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Question about wet sanding urethane paint

Posted: December 28, 2015, 8:34 pm
by tomrooster
I painted with single stage urethane and used there hardener in proper amount and got some orange peel here and there that I need to remove so I saw a tip that you soak the paper ,1200 , and I did and it works good if I hand sand but if I use a block sanding board the paper clogs up quickly. Is there a cure for that cause I would like to block the flat parts. Thanks Tom

Re: Question about wet sanding urethane paint

Posted: December 28, 2015, 9:32 pm
by jamesdfo
Tom: Some tricks used by various painters:

Sponge & bucket of water, sponge in one hand, sanding block in the other

Spray bottle of water in one hand, sanding block in the other

not as likely to be used in a home garage, but in the shop, it was common to just have the garden hose in one hand trickling water over the panel while you wet sanded......

there's no magic, just lots of work and enough water to help flow the sanding dust away as you work

Re: Question about wet sanding urethane paint

Posted: December 29, 2015, 12:23 am
by 36truck
The paint might need to cure more to harden all the way. How long ago was it painted? How thick were the coats?

Re: Question about wet sanding urethane paint

Posted: December 29, 2015, 12:44 am
by FORDMANLCRACKEL
As jamesdfo said plus, after the 1200, wet sand again with 1500 and then 2000 squeegee of the water often to see if you have sanded of enough of the orange peel to stop sanding. Listen to and feel what the sand paper is doing. If it sound like some grit is under the sand paper git rid of the grit and continue sanding. There should not be any shiny spots where you have sanded then do your first buff, whipe off with dry soft cloth just like you would if you were waxing. Then do second polishing buff. There is a 3rd step if you feel that it is needed. I would do the intire truck so it would all match. Be careful on the edges with the sanding and buffing. Most of the buffing compounds and polishes have step 1 step 2 and step 3 on the container and tell what buffing pad to use with each. The compound and polish will dry pretty guick while you are buffing, so when that starts to happen i spray a mist of water with a spray bottle and it will loosen the compound and you can go a little further. Keep the buffing pad moving or you may burn the paint. DO Not wax the paint for at least 6 months so all the solvents have pleanty of time to dry! Hope this helps!

Lonnie

Re: Question about wet sanding urethane paint

Posted: December 29, 2015, 8:47 am
by longcabjohn
Don't know about now but back in the 70's we put a little soap in the bucket. One old painter I worked with would drop a bar of Ivory in, with him nothing else would do.


Johnny

Re: Question about wet sanding urethane paint

Posted: December 29, 2015, 9:20 am
by 64 f100
Dish washing detergent will help keep the sandpaper clean. I use dawn but cheapest will work. Been using it for years and learned it from older body shop workers. Runs, use single edged razor blade to scrape most of the run down smooth. Hold it leaning back not into the run. Scrape from different directions not all in one direction or you will end up having dips. Finish with sanding block or small block of wood with sandpaper wrapped around it.

Re: Question about wet sanding urethane paint

Posted: December 30, 2015, 4:41 pm
by grump
Your hand is a lot softer than a rubber block so that could make a difference. I use a semi soft block to color sand with, it will bend but not be floppy. As every one has said dish soap in the water makes a difference and when you are buffing it might help you if you put tape on your edges to keep from burning through your edges and body lines. If you finish sand with 2000 grit you can hand buff your edges and body lines fairly easily. As has been brought up the paint could need a little more dry time, especially in this kind of weather, if the temps get below a certain level before the hardener has done it's job the hardener process stops. I think PPG is 50*. It used to be that after a couple hours you could turn down the heat and go home but it doesn't work that way any more. That temp is the temp of the metal. Hope this helps.

Re: Question about wet sanding urethane paint

Posted: December 30, 2015, 8:28 pm
by mercuryv8
And just to be different I use a small very hard block, a hockey puck with two sides cut off. Like James said I run the garden hose or 5gal of soapy water.

Nic

Re: Question about wet sanding urethane paint

Posted: December 30, 2015, 8:37 pm
by tomrooster
Thanks for the advice, Tom