRONG grit to use.
Not knowing what tools you are using to do your rough grinding and sanding would help if you can post some photos...because it may be the tool that it the problem for what you are doing, Unless you have it all figured out and are onto the next step.
Although I am a 'tool *****'...I do know that those files could be handy in some specific areas.
When working on surfboards and sailboats with fiberglass we used a hand tool called a surf form.
Anyone still use these on fiberglass?
I use a similar one on sheetrock to finish the edges.
This site has lots of surfing power tools also.
I'd be interested to hear from anyone using these now.
I know we all have different ways and suggestions...but honesty. I use MIRKA sand paper and do not have an issue with it. Regardless if it is for my D/A or my long board. I also use the 3" Rol-Loc discs of different grits from 24,36, 60 and 80 grit.
AS I wrote...keeping your sandpaper and cold as possible will make it last longer...but that also depends on the grit. So trying to use 320 grit D/A paper to sand down rough VPA is the WRONG grit to use.
Not knowing what tools you are using to do your rough grinding and sanding would help if you can post some photos...because it may be the tool that it the problem for what you are doing, Unless you have it all figured out and are onto the next step.
Although I am a 'tool *****'...I do know that those files could be handy in some specific areas.
DUB
Trying to sand rough VPA with 320 made me smile Dub. Like you always reminded me, VPA has a time frame where you can actually work it but it's not to long and once it rocks up well the train has left the station with 320. Hell you'll have fun with 80 grit and rocked up VPA. Don't ask me how I know.
RVZIO
Here's what I've been using to get a rough texture on the 70-73 ACI rear clip to join to the 79:
24 grit on the air sanders and 40 grit on the inline sander
And here's the result after hand sanding with a 24 grit air sander disc. The lower 1/3 of the pictures is the unsanded interior finish of the hand laid fiberglass. It looks a little rougher in person:
Here's the bonding seams on the 79 sanded with 40 grit on the inline sander - noticeably rougher than the 24 grit hand sanding on the 70-73 ACI rear clip. Once again, looks a little rougher in person than in the pictures:
Your air sanders are JUST FINE! Getting a rough surface will have to do with technique and NOT the tool itself. Because I have sanders just like those you posted photos of and I have no problems at all gettign surfaces prepped....so I know you can also.
Keep in mind that all surfaces do not ALWAYS have to be so rough you get cut just by wiping your hand over them.
My only concern I have is what I see in you sanded laminated quarter seams where you applied the West Systems resin. In the photo below I am see quite a few rather large air bubbles that have been sanded on and exposed. Honestly if I had to do this I would not care about it being blocked and flat. I could get it flat enough for me to grind the heck out of it and skim coat it in VPA.
My other major concern is seeing resin on top of what look like the original paint. That is a disaster just waiting to happen if that is left like that. This is why I often time will let people know to not be afraid to take more paint off than they feel they need to so when they laminate...their laminated area stays within a prepped area.
I was disappointed at all the air bubbles as well, I haven't had a problem with this in the past. Even though I used close to the recommend amount of hardener (5 pumps resin, 4 pumps hardener) it was still soft five hours later and with the resin at room temperature a lot of the resin ran out of the mat before it hardened so I will be putting VPA over it. Also, I left the original paint there as a guide to know when I sanded down to the proper level. I will be removing all the paint on the quarters with 120 grit after I finish the fiberglass work to join the 70-73 ACI rear clip to the 79 quarter panels.
I hand laid fiberglass to fill in the channel when I flared the fenders on mine. Quickly learned hand sanding was not going to cut down glass resin or VPA. Keep up the good work.
Last edited by rajin cajin; 04-09-2017 at 06:41 PM.
I always pump each material the same number of pumps...and that is using the correct ratio pump for each material also. By cutting back on one pump reduces the hardener by 20% of what it normally would take. I do know that reducing the amount of hardener in some products is quite acceptable...and they can still cure out...and I do it. But I also use infrared heaters and other measures to make sure that what I am doing is still going to work due to me modifying the ratio of hardener to resin or whatever it is I am modifying.
I seriously doubt that the resin ran out and caused for air bubbles to develop....especially if a roller was used to apply the mat and resin and work the air out.
Do as you wish in how you are going to deal with the remaining factory paint. I have a different method that would require removing the factory paint all the way to the top of the quarter panel styling line and then apply the VPA all the way to that top where I had prepped is so when I go and block the seam....it comes out looking something like this from '7Stingray1's' thread. And trust me...it is easier to get the seam right by doing it this way instead to trying to keep the work area smaller.
Quickly learned hand sanding was not going to cut down glass resin or VPA. Keep up the good work.
I agree with using air grinder on mat and resin when needed....But...for whatever this is worth to those reading this... I hand block sand VPA all the time when it is my final coat and that layer is what I am trying to get shaped correctly. The 'trick' with VPA is knowing when to go in with your sandpaper and get it roughed in. If you wait too long...and what you applied looks like stucco....you WILL regret it. This is when I do not care about sandpaper costs.
I went over the inside of the 70-73 ACI rear clip today by hand with a 16 grit disc. I quickly got the sort of roughness I was after. I thought I had about ten 16 grit discs but it turns out I only had one so I'm going shopping tomorrow to hopefully find more. The last time I bought them was about 25 years ago and they were very hard to find then but I suppose nowadays I can probably find them on the internet if I can't get them locally.
I tried to sand away the bonding strip on the inside of the 79's rear quarters. It was really slow going with the 24 grit to my surprise. The 16 grit took it down quickly though. I haven't used the 16 grit discs for probably about 20 years, I didn't think I'd ever really have a need for them again, but I was wrong.
My husband is hoping I'll have the back done and the car driveable again by the end of May. I'm feeling the pressure but I don't think there's any way I'll have it close to done by that time. He's frustrated that he can't use his garage. I regret starting a project that keeps him out of there for so long.
[QUOTE=Priya;1594500021]I went over the inside of the 70-73 ACI rear clip today by hand with a 16 grit disc. I quickly got the sort of roughness I was after. I thought I had about ten 16 grit discs but it turns out I only had one so I'm going shopping tomorrow to hopefully find more. The last time I bought them was about 25 years ago and they were very hard to find then but I suppose nowadays I can probably find them on the internet if I can't get them locally.
Mc Master- Carr has the disks in all sizes and grits. They ship quick and may have a store local.
Be careful of imported disks - poor adhesion to the backing and they may split at the glue joints.
04-06-2017, 11:26 PM
