APS body buck coating

[sofadriver]

The Buddfab streamlined motorcycle site is now gone (darn!).

I remember them saying they simply coated their body buck with gloss house paint, applied release wax and glassed it. Seems almost too easy.

Anyone ever done this?

Did they use latex paint?

Were they using epoxy or poly resins? Does it matter?

[4-barrel Mike]

On the way back machine: https://web.archive.org/web/20140517043743/http://buddfab.net/

I didn't check to see if everything was preserved on that capture.  If not, check one of the other captures linked at the top of the page linked above.   

Mike

[RichFox]

I think you could call John at 650-591-2515 or buddfab@yahoo.com and get the answer from the horses mouth

[sofadriver]

Wow! Thanks a ton, guys!

I don't like to bother people but I will give him a call.

The big question was answered in that web archive - Yes, they did use latex paint. On the last body, I covered it all with adhesive-backed aluminum tape. It worked great but was labor intensive.

[davidd]

The Buddfab streamlined motorcycle site is now gone (darn!).

I remember them saying they simply coated their body buck with gloss house paint, applied release wax and glassed it. Seems almost too easy.

Anyone ever done this?

Did they use latex paint?

Were they using epoxy or poly resins? Does it matter?

Yes, I have laid glass over many things, including house paint, oil and latex. I would not recommend it using wax only. Wax is quite porous and will allow some chemical transfer between the plug (buck) and the mold. This can cause separation anxiety. However, if you use PVA over the wax, you can do anything. PVA (Poly Vinyl Alcohol) is easy to get, easy to apply and impervious to most chemicals. I spray it on the plug. It is alcohol based so it is water soluble. So, spray many light coats so it doesn't run. If it runs and turns into a mess, hose it off and do it again. You can brush it on also.

If you spray a good thick coat, it will peel of the mold in a giant sheet that will look like Saran Wrap. If it is too thin to pull off in a sheet, just hose down the mold rubbing it with your hand. The PVA will dissolve and feel quite slippery. As it disappears, the mold will just feel wet. PVA is usually green in color and sold in a jug.

You can use any resin for the mold because its bulk will provide most of the strength. Cheap polyester is OK. If you want maximum chemical resistance, flexibility and strength, I would use vinyl ester resin. It is more expensive than polyester, but I like its performance for body parts. You can buy from any fiberglass or marine supply store of get it on line. I use Glue Products in Florida. Prices are reasonable, they ship and the quality is good. I use their PVA also.

http://www.glueproducts.com/

David

[sofadriver]

 I spray it on the plug. It is alcohol based so it is water soluble. So, spray many light coats so it doesn't run. If it runs and turns into a mess, hose it off and do it again. You can brush it on also.




[/quote]

Thanks David
I'm getting the idea that PVA dries to a soluble membrane. So can you brush or roll multiple coats without pulling up the first coat? I can't spray anything in my shop (which is actually a 12x24 storage unit  )

[tauruck]

My experience is that it doesn't work. You'll have problems using a brush on multiple layers.

[Frenchinjection]

All the body work on our bike was made in house using Bees Wax mould release.  Adding PVA over the top helps crack it our of the mould but we didn't need it.  Look at www.saltbike775.co.uk for pictures of the bodywork in the making

[davidd]

I agree with both posts. When you spray on the PVA you can do multiple coats because the latest layer will meld into the previous layers and turn into one film. So, when you brush on multiple layers the brushing will upset the earlier layering and make a mess. If you are brushing, use a foam brush and bush just enough to coat thoroughly and move on. The PVA will thicken as you work it and the alcohol evaporates.

https://www.youtube.com/watch?v=hr-GSpo1jbc

Wax will work fine if you are doing a nice job. But I have had paint and body putty stick to the mold right through wax and it takes quite a while to chisel it off, never mind getting it off the plug. If you leave plenty of time for all the solvents to gas off and you put four layers of wax on, you should not have a problem. If you are doing something out of the ordinary I would consider using PVA.

David

[sofadriver]

I guess the only real way to find out about PVA is to buy a small amount and fool around with it a bit.

[tauruck]

David is right and so is Frenchinjection.

If the surface of your plug is porous you're going to have problems no matter what you use.
In mold making you're going to get a reverse part of whatever you're molding and repairing molds
isn't fun.
If the plug is well finished you'll need to polish it well and one layer of PVA will suffice.
Unfortunately there are no shortcuts in composites.
I'm not sure what your plug is made from but a few thick coats of spray filler should kill any porosity
left by Bondo or other fillers. Porosity is what will make the mold difficult to release.