Wet Sanding

[recon]

Are there any secrets to wet sanding? Or is it just the way it sounds? How wet should the surface/paper be? Im new to cowls and wheel pants and have not really wet sanded before. Thanks for your help.

[Kevin McGrath]

Yes its pretty much the way it sounds,and experience will teach you quickly how wet is wet enough.Use the black waterproof paper in grits from say 240 to 400 or finer,depending what you are sanding,how rough it is and how smooth you are trying to get the work.If you are working on typical seams in cowls or pants,in either plastic or glass you will probably have to fill the seam more than once and sand between fillings.Usually small defects will show up in these seams when you prime them before painting and these will have to be filled and wet sanded again for a perfect job........depends how demanding you are! :wink:

[scaleguy]

Bradly,

Wet the paper! Rinse it out from time to time to open up the surface of the paper. Especially on finer paper like 400 or 600 the surface clogs up with material quickly!

[AJCoholic]

On parts that are not too big I like to do my wet sanding under the tap in a laundry tub. Set the faucet to a heavy trickle and it is enough to constantly keep theresidue washed awaya nd out of the paper.

Andrew

[supercub Man]

You should use enough water to create a "slurry". This is a mix of water and the finely sanded material you are working on. Rinse the wet/dry sandpaper off frequently, either under a tap or swish it in a bowl of water. Keep the paper clean. Check the surface you are sanding by wiping it off with a wet cloth if it is large like a wing, or run it under the tap if it is small like wheel pants or cowl. Use a 250 to 400 to 600 to 800 grit wet/dry paper to achieve the degree of smoothness you want. I usually start with a 250 grit on fiberglas and 400 on open framewrok cloth. Sometimes, like on the seams in a cowl, hand sanding will leave high spots on the ridges. You need the hard suface of the sanding stick to really smooth them out. I adhere the wet/dry paper to an aluminum "T Bar" sanding stick with Elmers Spray Contact Cement ('cause it's the cheapest - you don't need 3M stuff for this application) and run the stick under the tap to keep it clean. Rinse then dry with a towel and fill the low areas and water sand it again. The last sanding can be with real fine grade wet/dry used wet on a primer. Let any fiber glass parts that you "really soak" dry for 24 to 48 hrs. to be sure all the water has evaporated out. On a wing, run the paper over the rib cap strip "ONLY ONCE". Sand the bays between the ribs being careful not to "cut" through the covering at the edge of the cap strip. A light pressure with lots of "slurry" does the trick. You only need a light "going over" between coats. If the wing is sheeted, of course you can be less careful. But water sanding really cuts fast - so just be careful!
Works for me. Hope it helps for you!