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Building Tips and technical articles. => Paint and finishing => Topic started by: DanielGelinas on January 16, 2017, 10:48:00 AM

Title: Sanding paint with 400 grit
Post by: DanielGelinas on January 16, 2017, 10:48:00 AM
Hi guys,

I have a few cotes of coloured dope to remove from a plane.
Some of you suggested using 400 grit to remove the dope.
Would you remove the dope with wet or dry sandpaper?

When you finish a plane, when do you use the wet technique as opposed to the dry?

Thanks,

Dan
Title: Re: Sanding paint with 400 grit
Post by: Jim Oliver on January 17, 2017, 10:06:37 AM
Dan,
It will take a long time if you use 400 to remove the finish.

Is the subject a built up structure with silkspan or some other covering or is the subject all sheet?

If you sand the finish off you will probably cut into or through the covering causing additional work.

A technique that I have used is to get a roll of paper towels, a can of acetone, rubber gloves and (outdoors) wet the towels with acetone and wipe the dope off, changing towels as needed.

Don't soak the structure with acetone (may weaken glue joints) but keep the towel wet enough that the dope is softened enough to allow wiping off.

Messy and takes a while but, if careful, the covering can be saved with out damage to the structure. If you want to remove the covering, apply enough acetone to the covered area to soften the dope and allow the edge of the covering to be lifted.  I have removed wing covering one panel at a time using this method.

Hope this helps.
Title: Re: Sanding paint with 400 grit
Post by: Mike Haverly on January 17, 2017, 11:18:01 AM
What Jim said, works fine.  Wear a mask.
Title: Re: Sanding paint with 400 grit
Post by: TigreST on January 17, 2017, 08:40:07 PM
Dan,
It will take a long time if you use 400 to remove the finish.

Is the subject a built up structure with silkspan or some other covering or is the subject all sheet?

If you sand the finish off you will probably cut into or through the covering causing additional work.

A technique that I have used is to get a roll of paper towels, a can of acetone, rubber gloves and (outdoors) wet the towels with acetone and wipe the dope off, changing towels as needed.

Don't soak the structure with acetone (may weaken glue joints) but keep the towel wet enough that the dope is softened enough to allow wiping off.

Messy and takes a while but, if careful, the covering can be saved with out damage to the structure. If you want to remove the covering, apply enough acetone to the covered area to soften the dope and alloy the edge of the covering to be lifted.  I have removed wing covering one panel at a time using this method.

Hope this helps.

Ditto what Jim states, but I've used cheap lacquer thinners to effect the same result.  y1
Title: Re: Sanding paint with 400 grit
Post by: Allan Perret on January 18, 2017, 09:31:37 AM
Ditto what Jim states, but I've used cheap lacquer thinners to effect the same result.  y1
Ditto
Title: Re: Sanding paint with 400 grit
Post by: Mark Scarborough on January 18, 2017, 11:45:50 AM
Ditto what Jim states, but I've used cheap lacquer thinners to effect the same result.  y1

finally ,, someone who konws what to use cheap lacquer thinner for!! ( NOT IN THE PAINT)
Title: Re: Sanding paint with 400 grit
Post by: DanielGelinas on January 18, 2017, 07:28:10 PM
Thanks guys!
I never would have thought of that. I just have to strip a profile fuselage, so that will be easier than sanding...
Regards,
Dan H^^
Title: Re: Sanding paint with 400 grit
Post by: Mark Scarborough on January 18, 2017, 10:19:43 PM
Thanks guys!
I never would have thought of that. I just have to strip a profile fuselage, so that will be easier than sanding...
Regards,
Dan H^^

Lots of ventilation, NO fans unless they are blowing into the space,,
hand protection, good nitrile goves,,
Its really easy to get painfully high from strait thinner used that way, it evaporates fast! and that puts a lot of fumes in the air, and you wont notice it as easy as you would think, especially with a  respirator. I have stripped cars with straight thinner, ( yeah stuff goes wrong,, ) sometimes when you paint you blow it so you wash the fender or whatever down,,
anyway, just be overly cautious doing this,,
Title: Re: Sanding paint with 400 grit
Post by: Mike Haverly on January 19, 2017, 10:01:52 AM
Around these parts "cheap lacquer thinner" costs one dollar per gallon more than acetone.  Both work fine for this application.  I use acetone to thin polyester resin for boat repairs.
Title: Re: Sanding paint with 400 grit
Post by: Balsa Butcher on January 19, 2017, 06:45:50 PM
Since this is a sport plane w/profile fuselage do yourself a favor and just consider the previously applied dope a filler coat/primer, cover it w/a coat of light grey (polar grey and white combined) then spray your color and clear. The amount of weight you save completely stripping the fuselage isn't worth the effort and smelly mess that bathing it in stripper or lacquer thinner will make...just MHO.  8)
Title: Re: Sanding paint with 400 grit
Post by: Jim Oliver on January 20, 2017, 07:00:12 AM
Since this is a sport plane w/profile fuselage do yourself a favor and just consider the previously applied dope a filler coat/primer, cover it w/a coat of light grey (polar grey and white combined) then spray your color and clear. The amount of weight you save completely stripping the fuselage isn't worth the effort and smelly mess that bathing it in stripper or lacquer thinner will make...just MHO.  8)


Good advice:)