diff --git a/build/spp.min.js b/build/spp.min.js
index 175f318..19e76df 100644
--- a/build/spp.min.js
+++ b/build/spp.min.js
@@ -15,7 +15,7 @@ this.x)},isPerpTo:function(a){return 0==this.dot(a)},angleBetween:function(a){a=
 SPP.Particle.prototype={constructor:SPP.Particle,init:function(a,b,c){0>=c&&(c=-Infinity);this.position=SPP.VectorPool.get();this.velocity=SPP.VectorPool.get();this.acceleration=SPP.VectorPool.get();this.damp=SPP.VectorPool.get();this.damp.reset(0.1,0.1);this.life=c||Infinity;this.position.reset(a,b)},getForce:function(a){return this._forcesMap[a]},addForce:function(a,b){this._forcesMap[a]=b},removeForce:function(a){this._forcesMap[a].target===this&&(this._forcesMap[a].life=0);delete this._forcesMap[a]},
 removeAllForces:function(){for(var a in this._forcesMap)this.removeForce(a)},render:function(){this.update();this.onUpdate&&this.onUpdate.apply(this);if(null!=this.group){var a=this.group.getForceMap(),b;for(b in a)a[b].render(this)||delete a[b]}for(b in this._forcesMap)this._forcesMap[b].render(this)||this.removeForce(b);this.velocity.add(this.acceleration);this.acceleration.reset(0,0);this.velocity.x*=1-this.damp.x;this.velocity.y*=1-this.damp.y;this.position.add(this.velocity);this.zone&&this.zone.render(this);
 this.life-=SPP.frameTime;0<=this.life||(this.dispatchEvent(new SPP.Event("dead")),this.reset())},update:function(){},dealloc:function(){SPP.VectorPool.recycle(this.position);SPP.VectorPool.recycle(this.velocity);SPP.VectorPool.recycle(this.acceleration);SPP.VectorPool.recycle(this.damp);this.group=this.zone=this.onUpdate=this.extra=this._forcesMap=this.life=this.damp=this.acceleration=this.velocity=this.position=null},reset:function(){SPP.VectorPool.recycle(this.position);SPP.VectorPool.recycle(this.velocity);
-SPP.VectorPool.recycle(this.acceleration);SPP.VectorPool.recycle(this.damp);this.acceleration=this.velocity=this.position=null;this.life=0;this.removeAllForces();this.removeAllEventListeners();for(var a in this.extra)delete this.extra[a];this.group=this.zone=this.onUpdate=null}};SPP.extend(SPP.Particle.prototype,SPP.EventDispatcher.prototype);SPP.Pool=function(){var a=[];this.get=function(b){for(var c in a)if(a[c].constructor===b)return a.splice(c,1)[0];return new b};this.recycle=function(b){a.push(b)};this.getObjects=function(){return a};this.dealloc=function(){for(var b=0,c=a.length;b<c;b++)a[b].dealloc();a.length=0;a=null}};SPP.forcePool=new SPP.Pool;SPP.particlePool=new SPP.Pool;SPP.Group=function(a){var b=a,c={};this.createParticle=function(a){a=b.createParticle(a);a.group=this;return a};this.getForceMap=function(){return c};this.addForce=function(a,b){c[a]=b};this.removeForce=function(a){delete c[a]};this.removeAllForces=function(){for(var a in c)delete c[a]};this.dealloc=function(){this.removeAllForces();c=b=null}};SPP.ParticleSystem=function(){var a=[],b=[],c=[],d=null,g=!1;this.getParticles=function(){return a};this.getForces=function(){return b};this.createParticle=function(b){b=SPP.particlePool.get(b);a.push(b);return b};this.createForce=function(a){a=SPP.forcePool.get(a);b.push(a);return a};this.createGroup=function(){var a=new SPP.Group(this);c.push(a);return a};this.destroyGroup=function(b){var d=c.indexOf(b);if(-1!=d){for(var g=a.length;0<g--;)a[g].parent===b&&(SPP.particlePool.recycle(a[g]),a.splice(g,
+SPP.VectorPool.recycle(this.acceleration);SPP.VectorPool.recycle(this.damp);this.damp=this.acceleration=this.velocity=this.position=null;this.life=0;this.removeAllForces();this.removeAllEventListeners();for(var a in this.extra)delete this.extra[a];this.group=this.zone=this.onUpdate=null}};SPP.extend(SPP.Particle.prototype,SPP.EventDispatcher.prototype);SPP.Pool=function(){var a=[];this.get=function(b){for(var c in a)if(a[c].constructor===b)return a.splice(c,1)[0];return new b};this.recycle=function(b){a.push(b)};this.getObjects=function(){return a};this.dealloc=function(){for(var b=0,c=a.length;b<c;b++)a[b].dealloc();a.length=0;a=null}};SPP.forcePool=new SPP.Pool;SPP.particlePool=new SPP.Pool;SPP.Group=function(a){var b=a,c={};this.createParticle=function(a){a=b.createParticle(a);a.group=this;return a};this.getForceMap=function(){return c};this.addForce=function(a,b){c[a]=b};this.removeForce=function(a){delete c[a]};this.removeAllForces=function(){for(var a in c)delete c[a]};this.dealloc=function(){this.removeAllForces();c=b=null}};SPP.ParticleSystem=function(){var a=[],b=[],c=[],d=null,g=!1;this.getParticles=function(){return a};this.getForces=function(){return b};this.createParticle=function(b){b=SPP.particlePool.get(b);a.push(b);return b};this.createForce=function(a){a=SPP.forcePool.get(a);b.push(a);return a};this.createGroup=function(){var a=new SPP.Group(this);c.push(a);return a};this.destroyGroup=function(b){var d=c.indexOf(b);if(-1!=d){for(var g=a.length;0<g--;)a[g].parent===b&&(SPP.particlePool.recycle(a[g]),a.splice(g,
 1));c.splice(d,1);b.dealloc()}};this.destroyAllGroup=function(){for(var b=a.length;0<b--;)null!=a[b].parent&&(SPP.particlePool.recycle(a[b]),a.splice(b,1));for(var d=0,b=c.length;d<b;d++)c[d].dealloc();c.length=0};this.render=function(){if(g){SPP.frameTime=0.0010*(Date.now()-d);d=Date.now();for(var c=a.length,f=0;f<c;f++)a[f].render();for(;0<c--;)0>=a[c].life&&(SPP.particlePool.recycle(a[c]),a.splice(c,1));for(c=b.length;0<c--;)0>=b[c].life&&(SPP.forcePool.recycle(b[c]),b.splice(c,1))}};this.start=
 function(){d=Date.now();g=!0};this.stop=function(){g=!1};this.destroy=function(){this.stop();g=d=null;for(var e=0,f=a.length;e<f;e++)a[e].dealloc();e=0;for(f=c.length;e<f;e++)c[e].dealloc();e=0;for(f=b.length;e<f;e++)b[e].dealloc();c.length=0;c=null;a.length=0;a=null}};SPP.Zone=function(a,b){this.boundary=a||null;this.type=b||SPP.Zone.OFFSCREEN;this.bounceIntensity=2};SPP.Zone.OFFSCREEN="_offscreen";SPP.Zone.BOUNCE="_bounce";
 SPP.Zone.prototype={constructor:SPP.Zone,render:function(a){this[this.type](a)},_bounce:function(a){if(a.position.x<this.boundary.left()||a.position.x>this.boundary.right())a.position.x=a.position.x<this.boundary.left()?this.boundary.left():this.boundary.right(),a.velocity.scaleX(-this.bounceIntensity);if(a.position.y<this.boundary.top()||a.position.y>this.boundary.bottom())a.position.y=a.position.y<this.boundary.top()?this.boundary.top():this.boundary.bottom(),a.velocity.scaleY(-this.bounceIntensity);
diff --git a/src/particles/Particle.js b/src/particles/Particle.js
index 51aafc4..ba02a6d 100644
--- a/src/particles/Particle.js
+++ b/src/particles/Particle.js
@@ -108,6 +108,7 @@ SPP.Particle.prototype = {
         this.position = null;
         this.velocity = null;
         this.acceleration = null;
+        this.damp = null;
         this.life = 0;
         this.removeAllForces();
         this.removeAllEventListeners();